[llvm-commits] PATCH: Fix bug in DAGCombiner generating illegal vector INT_TO_FP nodes

[Tom Stellard]

Ping.

On Fri, Dec 21, 2012 at 08:25:38AM -0800, Tom Stellard wrote:
> Hi,
> 
> The attached patch fixes a bug in
> DAGCombiner::reduceBuildVecConvertToConvertBuildVec() where
> the legality of vector INT_TO_FP and UINT_TO_FP operations was not being
> checked correctly.
> 
> The test case X86/cvtv2f32.ll, which was added in the same commit that introduces
> the bug now fails with this bug fix, so this patch marks it as xfail.
> I took a quick look at this test, but I couldn't figure out how to fix it.
> I did notice, however, that X86ISelLowering.cpp does this:
> 
> setOperationAction(ISD::UINT_TO_FP,       MVT::v2f32, Custom);
> 
> which is wrong. it should probably be v2i32 instead, but changing this
> did not fix the X86/cvtv2f32.ll test.
> 
> -Tom

> diff --git lib/CodeGen/SelectionDAG/DAGCombiner.cpp lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> index c852c06..2ff5650 100644
> --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> +++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> @@ -8624,11 +8624,8 @@ SDValue DAGCombiner::reduceBuildVecConvertToConvertBuildVec(SDNode *N) {
>      if (Opcode == ISD::DELETED_NODE &&
>          (Opc == ISD::UINT_TO_FP || Opc == ISD::SINT_TO_FP)) {
>        Opcode = Opc;
> -      // If not supported by target, bail out.
> -      if (TLI.getOperationAction(Opcode, VT) != TargetLowering::Legal &&
> -          TLI.getOperationAction(Opcode, VT) != TargetLowering::Custom)
> -        return SDValue();
>      }
> +
>      if (Opc != Opcode)
>        return SDValue();
>  
> @@ -8653,6 +8650,11 @@ SDValue DAGCombiner::reduceBuildVecConvertToConvertBuildVec(SDNode *N) {
>    assert(SrcVT != MVT::Other && "Cannot determine source type!");
>  
>    EVT NVT = EVT::getVectorVT(*DAG.getContext(), SrcVT, NumInScalars);
> +
> +  if (!TLI.isOperationLegalOrCustom(Opcode, NVT)) {
> +    return SDValue();
> +  }
> +
>    SmallVector<SDValue, 8> Opnds;
>    for (unsigned i = 0; i != NumInScalars; ++i) {
>      SDValue In = N->getOperand(i);
> diff --git test/CodeGen/R600/dagcombiner-bug-illegal-vec4-int-to-fp.ll test/CodeGen/R600/dagcombiner-bug-illegal-vec4-int-to-fp.ll
> new file mode 100644
> index 0000000..1acf905
> --- /dev/null
> +++ test/CodeGen/R600/dagcombiner-bug-illegal-vec4-int-to-fp.ll
> @@ -0,0 +1,33 @@
> +;RUN: llc < %s -march=r600 -mcpu=redwood | FileCheck %s
> +
> +;CHECK: INT_TO_FLT T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}
> +
> +; This test is for a bug in
> +; DAGCombiner::reduceBuildVecConvertToConvertBuildVec() where
> +; the wrong type was being passed to
> +; TargetLowering::getOperationAction() when checking the legality of
> +; ISD::UINT_TO_FP and ISD::SINT_TO_FP opcodes.
> +
> +define void @sint(<4 x float> addrspace(1)* %out, i32 addrspace(1)* %in) {
> +entry:
> +  %ptr = getelementptr i32 addrspace(1)* %in, i32 1
> +  %sint = load i32 addrspace(1) * %in
> +  %conv = sitofp i32 %sint to float
> +  %0 = insertelement <4 x float> undef, float %conv, i32 0
> +  %splat = shufflevector <4 x float> %0, <4 x float> undef, <4 x i32> zeroinitializer
> +  store <4 x float> %splat, <4 x float> addrspace(1)* %out
> +  ret void
> +}
> +
> +;CHECK: UINT_TO_FLT T{{[0-9]+\.[XYZW], T[0-9]+\.[XYZW]}}
> +
> +define void @uint(<4 x float> addrspace(1)* %out, i32 addrspace(1)* %in) {
> +entry:
> +  %ptr = getelementptr i32 addrspace(1)* %in, i32 1
> +  %uint = load i32 addrspace(1) * %in
> +  %conv = uitofp i32 %uint to float
> +  %0 = insertelement <4 x float> undef, float %conv, i32 0
> +  %splat = shufflevector <4 x float> %0, <4 x float> undef, <4 x i32> zeroinitializer
> +  store <4 x float> %splat, <4 x float> addrspace(1)* %out
> +  ret void
> +}
> diff --git test/CodeGen/X86/cvtv2f32.ll test/CodeGen/X86/cvtv2f32.ll
> index 466b096..d11bb9e 100644
> --- test/CodeGen/X86/cvtv2f32.ll
> +++ test/CodeGen/X86/cvtv2f32.ll
> @@ -1,3 +1,7 @@
> +; A bug fix in the DAGCombiner made this test fail, so marking as xfail
> +; until this can be investigated further.
> +; XFAIL: *
> +
>  ; RUN: llc < %s -mtriple=i686-linux-pc -mcpu=corei7 | FileCheck %s
>  
>  define <2 x float> @foo(i32 %x, i32 %y, <2 x float> %v) {

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