[llvm-commits] [llvm] r153452 - in /llvm/trunk: lib/Analysis/InstructionSimplify.cpp lib/Analysis/ValueTracking.cpp test/Transforms/InstSimplify/pr12251.ll

[Chris Lattner]

On Mar 26, 2012, at 11:07 AM, Chad Rosier wrote:

> Author: mcrosier
> Date: Mon Mar 26 13:07:14 2012
> New Revision: 153452
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=153452&view=rev
> Log:
> Revert r153423 as this is causing failures on our internal nightly testers.

Is it possible the test has undefined behavior?

-Chris

> 
> Original commit message:
> Use the new range metadata in computeMaskedBits and add a new optimization to
> instruction simplify that lets us remove an and when loading a boolean value.
> 
> Removed:
>    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=153452&r1=153451&r2=153452&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
> +++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Mon Mar 26 13:07:14 2012
> @@ -1370,21 +1370,6 @@
>       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=153452&r1=153451&r2=153452&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
> +++ llvm/trunk/lib/Analysis/ValueTracking.cpp Mon Mar 26 13:07:14 2012
> @@ -20,10 +20,8 @@
> #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"
> @@ -197,26 +195,6 @@
>     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
> @@ -337,10 +315,6 @@
>   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);
> 
> Removed: llvm/trunk/test/Transforms/InstSimplify/pr12251.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/pr12251.ll?rev=153451&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstSimplify/pr12251.ll (original)
> +++ llvm/trunk/test/Transforms/InstSimplify/pr12251.ll (removed)
> @@ -1,15 +0,0 @@
> -; 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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