[llvm-commits] [llvm] r158951 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineCalls.cpp test/Transforms/InstCombine/invoke.ll

[Nuno Lopes]

Quoting Duncan Sands <baldrick at free.fr>:

> Hi Nuno,
>
>> instcombine:  disable optimization of 'invoke null/undef'. I'll  
>> move this functionality to SimplifyCFG (since we cannot make  
>> changes to the CFG here).
>> Fixes the crashes with the attached test case
>
> can you just set "nounwind" on the invoke?  (Not sure if that is possible -
> maybe for an invoke it can only be done on the callee?).  Then some other
> pass will magically take care of it.

Actually that code was doing a bit more than removing the invoke. It  
was inserting an undefined operation before 'invoke null/undef' so  
that the simplify CFG pass could then replace the invoke with  
unreachable. My idea was to move this logic (invoke null ->  
unreachable) into simplify CFG. Sounds reasonable?

Nuno


> Ciao, Duncan.
>
>>
>> Added:
>>      llvm/trunk/test/Transforms/InstCombine/invoke.ll
>> Modified:
>>      llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
>> URL:  
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=158951&r1=158950&r2=158951&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
>> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Thu  
>> Jun 21 18:52:14 2012
>> @@ -917,24 +917,24 @@
>>       }
>>
>>     if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
>> -    // This instruction is not reachable, just remove it.  We  
>> insert a store to
>> -    // undef so that we know that this code is not reachable,  
>> despite the fact
>> -    // that we can't modify the CFG here.
>> -    new StoreInst(ConstantInt::getTrue(Callee->getContext()),
>> -               UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
>> -                  CS.getInstruction());
>> -
>>       // If CS does not return void then replaceAllUsesWith undef.
>>       // This allows ValueHandlers and custom metadata to adjust itself.
>>       if (!CS.getInstruction()->getType()->isVoidTy())
>>         ReplaceInstUsesWith(*CS.getInstruction(),
>>                              
>> UndefValue::get(CS.getInstruction()->getType()));
>>
>> -    if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
>> -      // Don't break the CFG, insert a dummy cond branch.
>> -      BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
>> -                         ConstantInt::getTrue(Callee->getContext()), II);
>> +    if (isa<InvokeInst>(CS.getInstruction())) {
>> +      // Can't remove an invoke because we cannot change the CFG.
>> +      return 0;
>>       }
>> +
>> +    // This instruction is not reachable, just remove it.  We  
>> insert a store to
>> +    // undef so that we know that this code is not reachable,  
>> despite the fact
>> +    // that we can't modify the CFG here.
>> +    new StoreInst(ConstantInt::getTrue(Callee->getContext()),
>> +                   
>> UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
>> +                  CS.getInstruction());
>> +
>>       return EraseInstFromFunction(*CS.getInstruction());
>>     }
>>
>>
>> Added: llvm/trunk/test/Transforms/InstCombine/invoke.ll
>> URL:  
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/invoke.ll?rev=158951&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/InstCombine/invoke.ll (added)
>> +++ llvm/trunk/test/Transforms/InstCombine/invoke.ll Thu Jun 21  
>> 18:52:14 2012
>> @@ -0,0 +1,47 @@
>> +; RUN: opt<  %s -instcombine -S | FileCheck %s
>> +target datalayout =  
>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>> +
>> +declare i32 @__gxx_personality_v0(...)
>> +declare void @__cxa_call_unexpected(i8*)
>> +declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readonly
>> +
>> +
>> +; CHECK: @f1
>> +define i64 @f1() nounwind uwtable ssp {
>> +entry:
>> +; CHECK: nvoke noalias i8* undef()
>> +  %call = invoke noalias i8* undef()
>> +          to label %invoke.cont unwind label %lpad
>> +
>> +invoke.cont:
>> +; CHECK: ret i64 0
>> +  %0 = tail call i64 @llvm.objectsize.i64(i8* %call, i1 false)
>> +  ret i64 %0
>> +
>> +lpad:
>> +  %1 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)*  
>> @__gxx_personality_v0 to i8*)
>> +          filter [0 x i8*] zeroinitializer
>> +  %2 = extractvalue { i8*, i32 } %1, 0
>> +  tail call void @__cxa_call_unexpected(i8* %2) noreturn nounwind
>> +  unreachable
>> +}
>> +
>> +; CHECK: @f2
>> +define i64 @f2() nounwind uwtable ssp {
>> +entry:
>> +; CHECK: nvoke noalias i8* null()
>> +  %call = invoke noalias i8* null()
>> +          to label %invoke.cont unwind label %lpad
>> +
>> +invoke.cont:
>> +; CHECK: ret i64 0
>> +  %0 = tail call i64 @llvm.objectsize.i64(i8* %call, i1 false)
>> +  ret i64 %0
>> +
>> +lpad:
>> +  %1 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)*  
>> @__gxx_personality_v0 to i8*)
>> +          filter [0 x i8*] zeroinitializer
>> +  %2 = extractvalue { i8*, i32 } %1, 0
>> +  tail call void @__cxa_call_unexpected(i8* %2) noreturn nounwind
>> +  unreachable
>> +}
>>