[PATCH] Fix always creating GEP with i32 indices

[Eli Friedman]

The code change is fine, I guess.  I'm not sure your test is actually
testing anything useful given the current architecture of instcombine;
even if we build a GEP with wrong-sized indices, the GEP visitor will
fix it.

-Eli

On Mon, Aug 12, 2013 at 5:15 PM, Matt Arsenault
<Matthew.Arsenault at amd.com> wrote:
> Hi eli.friedman,
>
> Use the pointer size if datalayout is available. Use i64 if it's not, which is consistent with what other places do when the pointer size is unknown.
>
> http://llvm-reviews.chandlerc.com/D1372
>
> Files:
>   lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
>   test/Transforms/InstCombine/alloca.ll
>
> Index: lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
> ===================================================================
> --- lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
> +++ lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
> @@ -180,7 +180,10 @@
>        // Now that I is pointing to the first non-allocation-inst in the block,
>        // insert our getelementptr instruction...
>        //
> -      Value *NullIdx = Constant::getNullValue(Type::getInt32Ty(AI.getContext()));
> +      Type *IdxTy = TD
> +                  ? TD->getIntPtrType(AI.getContext())
> +                  : Type::getInt64Ty(AI.getContext());
> +      Value *NullIdx = Constant::getNullValue(IdxTy);
>        Value *Idx[2] = { NullIdx, NullIdx };
>        Instruction *GEP =
>          GetElementPtrInst::CreateInBounds(New, Idx, New->getName() + ".sub");
> Index: test/Transforms/InstCombine/alloca.ll
> ===================================================================
> --- test/Transforms/InstCombine/alloca.ll
> +++ test/Transforms/InstCombine/alloca.ll
> @@ -1,7 +1,7 @@
> -target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
> +; RUN: opt < %s -instcombine -S -default-data-layout="E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128" | FileCheck %s
> +; RUN: opt < %s -instcombine -S -default-data-layout="E-p:32:32:32-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128" | FileCheck %s -check-prefix=P32
> +; RUN: opt < %s -instcombine -S | FileCheck %s -check-prefix=NODL
>
> -; RUN: opt < %s -instcombine -S | FileCheck %s
> -; END.
>
>  declare void @use(...)
>
> @@ -110,3 +110,22 @@
>  }
>
>  declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
> +
> +
> +; Check that the GEP indices use the pointer size, or 64 if unknown
> +define void @test8() {
> +; CHECK-LABEL: @test8(
> +; CHECK: alloca [100 x i32]
> +; CHECK: getelementptr inbounds [100 x i32]* %x1, i64 0, i64 0
> +
> +; P32-LABEL: @test8(
> +; P32: alloca [100 x i32]
> +; P32: getelementptr inbounds [100 x i32]* %x1, i32 0, i32 0
> +
> +; NODL-LABEL: @test8(
> +; NODL: alloca [100 x i32]
> +; NODL: getelementptr inbounds [100 x i32]* %x1, i64 0, i64 0
> +  %x = alloca i32, i32 100
> +  call void (...)* @use(i32* %x)
> +  ret void
> +}