1 files changed, 169 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-after-truncation-variant-c.ll b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-after-truncation-variant-c.ll
new file mode 100644
index 00000000000..67849aa2f56
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/redundant-left-shift-input-masking-after-truncation-variant-c.ll
@@ -0,0 +1,169 @@
+; 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, we can combine those two shifts into a shift+mask.
+
+; There are many variants to this pattern:
+;   c)  (trunc ((x & (-1 >> maskNbits)))) << shiftNbits
+; simplify to:
+;   (trunc(x)) << shiftNbits
+
+; Simple tests.
+
+declare void @use32(i32)
+declare void @use64(i64)
+
+define i32 @t0_basic(i64 %x, i32 %nbits) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT:    [[T0:%.*]] = zext i32 [[NBITS:%.*]] to i64
+; CHECK-NEXT:    [[T1:%.*]] = lshr i64 -1, [[T0]]
+; CHECK-NEXT:    [[T2:%.*]] = add i32 [[NBITS]], -32
+; CHECK-NEXT:    [[T3:%.*]] = and i64 [[T1]], [[X:%.*]]
+; CHECK-NEXT:    call void @use64(i64 [[T0]])
+; CHECK-NEXT:    call void @use64(i64 [[T1]])
+; CHECK-NEXT:    call void @use32(i32 [[T2]])
+; CHECK-NEXT:    call void @use64(i64 [[T3]])
+; CHECK-NEXT:    [[T4:%.*]] = trunc i64 [[T3]] to i32
+; CHECK-NEXT:    [[T5:%.*]] = shl i32 [[T4]], [[T2]]
+; CHECK-NEXT:    ret i32 [[T5]]
+;
+  %t0 = zext i32 %nbits to i64
+  %t1 = lshr i64 -1, %t0
+  %t2 = add i32 %nbits, -32
+  %t3 = and i64 %t1, %x
+
+  call void @use64(i64 %t0)
+  call void @use64(i64 %t1)
+  call void @use32(i32 %t2)
+  call void @use64(i64 %t3)
+
+  %t4 = trunc i64 %t3 to i32
+  %t5 = shl i32 %t4, %t2
+  ret i32 %t5
+}
+
+; Vectors
+
+declare void @use8xi32(<8 x i32>)
+declare void @use8xi64(<8 x i64>)
+
+define <8 x i32> @t1_vec_splat(<8 x i64> %x, <8 x i32> %nbits) {
+; CHECK-LABEL: @t1_vec_splat(
+; CHECK-NEXT:    [[T0:%.*]] = zext <8 x i32> [[NBITS:%.*]] to <8 x i64>
+; CHECK-NEXT:    [[T1:%.*]] = lshr <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1>, [[T0]]
+; CHECK-NEXT:    [[T2:%.*]] = add <8 x i32> [[NBITS]], <i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32>
+; CHECK-NEXT:    [[T3:%.*]] = and <8 x i64> [[T1]], [[X:%.*]]
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T0]])
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T1]])
+; CHECK-NEXT:    call void @use8xi32(<8 x i32> [[T2]])
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T3]])
+; CHECK-NEXT:    [[T4:%.*]] = trunc <8 x i64> [[T3]] to <8 x i32>
+; CHECK-NEXT:    [[T5:%.*]] = shl <8 x i32> [[T4]], [[T2]]
+; CHECK-NEXT:    ret <8 x i32> [[T5]]
+;
+  %t0 = zext <8 x i32> %nbits to <8 x i64>
+  %t1 = lshr <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1>, %t0
+  %t2 = add <8 x i32> %nbits, <i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32>
+  %t3 = and <8 x i64> %t1, %x
+
+  call void @use8xi64(<8 x i64> %t0)
+  call void @use8xi64(<8 x i64> %t1)
+  call void @use8xi32(<8 x i32> %t2)
+  call void @use8xi64(<8 x i64> %t3)
+
+  %t4 = trunc <8 x i64> %t3 to <8 x i32>
+  %t5 = shl <8 x i32> %t4, %t2
+  ret <8 x i32> %t5
+}
+
+define <8 x i32> @t2_vec_splat_undef(<8 x i64> %x, <8 x i32> %nbits) {
+; CHECK-LABEL: @t2_vec_splat_undef(
+; CHECK-NEXT:    [[T0:%.*]] = zext <8 x i32> [[NBITS:%.*]] to <8 x i64>
+; CHECK-NEXT:    [[T1:%.*]] = lshr <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 undef, i64 -1>, [[T0]]
+; CHECK-NEXT:    [[T2:%.*]] = add <8 x i32> [[NBITS]], <i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 undef, i32 -32>
+; CHECK-NEXT:    [[T3:%.*]] = and <8 x i64> [[T1]], [[X:%.*]]
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T0]])
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T1]])
+; CHECK-NEXT:    call void @use8xi32(<8 x i32> [[T2]])
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T3]])
+; CHECK-NEXT:    [[T4:%.*]] = trunc <8 x i64> [[T3]] to <8 x i32>
+; CHECK-NEXT:    [[T5:%.*]] = shl <8 x i32> [[T4]], [[T2]]
+; CHECK-NEXT:    ret <8 x i32> [[T5]]
+;
+  %t0 = zext <8 x i32> %nbits to <8 x i64>
+  %t1 = lshr <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 undef, i64 -1>, %t0
+  %t2 = add <8 x i32> %nbits, <i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 -32, i32 undef, i32 -32>
+  %t3 = and <8 x i64> %t1, %x
+
+  call void @use8xi64(<8 x i64> %t0)
+  call void @use8xi64(<8 x i64> %t1)
+  call void @use8xi32(<8 x i32> %t2)
+  call void @use8xi64(<8 x i64> %t3)
+
+  %t4 = trunc <8 x i64> %t3 to <8 x i32>
+  %t5 = shl <8 x i32> %t4, %t2
+  ret <8 x i32> %t5
+}
+
+define <8 x i32> @t3_vec_nonsplat(<8 x i64> %x, <8 x i32> %nbits) {
+; CHECK-LABEL: @t3_vec_nonsplat(
+; CHECK-NEXT:    [[T0:%.*]] = zext <8 x i32> [[NBITS:%.*]] to <8 x i64>
+; CHECK-NEXT:    [[T1:%.*]] = lshr <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 undef, i64 -1>, [[T0]]
+; CHECK-NEXT:    [[T2:%.*]] = add <8 x i32> [[NBITS]], <i32 -32, i32 -1, i32 0, i32 1, i32 31, i32 32, i32 undef, i32 64>
+; CHECK-NEXT:    [[T3:%.*]] = and <8 x i64> [[T1]], [[X:%.*]]
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T0]])
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T1]])
+; CHECK-NEXT:    call void @use8xi32(<8 x i32> [[T2]])
+; CHECK-NEXT:    call void @use8xi64(<8 x i64> [[T3]])
+; CHECK-NEXT:    [[T4:%.*]] = trunc <8 x i64> [[T3]] to <8 x i32>
+; CHECK-NEXT:    [[T5:%.*]] = shl <8 x i32> [[T4]], [[T2]]
+; CHECK-NEXT:    ret <8 x i32> [[T5]]
+;
+  %t0 = zext <8 x i32> %nbits to <8 x i64>
+  %t1 = lshr <8 x i64> <i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 -1, i64 undef, i64 -1>, %t0
+  %t2 = add <8 x i32> %nbits, <i32 -32, i32 -1, i32 0, i32 1, i32 31, i32 32, i32 undef, i32 64>
+  %t3 = and <8 x i64> %t1, %x
+
+  call void @use8xi64(<8 x i64> %t0)
+  call void @use8xi64(<8 x i64> %t1)
+  call void @use8xi32(<8 x i32> %t2)
+  call void @use8xi64(<8 x i64> %t3)
+
+  %t4 = trunc <8 x i64> %t3 to <8 x i32>
+  %t5 = shl <8 x i32> %t4, %t2
+  ret <8 x i32> %t5
+}
+
+; Extra uses.
+
+define i32 @n4_extrause(i64 %x, i32 %nbits) {
+; CHECK-LABEL: @n4_extrause(
+; CHECK-NEXT:    [[T0:%.*]] = zext i32 [[NBITS:%.*]] to i64
+; CHECK-NEXT:    [[T1:%.*]] = lshr i64 -1, [[T0]]
+; CHECK-NEXT:    [[T2:%.*]] = add i32 [[NBITS]], -32
+; CHECK-NEXT:    [[T3:%.*]] = and i64 [[T1]], [[X:%.*]]
+; CHECK-NEXT:    call void @use64(i64 [[T0]])
+; CHECK-NEXT:    call void @use64(i64 [[T1]])
+; CHECK-NEXT:    call void @use32(i32 [[T2]])
+; CHECK-NEXT:    call void @use64(i64 [[T3]])
+; CHECK-NEXT:    [[T4:%.*]] = trunc i64 [[T3]] to i32
+; CHECK-NEXT:    call void @use32(i32 [[T4]])
+; CHECK-NEXT:    [[T5:%.*]] = shl i32 [[T4]], [[T2]]
+; CHECK-NEXT:    ret i32 [[T5]]
+;
+  %t0 = zext i32 %nbits to i64
+  %t1 = lshr i64 -1, %t0
+  %t2 = add i32 %nbits, -32
+  %t3 = and i64 %t1, %x
+
+  call void @use64(i64 %t0)
+  call void @use64(i64 %t1)
+  call void @use32(i32 %t2)
+  call void @use64(i64 %t3)
+
+  %t4 = trunc i64 %t3 to i32
+  call void @use32(i32 %t4)
+  %t5 = shl i32 %t4, %t2
+  ret i32 %t5
+}