[llvm-commits] [llvm] r91820 - in /llvm/trunk: lib/Transforms/Utils/SSAUpdater.cpp test/Transforms/LoopRotate/phi-duplicate.ll

[Chris Lattner]

On Dec 21, 2009, at 10:44 AM, Evan Cheng wrote:
> Machine SSAUpdate already checks for duplicate phi's.

Ah, thanks!

-Chris

> Evan
> 
> On Dec 20, 2009, at 11:16 PM, Chris Lattner wrote:
> 
>> Author: lattner
>> Date: Mon Dec 21 01:16:11 2009
>> New Revision: 91820
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=91820&view=rev
>> Log:
>> fix PR5837 by having SSAUpdate reuse phi nodes for the
>> 'GetValueInMiddleOfBlock' case, instead of inserting 
>> duplicates.
>> 
>> A similar fix is almost certainly needed by the machine-level
>> SSAUpdate implementation.
>> 
>> Added:
>>   llvm/trunk/test/Transforms/LoopRotate/phi-duplicate.ll
>> Modified:
>>   llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp
>> 
>> Modified: llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp?rev=91820&r1=91819&r2=91820&view=diff
>> 
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Utils/SSAUpdater.cpp Mon Dec 21 01:16:11 2009
>> @@ -149,7 +149,29 @@
>>  if (SingularValue != 0)
>>    return SingularValue;
>> 
>> -  // Otherwise, we do need a PHI: insert one now.
>> +  // Otherwise, we do need a PHI: check to see if we already have one available
>> +  // in this block that produces the right value.
>> +  if (isa<PHINode>(BB->begin())) {
>> +    DenseMap<BasicBlock*, Value*> ValueMapping(PredValues.begin(),
>> +                                               PredValues.end());
>> +    PHINode *SomePHI;
>> +    for (BasicBlock::iterator It = BB->begin();
>> +         (SomePHI = dyn_cast<PHINode>(It)); ++It) {
>> +      // Scan this phi to see if it is what we need.
>> +      bool Equal = true;
>> +      for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i)
>> +        if (ValueMapping[SomePHI->getIncomingBlock(i)] !=
>> +            SomePHI->getIncomingValue(i)) {
>> +          Equal = false;
>> +          break;
>> +        }
>> +         
>> +      if (Equal)
>> +        return SomePHI;
>> +    }
>> +  }
>> +  
>> +  // Ok, we have no way out, insert a new one now.
>>  PHINode *InsertedPHI = PHINode::Create(PrototypeValue->getType(),
>>                                         PrototypeValue->getName(),
>>                                         &BB->front());
>> 
>> Added: llvm/trunk/test/Transforms/LoopRotate/phi-duplicate.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopRotate/phi-duplicate.ll?rev=91820&view=auto
>> 
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/LoopRotate/phi-duplicate.ll (added)
>> +++ llvm/trunk/test/Transforms/LoopRotate/phi-duplicate.ll Mon Dec 21 01:16:11 2009
>> @@ -0,0 +1,35 @@
>> +; RUN: opt -S %s -loop-rotate | 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"
>> +target triple = "x86_64-apple-darwin10.0"
>> +
>> +; PR5837
>> +define void @test(i32 %N, double* %G) nounwind ssp {
>> +entry:
>> +  br label %for.cond
>> +
>> +for.cond:                                         ; preds = %for.body, %entry
>> +  %j.0 = phi i64 [ 1, %entry ], [ %inc, %for.body ] ; <i64> [#uses=5]
>> +  %cmp = icmp slt i64 %j.0, 1000                  ; <i1> [#uses=1]
>> +  br i1 %cmp, label %for.body, label %for.end
>> +
>> +for.body:                                         ; preds = %for.cond
>> +  %arrayidx = getelementptr inbounds double* %G, i64 %j.0 ; <double*> [#uses=1]
>> +  %tmp3 = load double* %arrayidx                  ; <double> [#uses=1]
>> +  %sub = sub i64 %j.0, 1                          ; <i64> [#uses=1]
>> +  %arrayidx6 = getelementptr inbounds double* %G, i64 %sub ; <double*> [#uses=1]
>> +  %tmp7 = load double* %arrayidx6                 ; <double> [#uses=1]
>> +  %add = fadd double %tmp3, %tmp7                 ; <double> [#uses=1]
>> +  %arrayidx10 = getelementptr inbounds double* %G, i64 %j.0 ; <double*> [#uses=1]
>> +  store double %add, double* %arrayidx10
>> +  %inc = add nsw i64 %j.0, 1                      ; <i64> [#uses=1]
>> +  br label %for.cond
>> +
>> +for.end:                                          ; preds = %for.cond
>> +  ret void
>> +}
>> +; Should only end up with one phi.
>> +; CHECK: for.body:
>> +; CHECK-NEXT: %j.02 = phi i64
>> +; CHECK-NOT phi
>> +; CHECK: ret void
>> +
>> 
>> 
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