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[InstSimplify] Fold gep (gep V, C), (xor V, -1) to C-1

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llvm-svn: 278779
This commit is contained in:
David Majnemer 2016-08-16 06:13:46 +00:00
parent d3333b5982
commit 4ca4b42bf0
3 changed files with 34 additions and 14 deletions
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8
lib/Analysis/InstructionSimplify.cpp
View File

@ -3645,7 +3645,6 @@ static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
}
}
// gep (gep V, C), (sub 0, V) -> C
if (Q.DL.getTypeAllocSize(LastType) == 1 &&
all_of(Ops.slice(1).drop_back(1),
[](Value *Idx) { return match(Idx, m_Zero()); })) {
@ -3657,11 +3656,18 @@ static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL,
BasePtrOffset);
// gep (gep V, C), (sub 0, V) -> C
if (match(Ops.back(),
m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr))))) {
auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
return ConstantExpr::getIntToPtr(CI, GEPTy);
}
// gep (gep V, C), (xor V, -1) -> C-1
if (match(Ops.back(),
m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes()))) {
auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
return ConstantExpr::getIntToPtr(CI, GEPTy);
}
}
}

27
test/Transforms/InstSimplify/cast.ll
View File

@ -1,4 +1,5 @@
; RUN: opt -S -instsimplify < %s | FileCheck %s
target datalayout = "p:32:32"
define i1 @test1(i1 %V) {
entry:
@ -25,3 +26,29 @@ entry:
; CHECK-LABEL: define i8* @test3(
; CHECK: ret i8* %V
}
define i32 @test4() {
; CHECK-LABEL: @test4(
%alloca = alloca i32, align 4 ; alloca + 0
%gep = getelementptr inbounds i32, i32* %alloca, i32 1 ; alloca + 4
%bc = bitcast i32* %gep to [4 x i8]* ; alloca + 4
%pti = ptrtoint i32* %alloca to i32 ; alloca
%sub = sub i32 0, %pti ; -alloca
%add = getelementptr [4 x i8], [4 x i8]* %bc, i32 0, i32 %sub ; alloca + 4 - alloca == 4
%add_to_int = ptrtoint i8* %add to i32 ; 4
ret i32 %add_to_int ; 4
; CHECK-NEXT: ret i32 4
}
define i32 @test5() {
; CHECK-LABEL: @test5(
%alloca = alloca i32, align 4 ; alloca + 0
%gep = getelementptr inbounds i32, i32* %alloca, i32 1 ; alloca + 4
%bc = bitcast i32* %gep to [4 x i8]* ; alloca + 4
%pti = ptrtoint i32* %alloca to i32 ; alloca
%sub = xor i32 %pti, -1 ; ~alloca
%add = getelementptr [4 x i8], [4 x i8]* %bc, i32 0, i32 %sub ; alloca + 4 - alloca - 1 == 3
%add_to_int = ptrtoint i8* %add to i32 ; 4
ret i32 %add_to_int ; 4
; CHECK-NEXT: ret i32 3
}

13
test/Transforms/InstSimplify/compare.ll
View File

@ -219,19 +219,6 @@ define i1 @gep17() {
; CHECK-NEXT: ret i1 true
}
define i32 @gep18() {
; CHECK-LABEL: @gep18(
%alloca = alloca i32, align 4 ; alloca + 0
%gep = getelementptr inbounds i32, i32* %alloca, i32 1 ; alloca + 4
%bc = bitcast i32* %gep to [4 x i8]* ; alloca + 4
%pti = ptrtoint i32* %alloca to i32 ; alloca
%sub = sub i32 0, %pti ; -alloca
%add = getelementptr [4 x i8], [4 x i8]* %bc, i32 0, i32 %sub ; alloca + 4 - alloca == 4
%add_to_int = ptrtoint i8* %add to i32 ; 4
ret i32 %add_to_int ; 4
; CHECK-NEXT: ret i32 4
}
define i1 @zext(i32 %x) {
; CHECK-LABEL: @zext(
%e1 = zext i32 %x to i64