[llvm] r239539 - Fix merges of non-zero vector stores

Reid Kleckner rnk at google.com
Thu Jun 11 10:20:22 PDT 2015


We're getting this assertion in the blame range 239540 - 239539 inclusive,
so I'm pretty sure it's this change:
SelectionDAG.cpp:756: void VerifySDNode(llvm::SDNode*): Assertion
`N->getNumOperands() == N->getValueType(0).getVectorNumElements() && "Wrong
number of operands!"' failed.

This is while building freetype as part of chromium:
http://build.chromium.org/p/chromium.fyi/builders/ClangToTLinux/builds/1809/steps/compile/logs/stdio

Do you think you can spot the problem, or do you want me to try to reduce a
test case?

On Thu, Jun 11, 2015 at 9:03 AM, Matt Arsenault <Matthew.Arsenault at amd.com>
wrote:

> Author: arsenm
> Date: Thu Jun 11 11:03:52 2015
> New Revision: 239539
>
> URL: http://llvm.org/viewvc/llvm-project?rev=239539&view=rev
> Log:
> Fix merges of non-zero vector stores
>
> Now actually stores the non-zero constant instead of 0.
> I somehow forgot to include this part of r238108.
>
> The test change was just an independent instruction order swap,
> so just add another check line to satisfy CHECK-NEXT.
>
> Modified:
>     llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>     llvm/trunk/test/CodeGen/R600/merge-stores.ll
>     llvm/trunk/test/CodeGen/X86/2012-11-28-merge-store-alias.ll
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=239539&r1=239538&r2=239539&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Jun 11
> 11:03:52 2015
> @@ -387,6 +387,13 @@ namespace {
>        unsigned SequenceNum;
>      };
>
> +    /// This is a helper function for MergeStoresOfConstantsOrVecElts.
> Returns a
> +    /// constant build_vector of the stored constant values in Stores.
> +    SDValue getMergedConstantVectorStore(SelectionDAG &DAG,
> +                                         SDLoc SL,
> +                                         ArrayRef<MemOpLink> Stores,
> +                                         EVT Ty) const;
> +
>      /// This is a helper function for MergeConsecutiveStores. When the
> source
>      /// elements of the consecutive stores are all constants or all
> extracted
>      /// vector elements, try to merge them into one larger store.
> @@ -10576,6 +10583,17 @@ struct BaseIndexOffset {
>  };
>  } // namespace
>
> +SDValue DAGCombiner::getMergedConstantVectorStore(SelectionDAG &DAG,
> +                                                  SDLoc SL,
> +                                                  ArrayRef<MemOpLink>
> Stores,
> +                                                  EVT Ty) const {
> +  SmallVector<SDValue, 8> BuildVector;
> +
> +  for (const MemOpLink &Store : Stores)
> +    BuildVector.push_back(cast<StoreSDNode>(Store.MemNode)->getValue());
> +  return DAG.getNode(ISD::BUILD_VECTOR, SL, Ty, BuildVector);
> +}
> +
>  bool DAGCombiner::MergeStoresOfConstantsOrVecElts(
>                    SmallVectorImpl<MemOpLink> &StoreNodes, EVT MemVT,
>                    unsigned NumElem, bool IsConstantSrc, bool UseVector) {
> @@ -10606,12 +10624,7 @@ bool DAGCombiner::MergeStoresOfConstants
>      EVT Ty = EVT::getVectorVT(*DAG.getContext(), MemVT, NumElem);
>      assert(TLI.isTypeLegal(Ty) && "Illegal vector store");
>      if (IsConstantSrc) {
> -      // A vector store with a constant source implies that the constant
> is
> -      // zero; we only handle merging stores of constant zeros because
> the zero
> -      // can be materialized without a load.
> -      // It may be beneficial to loosen this restriction to allow non-zero
> -      // store merging.
> -      StoredVal = DAG.getConstant(0, DL, Ty);
> +      StoredVal = getMergedConstantVectorStore(DAG, DL, StoreNodes, Ty);
>      } else {
>        SmallVector<SDValue, 8> Ops;
>        for (unsigned i = 0; i < NumElem ; ++i) {
>
> Modified: llvm/trunk/test/CodeGen/R600/merge-stores.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/R600/merge-stores.ll?rev=239539&r1=239538&r2=239539&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/CodeGen/R600/merge-stores.ll (original)
> +++ llvm/trunk/test/CodeGen/R600/merge-stores.ll Thu Jun 11 11:03:52 2015
> @@ -89,7 +89,11 @@ define void @merge_global_store_2_consta
>  }
>
>  ; GCN-LABEL: {{^}}merge_global_store_2_constants_f32_i32:
> -; GCN: buffer_store_dwordx2
> +; SI-DAG: s_mov_b32 [[SLO:s[0-9]+]], 4.0
> +; SI-DAG: s_movk_i32 [[SHI:s[0-9]+]], 0x7b{{$}}
> +; SI-DAG: v_mov_b32_e32 v[[VLO:[0-9]+]], [[SLO]]
> +; SI-DAG: v_mov_b32_e32 v[[VHI:[0-9]+]], [[SHI]]
> +; GCN: buffer_store_dwordx2 v{{\[}}[[VLO]]:[[VHI]]{{\]}}
>  define void @merge_global_store_2_constants_f32_i32(float addrspace(1)*
> %out) #0 {
>    %out.gep.1 = getelementptr float, float addrspace(1)* %out, i32 1
>    %out.gep.1.bc = bitcast float addrspace(1)* %out.gep.1 to i32
> addrspace(1)*
> @@ -99,7 +103,11 @@ define void @merge_global_store_2_consta
>  }
>
>  ; GCN-LABEL: {{^}}merge_global_store_4_constants_i32:
> -; GCN: buffer_store_dwordx4
> +; GCN-DAG: v_mov_b32_e32 v[[HI:[0-9]+]], 0x14d{{$}}
> +; GCN-DAG: v_mov_b32_e32 v{{[0-9]+}}, 0x1c8{{$}}
> +; GCN-DAG: v_mov_b32_e32 v{{[0-9]+}}, 0x7b{{$}}
> +; GCN-DAG: v_mov_b32_e32 v[[LO:[0-9]+]], 0x4d2{{$}}
> +; GCN: buffer_store_dwordx4 v{{\[}}[[LO]]:[[HI]]{{\]}}
>  define void @merge_global_store_4_constants_i32(i32 addrspace(1)* %out)
> #0 {
>    %out.gep.1 = getelementptr i32, i32 addrspace(1)* %out, i32 1
>    %out.gep.2 = getelementptr i32, i32 addrspace(1)* %out, i32 2
>
> Modified: llvm/trunk/test/CodeGen/X86/2012-11-28-merge-store-alias.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2012-11-28-merge-store-alias.ll?rev=239539&r1=239538&r2=239539&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/2012-11-28-merge-store-alias.ll (original)
> +++ llvm/trunk/test/CodeGen/X86/2012-11-28-merge-store-alias.ll Thu Jun 11
> 11:03:52 2015
> @@ -3,6 +3,7 @@
>  ; CHECK: merge_stores_can
>  ; CHECK: callq foo
>  ; CHECK: xorps %xmm0, %xmm0
> +; CHECK-NEXT: movl 36(%rsp), %ebp
>  ; CHECK-NEXT: movups  %xmm0
>  ; CHECK: callq foo
>  ; CHECK: ret
>
>
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