[llvm] r363743 - Recommit [SROA] Enhance SROA to handle `addrspacecast`ed allocas

[Matt Arsenault via llvm-commits]

Needs another test that hits the regression

> On Jun 18, 2019, at 5:41 PM, Michael Liao via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Author: hliao
> Date: Tue Jun 18 14:41:13 2019
> New Revision: 363743
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=363743&view=rev
> Log:
> Recommit [SROA] Enhance SROA to handle `addrspacecast`ed allocas
> 
> [SROA] Enhance SROA to handle `addrspacecast`ed allocas
> 
> - Fix typo in original change
> - Add additional handling to ensure all return pointers are properly
>  casted.
> 
> Summary:
> - After `addrspacecast` is allowed to be eliminated in SROA, the
>  adjusting of storage pointer (from `alloca) needs to handle the
>  potential different address spaces between the storage pointer (from
>  alloca) and the pointer being used.
> 
> Reviewers: arsenm
> 
> Subscribers: wdng, hiraditya, llvm-commits
> 
> Tags: #llvm
> 
> Differential Revision: https://reviews.llvm.org/D63501
> 
> Modified:
>    llvm/trunk/lib/Transforms/Scalar/SROA.cpp
>    llvm/trunk/test/Transforms/SROA/addrspacecast.ll
> 
> Modified: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SROA.cpp?rev=363743&r1=363742&r2=363743&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SROA.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp Tue Jun 18 14:41:13 2019
> @@ -1589,6 +1589,12 @@ static Value *getAdjustedPtr(IRBuilderTy
>   PointerType *TargetPtrTy = cast<PointerType>(PointerTy);
>   Type *TargetTy = TargetPtrTy->getElementType();
> 
> +  // As `addrspacecast` is , `Ptr` (the storage pointer) may have different
> +  // address space from the expected `PointerTy` (the pointer to be used).
> +  // Adjust the pointer type based the original storage pointer.
> +  auto AS = cast<PointerType>(Ptr->getType())->getAddressSpace();
> +  PointerTy = TargetTy->getPointerTo(AS);
> +
>   do {
>     // First fold any existing GEPs into the offset.
>     while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
> @@ -1617,7 +1623,7 @@ static Value *getAdjustedPtr(IRBuilderTy
>       OffsetBasePtr = Ptr;
>       // If we also found a pointer of the right type, we're done.
>       if (P->getType() == PointerTy)
> -        return P;
> +        break;
>     }
> 
>     // Stash this pointer if we've found an i8*.
> 
> Modified: llvm/trunk/test/Transforms/SROA/addrspacecast.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SROA/addrspacecast.ll?rev=363743&r1=363742&r2=363743&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SROA/addrspacecast.ll (original)
> +++ llvm/trunk/test/Transforms/SROA/addrspacecast.ll Tue Jun 18 14:41:13 2019
> @@ -299,6 +299,21 @@ define void @select_addrspacecast_gv(i1
>   ret void
> }
> 
> +; CHECK-LABEL: @select_addrspacecast_i8(
> +; CHECK: [[SEL:%.*]] = select i1 undef, i8 undef, i8 undef
> +; CHECK-NEXT: ret i8 [[SEL]]
> +define i8 @select_addrspacecast_i8() {
> +  %a = alloca i8
> +  %b = alloca i8
> +
> +  %a.ptr = addrspacecast i8* %a to i8 addrspace(1)*
> +  %b.ptr = addrspacecast i8* %b to i8 addrspace(1)*
> +
> +  %ptr = select i1 undef, i8 addrspace(1)* %a.ptr, i8 addrspace(1)* %b.ptr
> +  %ret = load i8, i8 addrspace(1)* %ptr
> +  ret i8 %ret
> +}
> +
> !0 = !{!1, !1, i64 0, i64 1}
> !1 = !{!2, i64 1, !"type_0"}
> !2 = !{!"root"}
> 
> 
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