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llvm-project/llvm/test/Transforms/InstCombine/strict-sub-underflow-check-...

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[NFC][InstCombine] Add tests for (X - Y) < X --> Y <= X iff Y != 0 https://rise4fun.com/Alive/KtL This should go to InstCombiner::foldICmpBinO(), next to "Convert sub-with-unsigned-overflow comparisons into a comparison of args." llvm-svn: 372911
2019-09-26 03:06:26 +08:00
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt %s -instcombine -S | FileCheck %s
declare void @llvm.assume(i1)
declare i8 @gen8()
declare void @use8(i8)
define i1 @t0(i8 %base, i8 %offset) {
; CHECK-LABEL: @t0(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[OFFSET:%.*]], 0
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET]]
; CHECK-NEXT: call void @use8(i8 [[ADJUSTED]])
[InstCombine] Fold (A - B) u>=/u< A --> B u>/u<= A iff B != 0 https://rise4fun.com/Alive/KtL This also shows that the fold added in D67412 / r372257 was too specific, and the new fold allows those test cases to be handled more generically, therefore i delete now-dead code. This is yet again motivated by D67122 "[UBSan][clang][compiler-rt] Applying non-zero offset to nullptr is undefined behaviour" llvm-svn: 372912
2019-09-26 03:06:40 +08:00
; CHECK-NEXT: [[RES:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
[NFC][InstCombine] Add tests for (X - Y) < X --> Y <= X iff Y != 0 https://rise4fun.com/Alive/KtL This should go to InstCombiner::foldICmpBinO(), next to "Convert sub-with-unsigned-overflow comparisons into a comparison of args." llvm-svn: 372911
2019-09-26 03:06:26 +08:00
; CHECK-NEXT: ret i1 [[RES]]
;
%cmp = icmp slt i8 %offset, 0
call void @llvm.assume(i1 %cmp)
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
%res = icmp ult i8 %adjusted, %base
ret i1 %res
}
define i1 @t1(i8 %base, i8 %offset) {
; CHECK-LABEL: @t1(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[OFFSET:%.*]], 0
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET]]
; CHECK-NEXT: call void @use8(i8 [[ADJUSTED]])
[InstCombine] Fold (A - B) u>=/u< A --> B u>/u<= A iff B != 0 https://rise4fun.com/Alive/KtL This also shows that the fold added in D67412 / r372257 was too specific, and the new fold allows those test cases to be handled more generically, therefore i delete now-dead code. This is yet again motivated by D67122 "[UBSan][clang][compiler-rt] Applying non-zero offset to nullptr is undefined behaviour" llvm-svn: 372912
2019-09-26 03:06:40 +08:00
; CHECK-NEXT: [[RES:%.*]] = icmp ult i8 [[BASE]], [[OFFSET]]
[NFC][InstCombine] Add tests for (X - Y) < X --> Y <= X iff Y != 0 https://rise4fun.com/Alive/KtL This should go to InstCombiner::foldICmpBinO(), next to "Convert sub-with-unsigned-overflow comparisons into a comparison of args." llvm-svn: 372911
2019-09-26 03:06:26 +08:00
; CHECK-NEXT: ret i1 [[RES]]
;
%cmp = icmp slt i8 %offset, 0
call void @llvm.assume(i1 %cmp)
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
%res = icmp uge i8 %adjusted, %base
ret i1 %res
}
define i1 @t2(i8 %offset) {
; CHECK-LABEL: @t2(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[OFFSET:%.*]], 0
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[BASE:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE]], [[OFFSET]]
; CHECK-NEXT: call void @use8(i8 [[ADJUSTED]])
[InstCombine] Fold (A - B) u>=/u< A --> B u>/u<= A iff B != 0 https://rise4fun.com/Alive/KtL This also shows that the fold added in D67412 / r372257 was too specific, and the new fold allows those test cases to be handled more generically, therefore i delete now-dead code. This is yet again motivated by D67122 "[UBSan][clang][compiler-rt] Applying non-zero offset to nullptr is undefined behaviour" llvm-svn: 372912
2019-09-26 03:06:40 +08:00
; CHECK-NEXT: [[RES:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
[NFC][InstCombine] Add tests for (X - Y) < X --> Y <= X iff Y != 0 https://rise4fun.com/Alive/KtL This should go to InstCombiner::foldICmpBinO(), next to "Convert sub-with-unsigned-overflow comparisons into a comparison of args." llvm-svn: 372911
2019-09-26 03:06:26 +08:00
; CHECK-NEXT: ret i1 [[RES]]
;
%cmp = icmp slt i8 %offset, 0
call void @llvm.assume(i1 %cmp)
%base = call i8 @gen8()
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
%res = icmp ugt i8 %base, %adjusted
ret i1 %res
}
define i1 @t3(i8 %offset) {
; CHECK-LABEL: @t3(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[OFFSET:%.*]], 0
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[BASE:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE]], [[OFFSET]]
; CHECK-NEXT: call void @use8(i8 [[ADJUSTED]])
[InstCombine] Fold (A - B) u>=/u< A --> B u>/u<= A iff B != 0 https://rise4fun.com/Alive/KtL This also shows that the fold added in D67412 / r372257 was too specific, and the new fold allows those test cases to be handled more generically, therefore i delete now-dead code. This is yet again motivated by D67122 "[UBSan][clang][compiler-rt] Applying non-zero offset to nullptr is undefined behaviour" llvm-svn: 372912
2019-09-26 03:06:40 +08:00
; CHECK-NEXT: [[RES:%.*]] = icmp ult i8 [[BASE]], [[OFFSET]]
[NFC][InstCombine] Add tests for (X - Y) < X --> Y <= X iff Y != 0 https://rise4fun.com/Alive/KtL This should go to InstCombiner::foldICmpBinO(), next to "Convert sub-with-unsigned-overflow comparisons into a comparison of args." llvm-svn: 372911
2019-09-26 03:06:26 +08:00
; CHECK-NEXT: ret i1 [[RES]]
;
%cmp = icmp slt i8 %offset, 0
call void @llvm.assume(i1 %cmp)
%base = call i8 @gen8()
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
%res = icmp ule i8 %base, %adjusted
ret i1 %res
}
; Here we don't know that offset is non-zero. Can't fold.
define i1 @n4_maybezero(i8 %base, i8 %offset) {
; CHECK-LABEL: @n4_maybezero(
; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
; CHECK-NEXT: call void @use8(i8 [[ADJUSTED]])
; CHECK-NEXT: [[RES:%.*]] = icmp ult i8 [[ADJUSTED]], [[BASE]]
; CHECK-NEXT: ret i1 [[RES]]
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
%res = icmp ult i8 %adjusted, %base
ret i1 %res
}
; We need to know that about %offset, %base won't do. Can't fold.
define i1 @n5_wrongnonzero(i8 %base, i8 %offset) {
; CHECK-LABEL: @n5_wrongnonzero(
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[BASE:%.*]], 0
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[ADJUSTED:%.*]] = sub i8 [[BASE]], [[OFFSET:%.*]]
; CHECK-NEXT: call void @use8(i8 [[ADJUSTED]])
; CHECK-NEXT: [[RES:%.*]] = icmp ult i8 [[ADJUSTED]], [[BASE]]
; CHECK-NEXT: ret i1 [[RES]]
;
%cmp = icmp sgt i8 %base, 0
call void @llvm.assume(i1 %cmp)
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
%res = icmp ult i8 %adjusted, %base
ret i1 %res
}