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

[David Majnemer via llvm-commits]

No, this is not a regression; the oldest LLVM I have, 3.4, fails with the
exact same test case.  Trunk has a more comprehensive series of commits
which really fix this bug.

On Mon, Aug 1, 2016 at 1:38 PM, Hans Wennborg <hans at chromium.org> wrote:

> 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]]
> >>
> >>
> >> _______________________________________________
> >> llvm-commits mailing list
> >> llvm-commits at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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