diff options
| -rw-r--r-- | llvm/test/Transforms/InstCombine/abs-1.ll | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/abs-1.ll b/llvm/test/Transforms/InstCombine/abs-1.ll index 92a9de821aa..ab1fb3f069b 100644 --- a/llvm/test/Transforms/InstCombine/abs-1.ll +++ b/llvm/test/Transforms/InstCombine/abs-1.ll @@ -296,6 +296,61 @@ define i8 @shifty_abs_too_many_uses(i8 %x) { ret i8 %abs } +; There's another way to make abs() using shift, xor, and subtract. +; PR36036 - https://bugs.llvm.org/show_bug.cgi?id=36036 + +define i8 @shifty_sub(i8 %x) { +; CHECK-LABEL: @shifty_sub( +; CHECK-NEXT: [[SH:%.*]] = ashr i8 [[X:%.*]], 7 +; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[SH]], [[X]] +; CHECK-NEXT: [[R:%.*]] = sub i8 [[XOR]], [[SH]] +; CHECK-NEXT: ret i8 [[R]] +; + %sh = ashr i8 %x, 7 + %xor = xor i8 %x, %sh + %r = sub i8 %xor, %sh + ret i8 %r +} + +define i8 @shifty_sub_nsw_commute(i8 %x) { +; CHECK-LABEL: @shifty_sub_nsw_commute( +; CHECK-NEXT: [[SH:%.*]] = ashr i8 [[X:%.*]], 7 +; CHECK-NEXT: [[XOR:%.*]] = xor i8 [[SH]], [[X]] +; CHECK-NEXT: [[R:%.*]] = sub nsw i8 [[XOR]], [[SH]] +; CHECK-NEXT: ret i8 [[R]] +; + %sh = ashr i8 %x, 7 + %xor = xor i8 %sh, %x + %r = sub nsw i8 %xor, %sh + ret i8 %r +} + +define <4 x i32> @shifty_sub_nuw_vec_commute(<4 x i32> %x) { +; CHECK-LABEL: @shifty_sub_nuw_vec_commute( +; CHECK-NEXT: [[SH:%.*]] = ashr <4 x i32> [[X:%.*]], <i32 31, i32 31, i32 31, i32 31> +; CHECK-NEXT: [[XOR:%.*]] = xor <4 x i32> [[SH]], [[X]] +; CHECK-NEXT: [[R:%.*]] = sub nuw <4 x i32> [[XOR]], [[SH]] +; CHECK-NEXT: ret <4 x i32> [[R]] +; + %sh = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31> + %xor = xor <4 x i32> %sh, %x + %r = sub nuw <4 x i32> %xor, %sh + ret <4 x i32> %r +} + +define i12 @shifty_sub_nsw_nuw(i12 %x) { +; CHECK-LABEL: @shifty_sub_nsw_nuw( +; CHECK-NEXT: [[SH:%.*]] = ashr i12 [[X:%.*]], 11 +; CHECK-NEXT: [[XOR:%.*]] = xor i12 [[SH]], [[X]] +; CHECK-NEXT: [[R:%.*]] = sub nuw nsw i12 [[XOR]], [[SH]] +; CHECK-NEXT: ret i12 [[R]] +; + %sh = ashr i12 %x, 11 + %xor = xor i12 %x, %sh + %r = sub nsw nuw i12 %xor, %sh + ret i12 %r +} + define i8 @negate_abs(i8 %x) { ; CHECK-LABEL: @negate_abs( ; CHECK-NEXT: [[N:%.*]] = sub i8 0, [[X:%.*]] @@ -334,3 +389,4 @@ define i1 @abs_must_be_positive(i32 %x) { %c2 = icmp sge i32 %sel, 0 ret i1 %c2 } + |
