[llvm] r276827 - [ConstantFolding] Correctly handle failures in ConstantFoldConstantExpressionImpl

[Hans Wennborg via llvm-commits]

Ping?

On Thu, Jul 28, 2016 at 9:00 AM, Hans Wennborg <hans at chromium.org> wrote:
> Should this be merged to 3.9?
>
> Cheers,
> Hans
>
> On Tue, Jul 26, 2016 at 7:39 PM, David Majnemer via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Author: majnemer
>> Date: Tue Jul 26 21:39:16 2016
>> New Revision: 276827
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=276827&view=rev
>> Log:
>> [ConstantFolding] Correctly handle failures in ConstantFoldConstantExpressionImpl
>>
>> Failures in ConstantFoldConstantExpressionImpl were ignored causing
>> crashes down the line.
>>
>> This fixes PR28725.
>>
>> Added:
>>     llvm/trunk/test/Transforms/InstSimplify/pr28725.ll
>> Modified:
>>     llvm/trunk/lib/Analysis/ConstantFolding.cpp
>>
>> Modified: llvm/trunk/lib/Analysis/ConstantFolding.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ConstantFolding.cpp?rev=276827&r1=276826&r2=276827&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Analysis/ConstantFolding.cpp (original)
>> +++ llvm/trunk/lib/Analysis/ConstantFolding.cpp Tue Jul 26 21:39:16 2016
>> @@ -1007,8 +1007,12 @@ Constant *llvm::ConstantFoldInstruction(
>>    for (const Use &OpU : I->operands()) {
>>      auto *Op = cast<Constant>(&OpU);
>>      // Fold the Instruction's operands.
>> -    if (auto *NewCE = dyn_cast<ConstantExpr>(Op))
>> -      Op = ConstantFoldConstantExpression(NewCE, DL, TLI);
>> +    if (auto *NewCE = dyn_cast<ConstantExpr>(Op)) {
>> +      auto *FoldedOp = ConstantFoldConstantExpression(NewCE, DL, TLI);
>> +      if (!FoldedOp)
>> +        return nullptr;
>> +      Op = FoldedOp;
>> +    }
>>
>>      Ops.push_back(Op);
>>    }
>> @@ -1048,8 +1052,13 @@ ConstantFoldConstantExpressionImpl(const
>>      // Recursively fold the ConstantExpr's operands. If we have already folded
>>      // a ConstantExpr, we don't have to process it again.
>>      if (auto *NewCE = dyn_cast<ConstantExpr>(NewC)) {
>> -      if (FoldedOps.insert(NewCE).second)
>> -        NewC = ConstantFoldConstantExpressionImpl(NewCE, DL, TLI, FoldedOps);
>> +      if (FoldedOps.insert(NewCE).second){
>> +        auto *FoldedC =
>> +            ConstantFoldConstantExpressionImpl(NewCE, DL, TLI, FoldedOps);
>> +        if (!FoldedC)
>> +          return nullptr;
>> +        NewC = FoldedC;
>> +      }
>>      }
>>      Ops.push_back(NewC);
>>    }
>>
>> Added: llvm/trunk/test/Transforms/InstSimplify/pr28725.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/pr28725.ll?rev=276827&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/InstSimplify/pr28725.ll (added)
>> +++ llvm/trunk/test/Transforms/InstSimplify/pr28725.ll Tue Jul 26 21:39:16 2016
>> @@ -0,0 +1,14 @@
>> +; RUN: opt -S -instsimplify < %s | FileCheck %s
>> +target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
>> +target triple = "x86_64-pc-windows-msvc"
>> +%S = type { i16, i32 }
>> +
>> +define <2 x i16> @test1() {
>> +entry:
>> +  %b = insertelement <2 x i16> <i16 undef, i16 0>, i16 extractvalue (%S select (i1 icmp eq (i16 extractelement (<2 x i16> bitcast (<1 x i32> <i32 1> to <2 x i16>), i32 0), i16 0), %S zeroinitializer, %S { i16 0, i32 1 }), 0), i32 0
>> +  ret <2 x i16> %b
>> +}
>> +
>> +; CHECK-LABEL: @test1(
>> +; CHECK: %[[ie:.*]] = insertelement <2 x i16> <i16 undef, i16 0>, i16 extractvalue (%S select (i1 icmp eq (i16 extractelement (<2 x i16> bitcast (<1 x i32> <i32 1> to <2 x i16>), i32 0), i16 0), %S zeroinitializer, %S { i16 0, i32 1 }), 0), i32 0
>> +; CHECK: ret <2 x i16> %[[ie]]
>>
>>
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