[PATCH] D20319: [InstCombine] Fix assertion when bitcast is converted to gep

[Gerolf Hoflehner via llvm-commits]

Committed revision 270479

Thanks, David!

> On May 16, 2016, at 11:37 PM, Gerolf Hoflehner <ghoflehner at apple.com> wrote:
> 
> Gerolf created this revision.
> Gerolf added a reviewer: llvm-commits.
> 
> When an aggregate contains an opaque type its size cannot be
> determined. This triggers an "Invalid GetElementPtrInst indices for type" assert
> in function checkGEPType. The patch suppresses the conversion in this case.
> 
> http://reviews.llvm.org/D20319
> 
> Files:
>  lib/Transforms/InstCombine/InstCombineCasts.cpp
>  test/Transforms/InstCombine/opaque.ll
> 
> Index: test/Transforms/InstCombine/opaque.ll
> ===================================================================
> --- /dev/null
> +++ test/Transforms/InstCombine/opaque.ll
> @@ -0,0 +1,32 @@
> +; RUN: opt < %s -instcombine -disable-output
> +; Checks that bitcasts are not converted into GEP when
> +; when the size of an aggregate cannot be determined.
> +%swift.opaque = type opaque
> +%SQ = type <{ [8 x i8] }>
> +%Si = type <{ i64 }>
> +
> +%V = type <{ <{ %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8, %Vs4Int8 }>, %Si, %SQ, %SQ, %Si, %swift.opaque }>
> +%Vs4Int8 = type <{ i8 }>
> +%swift.type = type { i64 }
> +
> +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly,
> +i64, i32, i1) #8
> +
> + at _swift_slowAlloc = external global i8* (i64, i64)*
> +
> +declare i8* @rt_swift_slowAlloc(i64, i64)
> +
> +define  %swift.opaque* @_TwTkV([24 x i8]* %dest, %swift.opaque* %src,
> +%swift.type* %bios_boot_params) #0 {
> +entry:
> +  %0 = bitcast %swift.opaque* %src to %V*
> +  %1 = call noalias i8* @rt_swift_slowAlloc(i64 40, i64 0) #11
> +  %2 = bitcast [24 x i8]* %dest to i8**
> +  store i8* %1, i8** %2, align 8
> +  %3 = bitcast i8* %1 to %V*
> +  %4 = bitcast %V* %3 to i8*
> +  %5 = bitcast %V* %0 to i8*
> +  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %4, i8* %5, i64 40, i32 1, i1 false)
> +  %6 = bitcast %V* %3 to %swift.opaque*
> +  ret %swift.opaque* %6
> +}
> Index: lib/Transforms/InstCombine/InstCombineCasts.cpp
> ===================================================================
> --- lib/Transforms/InstCombine/InstCombineCasts.cpp
> +++ lib/Transforms/InstCombine/InstCombineCasts.cpp
> @@ -1915,6 +1915,11 @@
>       if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
>         return V;
> 
> +    Type *PointeeType =
> +        cast<PointerType>(Src->getType()->getScalarType())->getElementType();
> +    if (!PointeeType->isSized())
> +      return nullptr;
> +
>     // If the source and destination are pointers, and this cast is equivalent
>     // to a getelementptr X, 0, 0, 0...  turn it into the appropriate gep.
>     // This can enhance SROA and other transforms that want type-safe pointers.
> 
> 
> <D20319.57435.patch>

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