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[InstCombine] Revert r238452: Fold IntToPtr and PtrToInt into preceding loads.

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According to git bisect, this is the root cause of a miscompile for Regex in
libLLVMSupport. I am still working on reducing a test case.
The actual bug may be elsewhere and this commit just exposed it.

Anyway, at the moment, to reproduce, follow these steps:
1. Build clang and libLTO in release mode.
2. Create a new build directory <stage2> and cd into it.
3. Use clang and libLTO from #1 to build llvm-extract in Release mode + asserts
   using -O2 -flto
4. Run llvm-extract  -ralias '.*bar' -S test/Other/extract-alias.ll

Result:
program doesn't contain global named '.*bar'!

Expected result:
@a0a0bar = alias void ()* @bar
@a0bar = alias void ()* @bar

declare void @bar()

Note: In step #3, if you don't use lto or asserts, the miscompile disappears.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259674 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2016-02-03 18:04:13 +00:00
parent 8e9339f574
commit 185966c650
4 changed files with 7 additions and 169 deletions
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15
lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
View File

@ -495,17 +495,12 @@ static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) {
}
// Fold away bit casts of the loaded value by loading the desired type.
// We can do this for BitCastInsts as well as casts from and to pointer types,
// as long as those are noops (i.e., the source or dest type have the same
// bitwidth as the target's pointers).
if (LI.hasOneUse())
if (auto* CI = dyn_cast<CastInst>(LI.user_back())) {
if (CI->isNoopCast(DL)) {
LoadInst *NewLoad = combineLoadToNewType(IC, LI, CI->getDestTy());
CI->replaceAllUsesWith(NewLoad);
IC.eraseInstFromFunction(*CI);
return &LI;
}
if (auto *BC = dyn_cast<BitCastInst>(LI.user_back())) {
LoadInst *NewLoad = combineLoadToNewType(IC, LI, BC->getDestTy());
BC->replaceAllUsesWith(NewLoad);
IC.eraseInstFromFunction(*BC);
return &LI;
}
// FIXME: We should also canonicalize loads of vectors when their elements are

79
test/Transforms/InstCombine/load-bitcast32.ll
View File

@ -1,79 +0,0 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
target datalayout = "p:32:32:32"
define i64* @test1(i8* %x) {
entry:
; CHECK-LABEL: @test1(
; CHECK: load i64, i64*
; CHECK: ret
%a = bitcast i8* %x to i64*
%b = load i64, i64* %a
%c = inttoptr i64 %b to i64*
ret i64* %c
}
define i32* @test2(i8* %x) {
entry:
; CHECK-LABEL: @test2(
; CHECK: load i32*, i32**
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i32*
ret i32* %c
}
define i64* @test3(i8* %x) {
entry:
; CHECK-LABEL: @test3(
; CHECK: load i64*, i64**
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i64*
ret i64* %c
}
define i64 @test4(i8* %x) {
entry:
; CHECK-LABEL: @test4(
; CHECK: load i32, i32*
; CHECK: zext
; CHECK: ret
%a = bitcast i8* %x to i64**
%b = load i64*, i64** %a
%c = ptrtoint i64* %b to i64
ret i64 %c
}
define i32 @test5(i8* %x) {
entry:
; CHECK-LABEL: @test5(
; CHECK: load i32, i32*
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i32
ret i32 %c
}
define i64 @test6(i8* %x) {
entry:
; CHECK-LABEL: @test6(
; CHECK: load i32, i32*
; CHECK: zext
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i64
ret i64 %c
}

78
test/Transforms/InstCombine/load-bitcast64.ll
View File

@ -1,78 +0,0 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
target datalayout = "p:64:64:64"
define i64* @test1(i8* %x) {
entry:
; CHECK-LABEL: @test1(
; CHECK: load i64*, i64**
; CHECK: ret
%a = bitcast i8* %x to i64*
%b = load i64, i64* %a
%c = inttoptr i64 %b to i64*
ret i64* %c
}
define i32* @test2(i8* %x) {
entry:
; CHECK-LABEL: @test2(
; CHECK: load i32, i32*
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i32*
ret i32* %c
}
define i64* @test3(i8* %x) {
entry:
; CHECK-LABEL: @test3(
; CHECK: load i32, i32*
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i64*
ret i64* %c
}
define i64 @test4(i8* %x) {
entry:
; CHECK-LABEL: @test4(
; CHECK: load i64, i64*
; CHECK: ret
%a = bitcast i8* %x to i64**
%b = load i64*, i64** %a
%c = ptrtoint i64* %b to i64
ret i64 %c
}
define i32 @test5(i8* %x) {
entry:
; CHECK-LABEL: @test5(
; CHECK: load i64, i64*
; CHECK: trunc
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i32
ret i32 %c
}
define i64 @test6(i8* %x) {
entry:
; CHECK-LABEL: @test6(
; CHECK: load i64, i64*
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i64
ret i64 %c
}

4
test/Transforms/InstCombine/memset_chk-1.ll
View File

@ -72,14 +72,14 @@ entry:
%yo107 = call i64 @llvm.objectsize.i64.p0i8(i8* %b, i1 false)
%call50 = call i8* @__memmove_chk(i8* %b, i8* %a, i64 %add180, i64 %yo107)
; CHECK: %strlen = call i64 @strlen(i8* %b)
; CHECK-NEXT: %strchr2 = getelementptr i8, i8* %b, i64 %strlen
; CHECK-NEXT: [[STRCHR:%[0-9a-zA-Z_-]+]] = getelementptr i8, i8* %b, i64 %strlen
%call51i = call i8* @strrchr(i8* %b, i32 0)
%d = load i8*, i8** %c, align 8
%sub182 = ptrtoint i8* %d to i64
%sub183 = ptrtoint i8* %b to i64
%sub184 = sub i64 %sub182, %sub183
%add52.i.i = add nsw i64 %sub184, 1
; CHECK: call void @llvm.memset.p0i8.i64(i8* %strchr2
; CHECK: call void @llvm.memset.p0i8.i64(i8* [[STRCHR]]
%call185 = call i8* @__memset_chk(i8* %call51i, i32 0, i64 %add52.i.i, i64 -1)
ret i32 4
}