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

[Hans Wennborg via llvm-commits]

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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