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/Utils/BypassSlowDivision.cpp | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'llvm/lib/Transforms/Utils/BypassSlowDivision.cpp') diff --git a/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp b/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp index 1cfe3bd5364..7ffdad597a9 100644 --- a/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp +++ b/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp @@ -22,6 +22,7 @@ #include "llvm/IR/Function.h" #include "llvm/IR/IRBuilder.h" #include "llvm/IR/Instructions.h" +#include "llvm/Support/KnownBits.h" #include "llvm/Transforms/Utils/Local.h" using namespace llvm; @@ -256,14 +257,14 @@ ValueRange FastDivInsertionTask::getValueRange(Value *V, unsigned HiBits = LongLen - ShortLen; const DataLayout &DL = SlowDivOrRem->getModule()->getDataLayout(); - APInt Zeros(LongLen, 0), Ones(LongLen, 0); + KnownBits Known(LongLen); - computeKnownBits(V, Zeros, Ones, DL); + computeKnownBits(V, Known, DL); - if (Zeros.countLeadingOnes() >= HiBits) + if (Known.Zero.countLeadingOnes() >= HiBits) return VALRNG_KNOWN_SHORT; - if (Ones.countLeadingZeros() < HiBits) + if (Known.One.countLeadingZeros() < HiBits) return VALRNG_LIKELY_LONG; // Long integer divisions are often used in hashtable implementations. It's -- cgit v1.2.3