[llvm] r310604 - [X86] Keep dependencies when constructing loads in combineStore
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 10 18:54:43 PDT 2017
Merged to 5.0 in r310678.
On Thu, Aug 10, 2017 at 8:12 AM, Nirav Dave via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: niravd
> Date: Thu Aug 10 08:12:32 2017
> New Revision: 310604
>
> URL: http://llvm.org/viewvc/llvm-project?rev=310604&view=rev
> Log:
> [X86] Keep dependencies when constructing loads in combineStore
>
> Summary:
> Preserve chain dependecies between old and new loads constructed to
> prevent loads from reordering below later stores.
>
> Fixes PR34088.
>
> Reviewers: craig.topper, spatel, RKSimon, efriedma
>
> Subscribers: llvm-commits
>
> Differential Revision: https://reviews.llvm.org/D36528
>
> Added:
> llvm/trunk/test/CodeGen/X86/pr34088.ll
> Modified:
> llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
> llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>
> Modified: llvm/trunk/include/llvm/CodeGen/SelectionDAG.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/SelectionDAG.h?rev=310604&r1=310603&r2=310604&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/CodeGen/SelectionDAG.h (original)
> +++ llvm/trunk/include/llvm/CodeGen/SelectionDAG.h Thu Aug 10 08:12:32 2017
> @@ -1222,8 +1222,9 @@ public:
> /// If an existing load has uses of its chain, create a token factor node with
> /// that chain and the new memory node's chain and update users of the old
> /// chain to the token factor. This ensures that the new memory node will have
> - /// the same relative memory dependency position as the old load.
> - void makeEquivalentMemoryOrdering(LoadSDNode *Old, SDValue New);
> + /// the same relative memory dependency position as the old load. Returns the
> + /// new merged load chain.
> + SDValue makeEquivalentMemoryOrdering(LoadSDNode *Old, SDValue New);
>
> /// Topological-sort the AllNodes list and a
> /// assign a unique node id for each node in the DAG based on their
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=310604&r1=310603&r2=310604&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Thu Aug 10 08:12:32 2017
> @@ -7339,22 +7339,23 @@ void SelectionDAG::TransferDbgValues(SDV
> AddDbgValue(I, ToNode, false);
> }
>
> -void SelectionDAG::makeEquivalentMemoryOrdering(LoadSDNode *OldLoad,
> - SDValue NewMemOp) {
> +SDValue SelectionDAG::makeEquivalentMemoryOrdering(LoadSDNode *OldLoad,
> + SDValue NewMemOp) {
> assert(isa<MemSDNode>(NewMemOp.getNode()) && "Expected a memop node");
> - if (!OldLoad->hasAnyUseOfValue(1))
> - return;
> -
> // The new memory operation must have the same position as the old load in
> // terms of memory dependency. Create a TokenFactor for the old load and new
> // memory operation and update uses of the old load's output chain to use that
> // TokenFactor.
> SDValue OldChain = SDValue(OldLoad, 1);
> SDValue NewChain = SDValue(NewMemOp.getNode(), 1);
> + if (!OldLoad->hasAnyUseOfValue(1))
> + return NewChain;
> +
> SDValue TokenFactor =
> getNode(ISD::TokenFactor, SDLoc(OldLoad), MVT::Other, OldChain, NewChain);
> ReplaceAllUsesOfValueWith(OldChain, TokenFactor);
> UpdateNodeOperands(TokenFactor.getNode(), OldChain, NewChain);
> + return TokenFactor;
> }
>
> //===----------------------------------------------------------------------===//
>
> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=310604&r1=310603&r2=310604&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu Aug 10 08:12:32 2017
> @@ -33349,7 +33349,8 @@ static SDValue combineStore(SDNode *N, S
> SDValue NewLd = DAG.getLoad(LdVT, LdDL, Ld->getChain(), Ld->getBasePtr(),
> Ld->getPointerInfo(), Ld->getAlignment(),
> Ld->getMemOperand()->getFlags());
> - SDValue NewChain = NewLd.getValue(1);
> + // Make sure new load is placed in same chain order.
> + SDValue NewChain = DAG.makeEquivalentMemoryOrdering(Ld, NewLd);
> if (TokenFactorIndex >= 0) {
> Ops.push_back(NewChain);
> NewChain = DAG.getNode(ISD::TokenFactor, LdDL, MVT::Other, Ops);
> @@ -33370,11 +33371,12 @@ static SDValue combineStore(SDNode *N, S
> Ld->getPointerInfo().getWithOffset(4),
> MinAlign(Ld->getAlignment(), 4),
> Ld->getMemOperand()->getFlags());
> + // Make sure new loads are placed in same chain order.
> + SDValue NewChain = DAG.makeEquivalentMemoryOrdering(Ld, LoLd);
> + NewChain = DAG.makeEquivalentMemoryOrdering(Ld, HiLd);
>
> - SDValue NewChain = LoLd.getValue(1);
> if (TokenFactorIndex >= 0) {
> - Ops.push_back(LoLd);
> - Ops.push_back(HiLd);
> + Ops.push_back(NewChain);
> NewChain = DAG.getNode(ISD::TokenFactor, LdDL, MVT::Other, Ops);
> }
>
>
> Added: llvm/trunk/test/CodeGen/X86/pr34088.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr34088.ll?rev=310604&view=auto
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/pr34088.ll (added)
> +++ llvm/trunk/test/CodeGen/X86/pr34088.ll Thu Aug 10 08:12:32 2017
> @@ -0,0 +1,46 @@
> +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
> +; RUN: llc < %s -mtriple=i686-unknown -mcpu=pentium4 | FileCheck %s
> +
> +%struct.Foo = type { i32, %struct.Bar }
> +%struct.Bar = type { i32, %struct.Buffer, i32 }
> +%struct.Buffer = type { i8*, i32 }
> +
> +; This test checks that the load of store %2 is not dropped.
> +;
> +define i32 @pr34088() local_unnamed_addr {
> +; CHECK-LABEL: pr34088:
> +; CHECK: # BB#0: # %entry
> +; CHECK-NEXT: pushl %ebp
> +; CHECK-NEXT: .Lcfi0:
> +; CHECK-NEXT: .cfi_def_cfa_offset 8
> +; CHECK-NEXT: .Lcfi1:
> +; CHECK-NEXT: .cfi_offset %ebp, -8
> +; CHECK-NEXT: movl %esp, %ebp
> +; CHECK-NEXT: .Lcfi2:
> +; CHECK-NEXT: .cfi_def_cfa_register %ebp
> +; CHECK-NEXT: andl $-16, %esp
> +; CHECK-NEXT: subl $32, %esp
> +; CHECK-NEXT: xorps %xmm0, %xmm0
> +; CHECK-NEXT: movaps {{.*#+}} xmm1 = [205,205,205,205,205,205,205,205,205,205,205,205,205,205,205,205]
> +; CHECK-NEXT: xorl %eax, %eax
> +; CHECK-NEXT: movaps %xmm0, (%esp)
> +; CHECK-NEXT: movsd {{.*#+}} xmm0 = mem[0],zero
> +; CHECK-NEXT: movaps %xmm1, (%esp)
> +; CHECK-NEXT: movl $-842150451, {{[0-9]+}}(%esp) # imm = 0xCDCDCDCD
> +; CHECK-NEXT: movsd %xmm0, {{[0-9]+}}(%esp)
> +; CHECK-NEXT: movl %ebp, %esp
> +; CHECK-NEXT: popl %ebp
> +; CHECK-NEXT: retl
> +entry:
> + %foo = alloca %struct.Foo, align 4
> + %0 = bitcast %struct.Foo* %foo to i8*
> + call void @llvm.memset.p0i8.i32(i8* nonnull %0, i8 0, i32 20, i32 4, i1 false)
> + %buffer1 = getelementptr inbounds %struct.Foo, %struct.Foo* %foo, i32 0, i32 1, i32 1
> + %1 = bitcast %struct.Buffer* %buffer1 to i64*
> + %2 = load i64, i64* %1, align 4
> + call void @llvm.memset.p0i8.i32(i8* nonnull %0, i8 -51, i32 20, i32 4, i1 false)
> + store i64 %2, i64* %1, align 4
> + ret i32 0
> +}
> +
> +declare void @llvm.memset.p0i8.i32(i8* nocapture writeonly, i8, i32, i32, i1)
>
>
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