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-rw-r--r--llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-a.ll432
-rw-r--r--llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-b.ll407
-rw-r--r--llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-c.ll277
-rw-r--r--llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-d.ll334
-rw-r--r--llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll213
-rw-r--r--llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-f.ll213
-rw-r--r--llvm/test/Transforms/InstCombine/redundant-right-shift-input-masking.ll (renamed from llvm/test/Transforms/InstCombine/redundant-shift-input-masking.ll)0
7 files changed, 1876 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-a.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-a.ll
new file mode 100644
index 00000000000..5c0327695e9
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-a.ll
@@ -0,0 +1,432 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; If we have some pattern that leaves only some low bits set, and then performs
+; left-shift of those bits, if none of the bits that are left after the final
+; shift are modified by the mask, we can omit the mask.
+
+; There are many variants to this pattern:
+; a) (x & ((1 << maskNbits) - 1)) << shiftNbits
+; simplify to:
+; x << shiftNbits
+; iff (maskNbits+shiftNbits) u>= bitwidth(x)
+
+; Simple tests. We don't care about extra uses.
+
+declare void @use32(i32)
+
+define i32 @t0_basic(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t1_bigger_shift(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t1_bigger_shift(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 33, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 33, %nbits ; subtracting from bitwidth+1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t2_bigger_mask(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t2_bigger_mask(
+; CHECK-NEXT: [[T0:%.*]] = add i32 [[NBITS:%.*]], 1
+; CHECK-NEXT: [[T1:%.*]] = shl i32 1, [[T0]]
+; CHECK-NEXT: [[T2:%.*]] = add nsw i32 [[T1]], -1
+; CHECK-NEXT: [[T3:%.*]] = and i32 [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl i32 [[T3]], [[T4]]
+; CHECK-NEXT: ret i32 [[T5]]
+;
+ %t0 = add i32 %nbits, 1
+ %t1 = shl i32 1, %t0 ; shifting by nbits+1
+ %t2 = add nsw i32 %t1, -1
+ %t3 = and i32 %t2, %x
+ %t4 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ %t5 = shl i32 %t3, %t4
+ ret i32 %t5
+}
+
+; Vectors
+
+declare void @use3xi32(<3 x i32>)
+
+define <3 x i32> @t3_vec_splat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_splat(
+; CHECK-NEXT: [[T1:%.*]] = shl <3 x i32> <i32 1, i32 1, i32 1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add nsw <3 x i32> [[T1]], <i32 -1, i32 -1, i32 -1>
+; CHECK-NEXT: [[T3:%.*]] = and <3 x i32> [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub <3 x i32> <i32 32, i32 32, i32 32>, [[NBITS]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[NBITS]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl <3 x i32> [[T3]], [[T4]]
+; CHECK-NEXT: ret <3 x i32> [[T5]]
+;
+ %t0 = add <3 x i32> %nbits, <i32 0, i32 0, i32 0>
+ %t1 = shl <3 x i32> <i32 1, i32 1, i32 1>, %t0
+ %t2 = add nsw <3 x i32> %t1, <i32 -1, i32 -1, i32 -1>
+ %t3 = and <3 x i32> %t2, %x
+ %t4 = sub <3 x i32> <i32 32, i32 32, i32 32>, %nbits
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ call void @use3xi32(<3 x i32> %t4)
+ %t5 = shl <3 x i32> %t3, %t4
+ ret <3 x i32> %t5
+}
+
+define <3 x i32> @t4_vec_nonsplat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t4_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = add <3 x i32> [[NBITS:%.*]], <i32 -1, i32 0, i32 1>
+; CHECK-NEXT: [[T1:%.*]] = shl <3 x i32> <i32 1, i32 1, i32 1>, [[T0]]
+; CHECK-NEXT: [[T2:%.*]] = add nsw <3 x i32> [[T1]], <i32 -1, i32 -1, i32 -1>
+; CHECK-NEXT: [[T3:%.*]] = and <3 x i32> [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub <3 x i32> <i32 33, i32 32, i32 32>, [[NBITS]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl <3 x i32> [[T3]], [[T4]]
+; CHECK-NEXT: ret <3 x i32> [[T5]]
+;
+ %t0 = add <3 x i32> %nbits, <i32 -1, i32 0, i32 1>
+ %t1 = shl <3 x i32> <i32 1, i32 1, i32 1>, %t0
+ %t2 = add nsw <3 x i32> %t1, <i32 -1, i32 -1, i32 -1>
+ %t3 = and <3 x i32> %t2, %x
+ %t4 = sub <3 x i32> <i32 33, i32 32, i32 32>, %nbits
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ call void @use3xi32(<3 x i32> %t4)
+ %t5 = shl <3 x i32> %t3, %t4
+ ret <3 x i32> %t5
+}
+
+define <3 x i32> @t5_vec_undef(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t5_vec_undef(
+; CHECK-NEXT: [[T1:%.*]] = shl <3 x i32> <i32 1, i32 undef, i32 1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add nsw <3 x i32> [[T1]], <i32 -1, i32 undef, i32 -1>
+; CHECK-NEXT: [[T3:%.*]] = and <3 x i32> [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub <3 x i32> <i32 32, i32 undef, i32 32>, [[NBITS]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[NBITS]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl <3 x i32> [[T3]], [[T4]]
+; CHECK-NEXT: ret <3 x i32> [[T5]]
+;
+ %t0 = add <3 x i32> %nbits, <i32 0, i32 undef, i32 0>
+ %t1 = shl <3 x i32> <i32 1, i32 undef, i32 1>, %t0
+ %t2 = add nsw <3 x i32> %t1, <i32 -1, i32 undef, i32 -1>
+ %t3 = and <3 x i32> %t2, %x
+ %t4 = sub <3 x i32> <i32 32, i32 undef, i32 32>, %nbits
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ call void @use3xi32(<3 x i32> %t4)
+ %t5 = shl <3 x i32> %t3, %t4
+ ret <3 x i32> %t5
+}
+
+; Commutativity
+
+declare i32 @gen32()
+
+define i32 @t6_commutativity0(i32 %nbits) {
+; CHECK-LABEL: @t6_commutativity0(
+; CHECK-NEXT: [[X:%.*]] = call i32 @gen32()
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[X]], [[T1]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %x = call i32 @gen32()
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %x, %t1 ; swapped
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t6_commutativity1(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity1(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = shl i32 1, [[NBITS1:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = add nsw i32 [[T2]], -1
+; CHECK-NEXT: [[T4:%.*]] = and i32 [[T3]], [[T1]]
+; CHECK-NEXT: [[T5:%.*]] = sub i32 32, [[NBITS0]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: call void @use32(i32 [[T5]])
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits0
+ %t1 = add nsw i32 %t0, -1
+ %t2 = shl i32 1, %nbits1
+ %t3 = add nsw i32 %t2, -1
+ %t4 = and i32 %t3, %t1 ; both hands of 'and' could be mask..
+ %t5 = sub i32 32, %nbits0
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ call void @use32(i32 %t5)
+ %t6 = shl i32 %t4, %t5
+ ret i32 %t4
+}
+define i32 @t6_commutativity2(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity2(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = shl i32 1, [[NBITS1:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = add nsw i32 [[T2]], -1
+; CHECK-NEXT: [[T4:%.*]] = and i32 [[T3]], [[T1]]
+; CHECK-NEXT: [[T5:%.*]] = sub i32 32, [[NBITS1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: call void @use32(i32 [[T5]])
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits0
+ %t1 = add nsw i32 %t0, -1
+ %t2 = shl i32 1, %nbits1
+ %t3 = add nsw i32 %t2, -1
+ %t4 = and i32 %t3, %t1 ; both hands of 'and' could be mask..
+ %t5 = sub i32 32, %nbits1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ call void @use32(i32 %t5)
+ %t6 = shl i32 %t4, %t5
+ ret i32 %t4
+}
+
+; Fast-math flags. We must not preserve them!
+
+define i32 @t7_nuw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t7_nuw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl nuw i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl nuw i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t8_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t8_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl nsw i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl nsw i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t9_nuw_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t9_nuw_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl nuw nsw i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl nuw nsw i32 %t2, %t3
+ ret i32 %t4
+}
+
+; Negative tests
+
+define i32 @n10(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n10(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 2, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 2, %nbits ; shifting not '-1'
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @n11(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n11(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], 2147483647
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, 2147483647 ; adding not '-1'
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @n12(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n12(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = add nsw i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 31, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 1, %nbits
+ %t1 = add nsw i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 31, %nbits ; summary shift amount is less than 32
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-b.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-b.ll
new file mode 100644
index 00000000000..e0a3aee01ef
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-b.ll
@@ -0,0 +1,407 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; If we have some pattern that leaves only some low bits set, and then performs
+; left-shift of those bits, if none of the bits that are left after the final
+; shift are modified by the mask, we can omit the mask.
+
+; There are many variants to this pattern:
+; b) (x & (~(-1 << maskNbits))) << shiftNbits
+; simplify to:
+; x << shiftNbits
+; iff (maskNbits+shiftNbits) u>= bitwidth(x)
+
+; Simple tests. We don't care about extra uses.
+
+declare void @use32(i32)
+
+define i32 @t0_basic(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t1_bigger_shift(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t1_bigger_shift(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 33, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 33, %nbits ; subtracting from bitwidth+1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t2_bigger_mask(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t2_bigger_mask(
+; CHECK-NEXT: [[T0:%.*]] = add i32 [[NBITS:%.*]], 1
+; CHECK-NEXT: [[T1:%.*]] = shl i32 -1, [[T0]]
+; CHECK-NEXT: [[T2:%.*]] = xor i32 [[T1]], -1
+; CHECK-NEXT: [[T3:%.*]] = and i32 [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl i32 [[T3]], [[T4]]
+; CHECK-NEXT: ret i32 [[T5]]
+;
+ %t0 = add i32 %nbits, 1
+ %t1 = shl i32 -1, %t0 ; shifting by nbits+1
+ %t2 = xor i32 %t1, -1
+ %t3 = and i32 %t2, %x
+ %t4 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ %t5 = shl i32 %t3, %t4
+ ret i32 %t5
+}
+
+; Vectors
+
+declare void @use3xi32(<3 x i32>)
+
+define <3 x i32> @t3_vec_splat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_splat(
+; CHECK-NEXT: [[T1:%.*]] = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = xor <3 x i32> [[T1]], <i32 -1, i32 -1, i32 -1>
+; CHECK-NEXT: [[T3:%.*]] = and <3 x i32> [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub <3 x i32> <i32 32, i32 32, i32 32>, [[NBITS]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[NBITS]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl <3 x i32> [[T3]], [[T4]]
+; CHECK-NEXT: ret <3 x i32> [[T5]]
+;
+ %t0 = add <3 x i32> %nbits, <i32 0, i32 0, i32 0>
+ %t1 = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, %t0
+ %t2 = xor <3 x i32> %t1, <i32 -1, i32 -1, i32 -1>
+ %t3 = and <3 x i32> %t2, %x
+ %t4 = sub <3 x i32> <i32 32, i32 32, i32 32>, %nbits
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ call void @use3xi32(<3 x i32> %t4)
+ %t5 = shl <3 x i32> %t3, %t4
+ ret <3 x i32> %t5
+}
+
+define <3 x i32> @t4_vec_nonsplat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t4_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = add <3 x i32> [[NBITS:%.*]], <i32 -1, i32 0, i32 1>
+; CHECK-NEXT: [[T1:%.*]] = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, [[T0]]
+; CHECK-NEXT: [[T2:%.*]] = xor <3 x i32> [[T1]], <i32 -1, i32 -1, i32 -1>
+; CHECK-NEXT: [[T3:%.*]] = and <3 x i32> [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub <3 x i32> <i32 33, i32 32, i32 32>, [[NBITS]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl <3 x i32> [[T3]], [[T4]]
+; CHECK-NEXT: ret <3 x i32> [[T5]]
+;
+ %t0 = add <3 x i32> %nbits, <i32 -1, i32 0, i32 1>
+ %t1 = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, %t0
+ %t2 = xor <3 x i32> %t1, <i32 -1, i32 -1, i32 -1>
+ %t3 = and <3 x i32> %t2, %x
+ %t4 = sub <3 x i32> <i32 33, i32 32, i32 32>, %nbits
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ call void @use3xi32(<3 x i32> %t4)
+ %t5 = shl <3 x i32> %t3, %t4
+ ret <3 x i32> %t5
+}
+
+define <3 x i32> @t5_vec_undef(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t5_vec_undef(
+; CHECK-NEXT: [[T1:%.*]] = shl <3 x i32> <i32 -1, i32 undef, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = xor <3 x i32> [[T1]], <i32 -1, i32 undef, i32 -1>
+; CHECK-NEXT: [[T3:%.*]] = and <3 x i32> [[T2]], [[X:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = sub <3 x i32> <i32 32, i32 undef, i32 32>, [[NBITS]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[NBITS]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl <3 x i32> [[T3]], [[T4]]
+; CHECK-NEXT: ret <3 x i32> [[T5]]
+;
+ %t0 = add <3 x i32> %nbits, <i32 0, i32 undef, i32 0>
+ %t1 = shl <3 x i32> <i32 -1, i32 undef, i32 -1>, %t0
+ %t2 = xor <3 x i32> %t1, <i32 -1, i32 undef, i32 -1>
+ %t3 = and <3 x i32> %t2, %x
+ %t4 = sub <3 x i32> <i32 32, i32 undef, i32 32>, %nbits
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ call void @use3xi32(<3 x i32> %t4)
+ %t5 = shl <3 x i32> %t3, %t4
+ ret <3 x i32> %t5
+}
+
+; Commutativity
+
+declare i32 @gen32()
+
+define i32 @t6_commutativity0(i32 %nbits) {
+; CHECK-LABEL: @t6_commutativity0(
+; CHECK-NEXT: [[X:%.*]] = call i32 @gen32()
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[X]], [[T1]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %x = call i32 @gen32()
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %x, %t1 ; swapped
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t6_commutativity1(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity1(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = shl i32 -1, [[NBITS1:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = xor i32 [[T2]], -1
+; CHECK-NEXT: [[T4:%.*]] = and i32 [[T3]], [[T1]]
+; CHECK-NEXT: [[T5:%.*]] = sub i32 32, [[NBITS0]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: call void @use32(i32 [[T5]])
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits0
+ %t1 = xor i32 %t0, -1
+ %t2 = shl i32 -1, %nbits1
+ %t3 = xor i32 %t2, -1
+ %t4 = and i32 %t3, %t1 ; both hands of 'and' could be mask..
+ %t5 = sub i32 32, %nbits0
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ call void @use32(i32 %t5)
+ %t6 = shl i32 %t4, %t5
+ ret i32 %t4
+}
+define i32 @t6_commutativity2(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity2(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = shl i32 -1, [[NBITS1:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = xor i32 [[T2]], -1
+; CHECK-NEXT: [[T4:%.*]] = and i32 [[T3]], [[T1]]
+; CHECK-NEXT: [[T5:%.*]] = sub i32 32, [[NBITS1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: call void @use32(i32 [[T5]])
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits0
+ %t1 = xor i32 %t0, -1
+ %t2 = shl i32 -1, %nbits1
+ %t3 = xor i32 %t2, -1
+ %t4 = and i32 %t3, %t1 ; both hands of 'and' could be mask..
+ %t5 = sub i32 32, %nbits1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ call void @use32(i32 %t5)
+ %t6 = shl i32 %t4, %t5
+ ret i32 %t4
+}
+
+; Fast-math flags. We must not preserve them!
+
+define i32 @t7_nuw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t7_nuw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl nuw i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl nuw i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t8_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t8_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl nsw i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl nsw i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @t9_nuw_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t9_nuw_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl nuw nsw i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl nuw nsw i32 %t2, %t3
+ ret i32 %t4
+}
+
+; Negative tests
+
+define i32 @n10(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n10(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -2, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 32, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -2, %nbits ; shifting not '-1'
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 32, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+define i32 @n11(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n11(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i32 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = sub i32 31, [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = xor i32 %t0, -1
+ %t2 = and i32 %t1, %x
+ %t3 = sub i32 31, %nbits ; summary shift amount is less than 32
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-c.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-c.ll
new file mode 100644
index 00000000000..cf47d96ca2b
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-c.ll
@@ -0,0 +1,277 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; If we have some pattern that leaves only some low bits set, and then performs
+; left-shift of those bits, if none of the bits that are left after the final
+; shift are modified by the mask, we can omit the mask.
+
+; There are many variants to this pattern:
+; c) (x & (-1 >> maskNbits)) << shiftNbits
+; simplify to:
+; x << shiftNbits
+; iff (shiftNbits-maskNbits) s>= 0 (i.e. shiftNbits u>= maskNbits)
+
+; Simple tests. We don't care about extra uses.
+
+declare void @use32(i32)
+
+define i32 @t0_basic(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %t0, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t1_bigger_shift(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t1_bigger_shift(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add i32 [[NBITS]], 1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T1]], [[T2]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %t0, %x
+ %t2 = add i32 %nbits, 1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t1, %t2
+ ret i32 %t3
+}
+
+; Vectors
+
+declare void @use3xi32(<3 x i32>)
+
+define <3 x i32> @t2_vec_splat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t2_vec_splat(
+; CHECK-NEXT: [[T0:%.*]] = lshr <3 x i32> <i32 -1, i32 -1, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and <3 x i32> [[T0]], [[X:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 1, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = lshr <3 x i32> <i32 -1, i32 -1, i32 -1>, %nbits
+ %t1 = and <3 x i32> %t0, %x
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 1, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+define <3 x i32> @t3_vec_nonsplat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = lshr <3 x i32> <i32 -1, i32 -1, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and <3 x i32> [[T0]], [[X:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 0, i32 2>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = lshr <3 x i32> <i32 -1, i32 -1, i32 -1>, %nbits
+ %t1 = and <3 x i32> %t0, %x
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 0, i32 2>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+define <3 x i32> @t4_vec_undef(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t4_vec_undef(
+; CHECK-NEXT: [[T0:%.*]] = lshr <3 x i32> <i32 -1, i32 undef, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and <3 x i32> [[T0]], [[X:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 undef, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = lshr <3 x i32> <i32 -1, i32 undef, i32 -1>, %nbits
+ %t1 = and <3 x i32> %t0, %x
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 undef, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+; Commutativity
+
+declare i32 @gen32()
+
+define i32 @t5_commutativity0(i32 %nbits) {
+; CHECK-LABEL: @t5_commutativity0(
+; CHECK-NEXT: [[X:%.*]] = call i32 @gen32()
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[X]], [[T0]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %x = call i32 @gen32()
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %x, %t0 ; swapped
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t6_commutativity1(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity1(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 -1, [[NBITS1:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T0]], [[T1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T2]], [[NBITS0]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = lshr i32 -1, %nbits0
+ %t1 = lshr i32 -1, %nbits1
+ %t2 = and i32 %t0, %t1 ; both hands of 'and' could be mask..
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t2, %nbits0
+ ret i32 %t3
+}
+define i32 @t7_commutativity2(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t7_commutativity2(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 -1, [[NBITS1:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T0]], [[T1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T2]], [[NBITS1]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = lshr i32 -1, %nbits0
+ %t1 = lshr i32 -1, %nbits1
+ %t2 = and i32 %t0, %t1 ; both hands of 'and' could be mask..
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t2, %nbits1
+ ret i32 %t3
+}
+
+; Fast-math flags. We must not preserve them!
+
+define i32 @t8_nuw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t8_nuw(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nuw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %t0, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nuw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t9_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t9_nsw(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %t0, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nsw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t10_nuw_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t10_nuw_nsw(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nuw nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %t0, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nuw nsw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+; Negative tests
+
+define i32 @n11(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n11(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -2, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = lshr i32 -2, %nbits ; shifting not '-1'
+ %t1 = and i32 %t0, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @n12(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n12(
+; CHECK-NEXT: [[T0:%.*]] = lshr i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = and i32 [[T0]], [[X:%.*]]
+; CHECK-NEXT: [[T2:%.*]] = add i32 [[NBITS]], -1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = lshr i32 -1, %nbits
+ %t1 = and i32 %t0, %x
+ %t2 = add i32 %nbits, -1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t1, %t2 ; shift is smaller than mask
+ ret i32 %t2
+}
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-d.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-d.ll
new file mode 100644
index 00000000000..4505f32dd01
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-d.ll
@@ -0,0 +1,334 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; If we have some pattern that leaves only some low bits set, and then performs
+; left-shift of those bits, if none of the bits that are left after the final
+; shift are modified by the mask, we can omit the mask.
+
+; There are many variants to this pattern:
+; d) (x & ((-1 << maskNbits) >> maskNbits)) << shiftNbits
+; simplify to:
+; x << shiftNbits
+; iff (shiftNbits-maskNbits) s>= 0 (i.e. shiftNbits u>= maskNbits)
+
+; Simple tests. We don't care about extra uses.
+
+declare void @use32(i32)
+
+define i32 @t0_basic(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t4 = shl i32 %t2, %nbits
+ ret i32 %t4
+}
+
+define i32 @t1_bigger_shift(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t1_bigger_shift(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = add i32 [[NBITS]], 1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[T3]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ %t3 = add i32 %nbits, 1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ %t4 = shl i32 %t2, %t3
+ ret i32 %t4
+}
+
+; Vectors
+
+declare void @use3xi32(<3 x i32>)
+
+define <3 x i32> @t3_vec_splat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_splat(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and <3 x i32> [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 1, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl <3 x i32> [[T2]], [[T3]]
+; CHECK-NEXT: ret <3 x i32> [[T4]]
+;
+ %t0 = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, %nbits
+ %t1 = lshr <3 x i32> %t0, %nbits
+ %t2 = and <3 x i32> %t1, %x
+ %t3 = add <3 x i32> %nbits, <i32 1, i32 1, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ %t4 = shl <3 x i32> %t2, %t3
+ ret <3 x i32> %t4
+}
+
+define <3 x i32> @t4_vec_nonsplat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t4_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and <3 x i32> [[T1]], [[X:%.*]]
+; CHECK-NEXT: [[T3:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 0, i32 2>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T3]])
+; CHECK-NEXT: [[T4:%.*]] = shl <3 x i32> [[T2]], [[T3]]
+; CHECK-NEXT: ret <3 x i32> [[T4]]
+;
+ %t0 = shl <3 x i32> <i32 -1, i32 -1, i32 -1>, %nbits
+ %t1 = lshr <3 x i32> %t0, %nbits
+ %t2 = and <3 x i32> %t1, %x
+ %t3 = add <3 x i32> %nbits, <i32 1, i32 0, i32 2>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ %t4 = shl <3 x i32> %t2, %t3
+ ret <3 x i32> %t4
+}
+
+define <3 x i32> @t5_vec_undef(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t5_vec_undef(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> <i32 -1, i32 undef, i32 -1>, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and <3 x i32> [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[NBITS]])
+; CHECK-NEXT: [[T4:%.*]] = shl <3 x i32> [[T2]], [[NBITS]]
+; CHECK-NEXT: ret <3 x i32> [[T4]]
+;
+ %t0 = shl <3 x i32> <i32 -1, i32 undef, i32 -1>, %nbits
+ %t1 = lshr <3 x i32> %t0, %nbits
+ %t2 = and <3 x i32> %t1, %x
+ %t3 = add <3 x i32> %nbits, <i32 0, i32 undef, i32 0>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ call void @use3xi32(<3 x i32> %t3)
+ %t4 = shl <3 x i32> %t2, %t3
+ ret <3 x i32> %t4
+}
+
+; Commutativity
+
+declare i32 @gen32()
+
+define i32 @t6_commutativity0(i32 %nbits) {
+; CHECK-LABEL: @t6_commutativity0(
+; CHECK-NEXT: [[X:%.*]] = call i32 @gen32()
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[X]], [[T1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %x = call i32 @gen32()
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %x, %t1 ; swapped order
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t2, %nbits
+ ret i32 %t3
+}
+
+define i32 @t6_commutativity1(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity1(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS0]]
+; CHECK-NEXT: [[T2:%.*]] = shl i32 -1, [[NBITS0]]
+; CHECK-NEXT: [[T3:%.*]] = lshr i32 [[T0]], [[NBITS1:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = and i32 [[T3]], [[T1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl i32 [[T4]], [[NBITS0]]
+; CHECK-NEXT: ret i32 [[T5]]
+;
+ %t0 = shl i32 -1, %nbits0
+ %t1 = lshr i32 %t0, %nbits0
+ %t2 = shl i32 -1, %nbits0
+ %t3 = lshr i32 %t0, %nbits1
+ %t4 = and i32 %t3, %t1 ; both hands of 'and' could be mask..
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ %t5 = shl i32 %t4, %nbits0
+ ret i32 %t5
+}
+define i32 @t6_commutativity2(i32 %nbits0, i32 %nbits1) {
+; CHECK-LABEL: @t6_commutativity2(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS0]]
+; CHECK-NEXT: [[T2:%.*]] = shl i32 -1, [[NBITS0]]
+; CHECK-NEXT: [[T3:%.*]] = lshr i32 [[T0]], [[NBITS1:%.*]]
+; CHECK-NEXT: [[T4:%.*]] = and i32 [[T3]], [[T1]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: call void @use32(i32 [[T3]])
+; CHECK-NEXT: call void @use32(i32 [[T4]])
+; CHECK-NEXT: [[T5:%.*]] = shl i32 [[T4]], [[NBITS1]]
+; CHECK-NEXT: ret i32 [[T5]]
+;
+ %t0 = shl i32 -1, %nbits0
+ %t1 = lshr i32 %t0, %nbits0
+ %t2 = shl i32 -1, %nbits0
+ %t3 = lshr i32 %t0, %nbits1
+ %t4 = and i32 %t3, %t1 ; both hands of 'and' could be mask..
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ call void @use32(i32 %t3)
+ call void @use32(i32 %t4)
+ %t5 = shl i32 %t4, %nbits1
+ ret i32 %t5
+}
+
+; Fast-math flags. We must not preserve them!
+
+define i32 @t7_nuw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t7_nuw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl nuw i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl nuw i32 %t2, %nbits
+ ret i32 %t3
+}
+
+define i32 @t8_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t8_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl nsw i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl nsw i32 %t2, %nbits
+ ret i32 %t3
+}
+
+define i32 @t9_nuw_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t9_nuw_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl nuw nsw i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl nuw nsw i32 %t2, %nbits
+ ret i32 %t3
+}
+
+; Negative tests
+
+define i32 @n10(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n10(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -2, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = shl i32 -2, %nbits ; shifting not '-1'
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t2, %nbits
+ ret i32 %t3
+}
+
+define i32 @n11(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n11(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -1, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = and i32 [[T1]], [[X:%.*]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T4:%.*]] = shl i32 [[T2]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T4]]
+;
+ %t0 = shl i32 -1, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = and i32 %t1, %x
+ %t3 = add i32 %nbits, -1 ; shift is smaller than mask
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t4 = shl i32 %t2, %nbits
+ ret i32 %t4
+}
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll
new file mode 100644
index 00000000000..a90aa29b9fc
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll
@@ -0,0 +1,213 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; If we have some pattern that leaves only some low bits set, and then performs
+; left-shift of those bits, if none of the bits that are left after the final
+; shift are modified by the mask, we can omit the mask.
+
+; There are many variants to this pattern:
+; e) ((x << maskNbits) l>> maskNbits) << shiftNbits
+; simplify to:
+; x << shiftNbits
+; iff (shiftNbits-maskNbits) s>= 0 (i.e. shiftNbits u>= maskNbits)
+
+; Simple tests. We don't care about extra uses.
+
+declare void @use32(i32)
+
+define i32 @t0_basic(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t1_bigger_shift(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t1_bigger_shift(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add i32 [[NBITS]], 1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T1]], [[T2]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = add i32 %nbits, 1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t1, %t2
+ ret i32 %t3
+}
+
+; Vectors
+
+declare void @use3xi32(<3 x i32>)
+
+define <3 x i32> @t2_vec_splat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t2_vec_splat(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 1, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = shl <3 x i32> %x, %nbits
+ %t1 = lshr <3 x i32> %t0, %nbits
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 1, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+define <3 x i32> @t3_vec_nonsplat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 0, i32 2>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = shl <3 x i32> %x, %nbits
+ %t1 = lshr <3 x i32> %t0, %nbits
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 0, i32 2>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+define <3 x i32> @t4_vec_undef(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t4_vec_undef(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 undef, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = shl <3 x i32> %x, %nbits
+ %t1 = lshr <3 x i32> %t0, %nbits
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 undef, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+; Fast-math flags. We must not preserve them!
+
+define i32 @t8_nuw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t8_nuw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nuw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nuw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t9_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t9_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nsw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t10_nuw_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t10_nuw_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nuw nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nuw nsw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+; Negative tests
+
+define i32 @n11(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n11(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -2, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 -2, %nbits ; shifting not '-1'
+ %t1 = lshr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @n12(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n12(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add i32 [[NBITS]], -1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = lshr i32 %t0, %nbits
+ %t2 = add i32 %nbits, -1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t1, %t2 ; shift is smaller than mask
+ ret i32 %t2
+}
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-f.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-f.ll
new file mode 100644
index 00000000000..4414c0e7c2c
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-f.ll
@@ -0,0 +1,213 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; If we have some pattern that leaves only some low bits set, and then performs
+; left-shift of those bits, if none of the bits that are left after the final
+; shift are modified by the mask, we can omit the mask.
+
+; There are many variants to this pattern:
+; f) ((x << maskNbits) a>> maskNbits) << shiftNbits
+; simplify to:
+; x << shiftNbits
+; iff (shiftNbits-maskNbits) s>= 0 (i.e. shiftNbits u>= maskNbits)
+
+; Simple tests. We don't care about extra uses.
+
+declare void @use32(i32)
+
+define i32 @t0_basic(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = ashr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t1_bigger_shift(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t1_bigger_shift(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add i32 [[NBITS]], 1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl i32 [[T1]], [[T2]]
+; CHECK-NEXT: ret i32 [[T3]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = ashr i32 %t0, %nbits
+ %t2 = add i32 %nbits, 1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t1, %t2
+ ret i32 %t3
+}
+
+; Vectors
+
+declare void @use3xi32(<3 x i32>)
+
+define <3 x i32> @t2_vec_splat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t2_vec_splat(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 1, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = shl <3 x i32> %x, %nbits
+ %t1 = ashr <3 x i32> %t0, %nbits
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 1, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+define <3 x i32> @t3_vec_nonsplat(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 0, i32 2>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = shl <3 x i32> %x, %nbits
+ %t1 = ashr <3 x i32> %t0, %nbits
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 0, i32 2>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+define <3 x i32> @t4_vec_undef(<3 x i32> %x, <3 x i32> %nbits) {
+; CHECK-LABEL: @t4_vec_undef(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i32> [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr <3 x i32> [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add <3 x i32> [[NBITS]], <i32 1, i32 undef, i32 1>
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T0]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T1]])
+; CHECK-NEXT: call void @use3xi32(<3 x i32> [[T2]])
+; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT: ret <3 x i32> [[T3]]
+;
+ %t0 = shl <3 x i32> %x, %nbits
+ %t1 = ashr <3 x i32> %t0, %nbits
+ %t2 = add <3 x i32> %nbits, <i32 1, i32 undef, i32 1>
+ call void @use3xi32(<3 x i32> %t0)
+ call void @use3xi32(<3 x i32> %t1)
+ call void @use3xi32(<3 x i32> %t2)
+ %t3 = shl <3 x i32> %t1, %t2
+ ret <3 x i32> %t3
+}
+
+; Fast-math flags. We must not preserve them!
+
+define i32 @t8_nuw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t8_nuw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nuw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = ashr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nuw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t9_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t9_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = ashr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nsw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @t10_nuw_nsw(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @t10_nuw_nsw(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl nuw nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = ashr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl nuw nsw i32 %t1, %nbits
+ ret i32 %t2
+}
+
+; Negative tests
+
+define i32 @n11(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n11(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 -2, [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 -2, %nbits ; shifting not '-1'
+ %t1 = ashr i32 %t0, %nbits
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ %t2 = shl i32 %t1, %nbits
+ ret i32 %t2
+}
+
+define i32 @n12(i32 %x, i32 %nbits) {
+; CHECK-LABEL: @n12(
+; CHECK-NEXT: [[T0:%.*]] = shl i32 [[X:%.*]], [[NBITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = ashr i32 [[T0]], [[NBITS]]
+; CHECK-NEXT: [[T2:%.*]] = add i32 [[NBITS]], -1
+; CHECK-NEXT: call void @use32(i32 [[T0]])
+; CHECK-NEXT: call void @use32(i32 [[T1]])
+; CHECK-NEXT: call void @use32(i32 [[T2]])
+; CHECK-NEXT: ret i32 [[T2]]
+;
+ %t0 = shl i32 %x, %nbits
+ %t1 = ashr i32 %t0, %nbits
+ %t2 = add i32 %nbits, -1
+ call void @use32(i32 %t0)
+ call void @use32(i32 %t1)
+ call void @use32(i32 %t2)
+ %t3 = shl i32 %t1, %t2 ; shift is smaller than mask
+ ret i32 %t2
+}
diff --git a/llvm/test/Transforms/InstCombine/redundant-shift-input-masking.ll b/llvm/test/Transforms/InstCombine/redundant-right-shift-input-masking.ll
index 03920267525..03920267525 100644
--- a/llvm/test/Transforms/InstCombine/redundant-shift-input-masking.ll
+++ b/llvm/test/Transforms/InstCombine/redundant-right-shift-input-masking.ll
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