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

[Evan Cheng]

Machine SSAUpdate already checks for duplicate phi's.

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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