From b45eabcf82da2360b4243c820cd32b706f671c1a Mon Sep 17 00:00:00 2001 From: Craig Topper Date: Wed, 26 Apr 2017 16:39:58 +0000 Subject: [ValueTracking] Introduce a KnownBits struct to wrap the two APInts for computeKnownBits This patch introduces a new KnownBits struct that wraps the two APInt used by computeKnownBits. This allows us to treat them as more of a unit. Initially I've just altered the signatures of computeKnownBits and InstCombine's simplifyDemandedBits to pass a KnownBits reference instead of two separate APInt references. I'll do similar to the SelectionDAG version of computeKnownBits/simplifyDemandedBits as a separate patch. I've added a constructor that allows initializing both APInts to the same bit width with a starting value of 0. This reduces the repeated pattern of initializing both APInts. Once place default constructed the APInts so I added a default constructor for those cases. Going forward I would like to add more methods that will work on the pairs. For example trunc, zext, and sext occur on both APInts together in several places. We should probably add a clear method that can be used to clear both pieces. Maybe a method to check for conflicting information. A method to return (Zero|One) so we don't write it out everywhere. Maybe a method for (Zero|One).isAllOnesValue() to determine if all bits are known. I'm sure there are many other methods we can come up with. Differential Revision: https://reviews.llvm.org/D32376 llvm-svn: 301432 --- llvm/lib/Transforms/Scalar/GuardWidening.cpp | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'llvm/lib/Transforms/Scalar/GuardWidening.cpp') diff --git a/llvm/lib/Transforms/Scalar/GuardWidening.cpp b/llvm/lib/Transforms/Scalar/GuardWidening.cpp index 7019287954a..48eda09c463 100644 --- a/llvm/lib/Transforms/Scalar/GuardWidening.cpp +++ b/llvm/lib/Transforms/Scalar/GuardWidening.cpp @@ -51,6 +51,7 @@ #include "llvm/IR/IntrinsicInst.h" #include "llvm/IR/PatternMatch.h" #include "llvm/Support/Debug.h" +#include "llvm/Support/KnownBits.h" #include "llvm/Transforms/Scalar.h" using namespace llvm; @@ -537,9 +538,9 @@ bool GuardWideningImpl::parseRangeChecks( } else if (match(Check.getBase(), m_Or(m_Value(OpLHS), m_ConstantInt(OpRHS)))) { unsigned BitWidth = OpLHS->getType()->getScalarSizeInBits(); - APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); - computeKnownBits(OpLHS, KnownZero, KnownOne, DL); - if ((OpRHS->getValue() & KnownZero) == OpRHS->getValue()) { + KnownBits Known(BitWidth); + computeKnownBits(OpLHS, Known, DL); + if ((OpRHS->getValue() & Known.Zero) == OpRHS->getValue()) { Check.setBase(OpLHS); APInt NewOffset = Check.getOffsetValue() + OpRHS->getValue(); Check.setOffset(ConstantInt::get(Ctx, NewOffset)); -- cgit v1.2.3