[llvm] r176154 - SelectionDAG: If llvm.donothing has a landingpad, we should clear

[Duncan Sands]

Hi Manman,

On 27/02/13 03:11, Manman Ren wrote:
> Author: mren
> Date: Tue Feb 26 20:11:57 2013
> New Revision: 176154
>
> URL: http://llvm.org/viewvc/llvm-project?rev=176154&view=rev
> Log:
> SelectionDAG: If llvm.donothing has a landingpad, we should clear
> CurrentCallSite to avoid an assertion failure:
> assert(MMI.getCurrentCallSite() == 0 && "Overlapping call sites!");
>

why is that assertion firing and what does it mean exactly?  I'm worried
that you might be papering over the real problem.

Ciao, Duncan.

> rdar://problem/13228754
>
> Added:
>      llvm/trunk/test/CodeGen/ARM/invoke-donothing-assert.ll
> Modified:
>      llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=176154&r1=176153&r2=176154&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Tue Feb 26 20:11:57 2013
> @@ -1872,6 +1872,13 @@ void SelectionDAGBuilder::visitInvoke(co
>       visitInlineAsm(&I);
>     else if (Fn && Fn->isIntrinsic()) {
>       assert(Fn->getIntrinsicID() == Intrinsic::donothing);
> +    // If donothing has a landingpad, we should clear CurrentCallSite.
> +    if (LandingPad) {
> +      MachineModuleInfo &MMI = DAG.getMachineFunction().getMMI();
> +      unsigned CallSiteIndex = MMI.getCurrentCallSite();
> +      if (CallSiteIndex)
> +        MMI.setCurrentCallSite(0);
> +    }
>       // Ignore invokes to @llvm.donothing: jump directly to the next BB.
>     } else
>       LowerCallTo(&I, getValue(Callee), false, LandingPad);
>
> Added: llvm/trunk/test/CodeGen/ARM/invoke-donothing-assert.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/invoke-donothing-assert.ll?rev=176154&view=auto
> ==============================================================================
> --- llvm/trunk/test/CodeGen/ARM/invoke-donothing-assert.ll (added)
> +++ llvm/trunk/test/CodeGen/ARM/invoke-donothing-assert.ll Tue Feb 26 20:11:57 2013
> @@ -0,0 +1,40 @@
> +; RUN: llc < %s -mtriple=armv7-apple-ios | FileCheck %s
> +; This testcase makes sure we can handle invoke @llvm.donothing without
> +; assertion failure.
> +; rdar://problem/13228754
> +; CHECK: .globl  _main
> +
> +declare void @callA()
> +declare i32 @__gxx_personality_sj0(...)
> +
> +define void @main() {
> +invoke.cont:
> +  invoke void @callA()
> +          to label %invoke.cont25 unwind label %lpad2
> +invoke.cont25:
> +  invoke void @llvm.donothing()
> +          to label %invoke.cont27 unwind label %lpad15
> +
> +invoke.cont27:
> +  invoke void @callB()
> +          to label %invoke.cont75 unwind label %lpad15
> +
> +invoke.cont75:
> +  ret void
> +
> +lpad2:
> +  %0 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*)
> +          cleanup
> +  br label %eh.resume
> +
> +lpad15:
> +  %1 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*)
> +          cleanup
> +  br label %eh.resume
> +
> +eh.resume:
> +  resume { i8*, i32 } zeroinitializer
> +}
> +
> +declare void @callB()
> +declare void @llvm.donothing() nounwind readnone
>
>
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