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[NFC][InstCombine] Add tests for (X - Y) < X --> Y <= X iff Y != 0

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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
This commit is contained in:
Roman Lebedev 2019-09-25 19:06:26 +00:00
parent acacd8b14d
commit be4f24e7de
1 changed files with 111 additions and 0 deletions
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111
test/Transforms/InstCombine/strict-sub-underflow-check-to-comparison-of-sub-operands.ll Normal file
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; 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]])
; CHECK-NEXT: [[RES:%.*]] = icmp ult i8 [[ADJUSTED]], [[BASE]]
; 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]])
; CHECK-NEXT: [[RES:%.*]] = icmp uge i8 [[ADJUSTED]], [[BASE]]
; 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]])
; CHECK-NEXT: [[RES:%.*]] = icmp ugt i8 [[BASE]], [[ADJUSTED]]
; 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]])
; CHECK-NEXT: [[RES:%.*]] = icmp ule i8 [[BASE]], [[ADJUSTED]]
; 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
}