[llvm-commits] [llvm] r153423 - in /llvm/trunk: lib/Analysis/InstructionSimplify.cpp lib/Analysis/ValueTracking.cpp test/Transforms/InstSimplify/pr12251.ll

[Chad Rosier]

Hi Rafael,
This commit is causing an execution-time failure for the MultiSource/Benchmarks/FreeBench/distray/distray benchmark on all of our ARM nightly testers.  Would you mind investigating?

 Regards,
  Chad

On Mar 25, 2012, at 6:44 PM, Rafael Espindola <rafael.espindola at gmail.com> wrote:

> Author: rafael
> Date: Sun Mar 25 20:44:11 2012
> New Revision: 153423
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=153423&view=rev
> Log:
> Use the new range metadata in computeMaskedBits and add a new optimization to
> instruction simplify that lets us remove an and when loding a boolean value.
> 
> Added:
>    llvm/trunk/test/Transforms/InstSimplify/pr12251.ll
> Modified:
>    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
>    llvm/trunk/lib/Analysis/ValueTracking.cpp
> 
> Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=153423&r1=153422&r2=153423&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
> +++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Sun Mar 25 20:44:11 2012
> @@ -1370,6 +1370,21 @@
>       return Op1;
>   }
> 
> +  unsigned Bitwidth = Op1->getType()->getScalarSizeInBits();
> +  APInt DemandedMask = APInt::getAllOnesValue(Bitwidth);
> +  APInt KnownZero0 = APInt::getNullValue(Bitwidth);
> +  APInt KnownOne0 = APInt::getNullValue(Bitwidth);
> +  ComputeMaskedBits(Op0, DemandedMask, KnownZero0, KnownOne0);
> +  APInt KnownZero1 = APInt::getNullValue(Bitwidth);
> +  APInt KnownOne1 = APInt::getNullValue(Bitwidth);
> +  ComputeMaskedBits(Op1, DemandedMask, KnownZero1, KnownOne1);
> +
> +  if ((KnownZero0 | KnownOne1).isAllOnesValue())
> +    return Op0;
> +
> +  if ((KnownZero1 | KnownOne0).isAllOnesValue())
> +    return Op1;
> +
>   // Try some generic simplifications for associative operations.
>   if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
>                                           MaxRecurse))
> 
> Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=153423&r1=153422&r2=153423&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
> +++ llvm/trunk/lib/Analysis/ValueTracking.cpp Sun Mar 25 20:44:11 2012
> @@ -20,8 +20,10 @@
> #include "llvm/GlobalAlias.h"
> #include "llvm/IntrinsicInst.h"
> #include "llvm/LLVMContext.h"
> +#include "llvm/Metadata.h"
> #include "llvm/Operator.h"
> #include "llvm/Target/TargetData.h"
> +#include "llvm/Support/ConstantRange.h"
> #include "llvm/Support/GetElementPtrTypeIterator.h"
> #include "llvm/Support/MathExtras.h"
> #include "llvm/Support/PatternMatch.h"
> @@ -195,6 +197,26 @@
>     KnownOne.setBit(BitWidth - 1);
> }
> 
> +static void computeMaskedBitsLoad(const MDNode &Ranges, const APInt &Mask,
> +                                  APInt &KnownZero) {
> +  unsigned BitWidth = Mask.getBitWidth();
> +  unsigned NumRanges = Ranges.getNumOperands() / 2;
> +  assert(NumRanges >= 1);
> +
> +  // Use the high end of the ranges to find leading zeros.
> +  unsigned MinLeadingZeros = BitWidth;
> +  for (unsigned i = 0; i < NumRanges; ++i) {
> +    ConstantInt *Lower = cast<ConstantInt>(Ranges.getOperand(2*i + 0));
> +    ConstantInt *Upper = cast<ConstantInt>(Ranges.getOperand(2*i + 1));
> +    ConstantRange Range(Lower->getValue(), Upper->getValue());
> +    if (Range.isWrappedSet())
> +      MinLeadingZeros = 0; // -1 has no zeros
> +    unsigned LeadingZeros = (Upper->getValue() - 1).countLeadingZeros();
> +    MinLeadingZeros = std::min(LeadingZeros, MinLeadingZeros);
> +  }
> +
> +  KnownZero = Mask & APInt::getHighBitsSet(BitWidth, MinLeadingZeros);
> +}
> /// ComputeMaskedBits - Determine which of the bits specified in Mask are
> /// known to be either zero or one and return them in the KnownZero/KnownOne
> /// bit sets.  This code only analyzes bits in Mask, in order to short-circuit
> @@ -315,6 +337,10 @@
>   APInt KnownZero2(KnownZero), KnownOne2(KnownOne);
>   switch (I->getOpcode()) {
>   default: break;
> +  case Instruction::Load:
> +    if (MDNode *MD = cast<LoadInst>(I)->getMetadata(LLVMContext::MD_range))
> +      computeMaskedBitsLoad(*MD, Mask, KnownZero);
> +    return;
>   case Instruction::And: {
>     // If either the LHS or the RHS are Zero, the result is zero.
>     ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, TD, Depth+1);
> 
> Added: llvm/trunk/test/Transforms/InstSimplify/pr12251.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/pr12251.ll?rev=153423&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstSimplify/pr12251.ll (added)
> +++ llvm/trunk/test/Transforms/InstSimplify/pr12251.ll Sun Mar 25 20:44:11 2012
> @@ -0,0 +1,15 @@
> +; RUN: opt < %s -instsimplify -S | FileCheck %s
> +
> +define zeroext i1 @_Z3fooPb(i8* nocapture %x) {
> +entry:
> +  %a = load i8* %x, align 1, !range !0
> +  %b = and i8 %a, 1
> +  %tobool = icmp ne i8 %b, 0
> +  ret i1 %tobool
> +}
> +
> +; CHECK: %a = load i8* %x, align 1, !range !0
> +; CHECK-NEXT: %tobool = icmp ne i8 %a, 0
> +; CHECK-NEXT: ret i1 %tobool
> +
> +!0 = metadata !{i8 0, i8 2}
> 
> 
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