[InstCombine] move folds for shift-shift pairs; NFCI

Although this is 'no-functional-change-intended', I'm adding tests
for shl-shl and lshr-lshr pairs because there is no existing test 
coverage for those folds.

It seems like we should be able to remove some code from foldShiftedShift()
at this point because we're handling those patterns on the general path.

llvm-svn: 293814

1 files changed, 52 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/apint-shift.ll b/llvm/test/Transforms/InstCombine/apint-shift.ll
index fc1934b576f..f1276beec9f 100644
--- a/llvm/test/Transforms/InstCombine/apint-shift.ll
+++ b/llvm/test/Transforms/InstCombine/apint-shift.ll
@@ -126,6 +126,32 @@ define <2 x i19> @lshr_lshr_splat_vec(<2 x i19> %X) {
   ret <2 x i19> %sh2
 }
 
+define i9 @multituse_lshr_lshr(i9 %x) {
+; CHECK-LABEL: @multituse_lshr_lshr(
+; CHECK-NEXT:    [[SH1:%.*]] = lshr i9 %x, 2
+; CHECK-NEXT:    [[SH2:%.*]] = lshr i9 %x, 5
+; CHECK-NEXT:    [[MUL:%.*]] = mul i9 [[SH1]], [[SH2]]
+; CHECK-NEXT:    ret i9 [[MUL]]
+;
+  %sh1 = lshr i9 %x, 2
+  %sh2 = lshr i9 %sh1, 3
+  %mul = mul i9 %sh1, %sh2
+  ret i9 %mul
+}
+
+define <2 x i9> @multiuse_lshr_lshr_splat(<2 x i9> %x) {
+; CHECK-LABEL: @multiuse_lshr_lshr_splat(
+; CHECK-NEXT:    [[SH1:%.*]] = lshr <2 x i9> %x, <i9 2, i9 2>
+; CHECK-NEXT:    [[SH2:%.*]] = lshr <2 x i9> %x, <i9 5, i9 5>
+; CHECK-NEXT:    [[MUL:%.*]] = mul <2 x i9> [[SH1]], [[SH2]]
+; CHECK-NEXT:    ret <2 x i9> [[MUL]]
+;
+  %sh1 = lshr <2 x i9> %x, <i9 2, i9 2>
+  %sh2 = lshr <2 x i9> %sh1, <i9 3, i9 3>
+  %mul = mul <2 x i9> %sh1, %sh2
+  ret <2 x i9> %mul
+}
+
 ; Two left shifts in the same direction:
 ; shl (shl X, C1), C2 -->  shl X, C1 + C2
 
@@ -139,6 +165,32 @@ define <2 x i19> @shl_shl_splat_vec(<2 x i19> %X) {
   ret <2 x i19> %sh2
 }
 
+define i42 @multiuse_shl_shl(i42 %x) {
+; CHECK-LABEL: @multiuse_shl_shl(
+; CHECK-NEXT:    [[SH1:%.*]] = shl i42 %x, 8
+; CHECK-NEXT:    [[SH2:%.*]] = shl i42 %x, 17
+; CHECK-NEXT:    [[MUL:%.*]] = mul i42 [[SH1]], [[SH2]]
+; CHECK-NEXT:    ret i42 [[MUL]]
+;
+  %sh1 = shl i42 %x, 8
+  %sh2 = shl i42 %sh1, 9
+  %mul = mul i42 %sh1, %sh2
+  ret i42 %mul
+}
+
+define <2 x i42> @mulituse_shl_shl_splat(<2 x i42> %x) {
+; CHECK-LABEL: @mulituse_shl_shl_splat(
+; CHECK-NEXT:    [[SH1:%.*]] = shl <2 x i42> %x, <i42 8, i42 8>
+; CHECK-NEXT:    [[SH2:%.*]] = shl <2 x i42> %x, <i42 17, i42 17>
+; CHECK-NEXT:    [[MUL:%.*]] = mul <2 x i42> [[SH1]], [[SH2]]
+; CHECK-NEXT:    ret <2 x i42> [[MUL]]
+;
+  %sh1 = shl <2 x i42> %x, <i42 8, i42 8>
+  %sh2 = shl <2 x i42> %sh1, <i42 9, i42 9>
+  %mul = mul <2 x i42> %sh1, %sh2
+  ret <2 x i42> %mul
+}
+
 ; Equal shift amounts in opposite directions become bitwise 'and':
 ; lshr (shl X, C), C --> and X, C'