[llvm-commits] [llvm] r153587 - in /llvm/trunk: lib/Analysis/InstructionSimplify.cpp lib/Analysis/ValueTracking.cpp test/Transforms/InstSimplify/pr12251.ll

[Chad Rosier]

Rafael,
Sorry to revert this yet again, but we're seeing rather large regressions on the internal nightly testers.  I'll contact you via PM to assist in reproducing the problem.

 Regards,
  Chad

On Mar 28, 2012, at 11:42 AM, Chad Rosier wrote:

> Author: mcrosier
> Date: Wed Mar 28 13:42:50 2012
> New Revision: 153587
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=153587&view=rev
> Log:
> Revert r153521 as it's causing large regressions on the nightly testers.
> Original commit message for r153521 (aka r153423):
> 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.
> 
> 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=153587&r1=153586&r2=153587&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
> +++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Wed Mar 28 13:42:50 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=153587&r1=153586&r2=153587&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
> +++ llvm/trunk/lib/Analysis/ValueTracking.cpp Wed Mar 28 13:42:50 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=153586&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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