diff options
Diffstat (limited to 'llvm/test/Transforms/InstSimplify/result-of-usub-by-nonzero-is-non-zero-and-no-overflow.ll')
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/result-of-usub-by-nonzero-is-non-zero-and-no-overflow.ll | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstSimplify/result-of-usub-by-nonzero-is-non-zero-and-no-overflow.ll b/llvm/test/Transforms/InstSimplify/result-of-usub-by-nonzero-is-non-zero-and-no-overflow.ll new file mode 100644 index 00000000000..5a64daf11a4 --- /dev/null +++ b/llvm/test/Transforms/InstSimplify/result-of-usub-by-nonzero-is-non-zero-and-no-overflow.ll @@ -0,0 +1,84 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt %s -instsimplify -S | FileCheck %s + +; Here we subtract two values, check that subtraction did not overflow AND +; that the result is non-zero. This can be simplified just to a comparison +; between the base and offset. + +declare void @llvm.assume(i1) + +define i1 @t0(i8 %base, i8 %offset) { +; CHECK-LABEL: @t0( +; CHECK-NEXT: [[CMP:%.*]] = icmp ne i8 [[OFFSET:%.*]], 0 +; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]]) +; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET]] +; CHECK-NEXT: [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[ADJUSTED]], [[BASE]] +; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0 +; CHECK-NEXT: [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]] +; CHECK-NEXT: ret i1 [[R]] +; + %cmp = icmp ne i8 %offset, 0 + call void @llvm.assume(i1 %cmp) + + %adjusted = sub i8 %base, %offset + %no_underflow = icmp uge i8 %adjusted, %base + %not_null = icmp ne i8 %adjusted, 0 + %r = and i1 %not_null, %no_underflow + ret i1 %r +} + +define i1 @t1(i8 %base, i8 %offset) { +; CHECK-LABEL: @t1( +; CHECK-NEXT: [[CMP:%.*]] = icmp ne i8 [[OFFSET:%.*]], 0 +; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]]) +; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET]] +; CHECK-NEXT: [[NO_UNDERFLOW:%.*]] = icmp ult i8 [[ADJUSTED]], [[BASE]] +; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0 +; CHECK-NEXT: [[R:%.*]] = or i1 [[NOT_NULL]], [[NO_UNDERFLOW]] +; CHECK-NEXT: ret i1 [[R]] +; + %cmp = icmp ne i8 %offset, 0 + call void @llvm.assume(i1 %cmp) + + %adjusted = sub i8 %base, %offset + %no_underflow = icmp ult i8 %adjusted, %base + %not_null = icmp eq i8 %adjusted, 0 + %r = or i1 %not_null, %no_underflow + ret i1 %r +} + +define i1 @t2_commutative(i8 %base, i8 %offset) { +; CHECK-LABEL: @t2_commutative( +; CHECK-NEXT: [[CMP:%.*]] = icmp ne i8 [[OFFSET:%.*]], 0 +; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]]) +; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET]] +; CHECK-NEXT: [[NO_UNDERFLOW:%.*]] = icmp ule i8 [[BASE]], [[ADJUSTED]] +; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0 +; CHECK-NEXT: [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]] +; CHECK-NEXT: ret i1 [[R]] +; + %cmp = icmp ne i8 %offset, 0 + call void @llvm.assume(i1 %cmp) + + %adjusted = sub i8 %base, %offset + %no_underflow = icmp ule i8 %base, %adjusted + %not_null = icmp ne i8 %adjusted, 0 + %r = and i1 %not_null, %no_underflow + ret i1 %r +} + +; We don't know that offset is non-zero, so we can't fold. +define i1 @t3_bad(i8 %base, i8 %offset) { +; CHECK-LABEL: @t3_bad( +; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]] +; CHECK-NEXT: [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[ADJUSTED]], [[BASE]] +; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0 +; CHECK-NEXT: [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]] +; CHECK-NEXT: ret i1 [[R]] +; + %adjusted = sub i8 %base, %offset + %no_underflow = icmp uge i8 %adjusted, %base + %not_null = icmp ne i8 %adjusted, 0 + %r = and i1 %not_null, %no_underflow + ret i1 %r +} |
