[llvm-commits] [llvm] r156896 - in /llvm/trunk: lib/Target/X86/X86ISelDAGToDAG.cpp test/CodeGen/X86/rd-mod-wr-eflags.ll

[Evan Cheng]

That would be PR12565.

Evan

On May 15, 2012, at 6:54 PM, Evan Cheng wrote:

> Author: evancheng
> Date: Tue May 15 20:54:27 2012
> New Revision: 156896
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=156896&view=rev
> Log:
> Avoid creating a cycle when folding load / op with flag / store. PR11451474. rdar://11451474
> 
> Modified:
>    llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
>    llvm/trunk/test/CodeGen/X86/rd-mod-wr-eflags.ll
> 
> Modified: llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp?rev=156896&r1=156895&r2=156896&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp Tue May 15 20:54:27 2012
> @@ -1905,6 +1905,20 @@
>         ChainCheck = true;
>         continue;
>       }
> +
> +      // Make sure using Op as part of the chain would not cause a cycle here.
> +      // In theory, we could check whether the chain node is a predecessor of
> +      // the load. But that can be very expensive. Instead visit the uses and
> +      // make sure they all have smaller node id than the load.
> +      int LoadId = LoadNode->getNodeId();
> +      for (SDNode::use_iterator UI = Op.getNode()->use_begin(),
> +             UE = UI->use_end(); UI != UE; ++UI) {
> +        if (UI.getUse().getResNo() != 0)
> +          continue;
> +        if (UI->getNodeId() > LoadId)
> +          return false;
> +      }
> +
>       ChainOps.push_back(Op);
>     }
> 
> 
> Modified: llvm/trunk/test/CodeGen/X86/rd-mod-wr-eflags.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/rd-mod-wr-eflags.ll?rev=156896&r1=156895&r2=156896&view=diff
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/rd-mod-wr-eflags.ll (original)
> +++ llvm/trunk/test/CodeGen/X86/rd-mod-wr-eflags.ll Tue May 15 20:54:27 2012
> @@ -177,3 +177,49 @@
> return:
>   ret void
> }
> +
> +; Deal with TokenFactor chain
> +; rdar://11236106
> + at foo = external global i64*, align 8
> +
> +define void @test3() nounwind ssp {
> +entry:
> +; CHECK: test3:
> +; CHECK: decq 16(%rax)
> +  %0 = load i64** @foo, align 8
> +  %arrayidx = getelementptr inbounds i64* %0, i64 2
> +  %1 = load i64* %arrayidx, align 8
> +  %dec = add i64 %1, -1
> +  store i64 %dec, i64* %arrayidx, align 8
> +  %cmp = icmp eq i64 %dec, 0
> +  br i1 %cmp, label %if.then, label %if.end
> +
> +if.then:
> +  tail call void @baz() nounwind
> +  br label %if.end
> +
> +if.end:
> +  ret void
> +}
> +
> +declare void @baz()
> +
> +; Avoid creating a cycle in the DAG which would trigger an assert in the
> +; scheduler.
> +; PR12565
> +; rdar://11451474
> + at x = external global i32, align 4
> + at y = external global i32, align 4
> + at z = external global i32, align 4
> +
> +define void @test4() nounwind uwtable ssp {
> +entry:
> +  %0 = load i32* @x, align 4
> +  %1 = load i32* @y, align 4
> +  %dec = add nsw i32 %1, -1
> +  store i32 %dec, i32* @y, align 4
> +  %tobool.i = icmp ne i32 %dec, 0
> +  %cond.i = select i1 %tobool.i, i32 %0, i32 0
> +  store i32 %cond.i, i32* @z, align 4
> +  ret void
> +}
> 
> 
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