[llvm] r238452 - [InstCombine] Fold IntToPtr and PtrToInt into preceding loads.
Quentin Colombet via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 3 10:33:09 PST 2016
For the record, I think it has to do with type based alias analysis.
Q.
> On Feb 3, 2016, at 10:15 AM, Quentin Colombet via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>
> +llvm-commit
>> On Feb 3, 2016, at 10:14 AM, Quentin Colombet <qcolombet at apple.com <mailto:qcolombet at apple.com>> wrote:
>>
>> Hi David,
>>
>> Sorry to bring that commit up, but I’ve reverted it in r259674.
>> According to git bisect, this is the root cause of a miscompile in Regex.
>> I’ve put the detailed on how to reproduce in the commit message of r259674.
>>
>> I am working on reducing the test case (which right now is a bootstrap, then build llvm-extract with lto).
>>
>> I am guessing that the bug is not actually in this commit but exposes more opportunities to another optimization to go wrong.
>>
>> Anyhow, I’ve reverted it, because we have some internal bots that hit this now.
>>
>> Thanks,
>> -Quentin
>>
>>> On May 28, 2015, at 11:52 AM, David Majnemer <david.majnemer at gmail.com <mailto:david.majnemer at gmail.com>> wrote:
>>>
>>> Patch by Philip Pfaffe!
>>>
>>> On Thu, May 28, 2015 at 11:39 AM, David Majnemer <david.majnemer at gmail.com <mailto:david.majnemer at gmail.com>> wrote:
>>> Author: majnemer
>>> Date: Thu May 28 13:39:17 2015
>>> New Revision: 238452
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=238452&view=rev <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D238452-26view-3Drev&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=olNjq2h6jOqNEfp-gkn0gkdSmC_Cq2PIHP67QCufkSY&s=sY9wqRVuCtMcwCgMuzhFlmNBzaeMHGzxurg-FS2sE_w&e=>
>>> Log:
>>> [InstCombine] Fold IntToPtr and PtrToInt into preceding loads.
>>>
>>> Currently we only fold a BitCast into a Load when the BitCast is its
>>> only user.
>>>
>>> Do the same for any no-op cast.
>>>
>>> Differential Revision: http://reviews.llvm.org/D9152 <https://urldefense.proofpoint.com/v2/url?u=http-3A__reviews.llvm.org_D9152&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=olNjq2h6jOqNEfp-gkn0gkdSmC_Cq2PIHP67QCufkSY&s=0ErPMlQC5TI1p-lxa0ZTYmfyih7fQVsAo9kgeBsBiLo&e=>
>>>
>>> Added:
>>> llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll
>>> llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll
>>> Modified:
>>> llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
>>>
>>> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp?rev=238452&r1=238451&r2=238452&view=diff <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_Transforms_InstCombine_InstCombineLoadStoreAlloca.cpp-3Frev-3D238452-26r1-3D238451-26r2-3D238452-26view-3Ddiff&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=olNjq2h6jOqNEfp-gkn0gkdSmC_Cq2PIHP67QCufkSY&s=QM30wzxtVasww-Km95KLdBoCNDt_25E5FeFDPrMWQp4&e=>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp Thu May 28 13:39:17 2015
>>> @@ -483,12 +483,17 @@ static Instruction *combineLoadToOperati
>>> }
>>>
>>> // 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 *BC = dyn_cast<BitCastInst>(LI.user_back())) {
>>> - LoadInst *NewLoad = combineLoadToNewType(IC, LI, BC->getDestTy());
>>> - BC->replaceAllUsesWith(NewLoad);
>>> - IC.EraseInstFromFunction(*BC);
>>> - return &LI;
>>> + 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;
>>> + }
>>> }
>>>
>>> // FIXME: We should also canonicalize loads of vectors when their elements are
>>>
>>> Added: llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll?rev=238452&view=auto <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_test_Transforms_InstCombine_load-2Dbitcast32.ll-3Frev-3D238452-26view-3Dauto&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=olNjq2h6jOqNEfp-gkn0gkdSmC_Cq2PIHP67QCufkSY&s=NrPn-jA9V0ieNNsVOi8wYa31xU_WEeNqb6Qk8C4cnJA&e=>
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll (added)
>>> +++ llvm/trunk/test/Transforms/InstCombine/load-bitcast32.ll Thu May 28 13:39:17 2015
>>> @@ -0,0 +1,79 @@
>>> +; 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
>>> +}
>>> +
>>>
>>> Added: llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll?rev=238452&view=auto <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_test_Transforms_InstCombine_load-2Dbitcast64.ll-3Frev-3D238452-26view-3Dauto&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=olNjq2h6jOqNEfp-gkn0gkdSmC_Cq2PIHP67QCufkSY&s=Ct7qAC1oyddLnff8X5WXL8bZlU4kgWSD4P7ZT45sFt8&e=>
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll (added)
>>> +++ llvm/trunk/test/Transforms/InstCombine/load-bitcast64.ll Thu May 28 13:39:17 2015
>>> @@ -0,0 +1,78 @@
>>> +; 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
>>> +}
>>> +
>>>
>>>
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>>
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