From cf5128ec01f45d2bf7eadc20b253cb44486e473f Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 8 Sep 2009 00:06:16 +0000 Subject: [PATCH] add some comments to describe the invariants. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81173 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/ValueTracking.h | 12 ++++++++++++ lib/Analysis/ValueTracking.cpp | 12 ++++++++++++ 2 files changed, 24 insertions(+) diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h index 6bb3b3c98e8..212b5d1da5f 100644 --- a/include/llvm/Analysis/ValueTracking.h +++ b/include/llvm/Analysis/ValueTracking.h @@ -29,6 +29,12 @@ namespace llvm { /// 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 /// processing. + /// + /// This function is defined on values with integer type, values with pointer + /// type (but only if TD is non-null), and vectors of integers. In the case + /// where V is a vector, the mask, known zero, and known one values are the + /// same width as the vector element, and the bit is set only if it is true + /// for all of the elements in the vector. void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero, APInt &KnownOne, const TargetData *TD = 0, unsigned Depth = 0); @@ -36,6 +42,12 @@ namespace llvm { /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use /// this predicate to simplify operations downstream. Mask is known to be /// zero for bits that V cannot have. + /// + /// This function is defined on values with integer type, values with pointer + /// type (but only if TD is non-null), and vectors of integers. In the case + /// where V is a vector, the mask, known zero, and known one values are the + /// same width as the vector element, and the bit is set only if it is true + /// for all of the elements in the vector. bool MaskedValueIsZero(Value *V, const APInt &Mask, const TargetData *TD = 0, unsigned Depth = 0); diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index aa71f1dc678..78bb3dbc65d 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -35,6 +35,12 @@ using namespace llvm; /// optimized based on the contradictory assumption that it is non-zero. /// Because instcombine aggressively folds operations with undef args anyway, /// this won't lose us code quality. +/// +/// This function is defined on values with integer type, values with pointer +/// type (but only if TD is non-null), and vectors of integers. In the case +/// where V is a vector, the mask, known zero, and known one values are the +/// same width as the vector element, and the bit is set only if it is true +/// for all of the elements in the vector. void llvm::ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero, APInt &KnownOne, const TargetData *TD, unsigned Depth) { @@ -608,6 +614,12 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask, /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use /// this predicate to simplify operations downstream. Mask is known to be zero /// for bits that V cannot have. +/// +/// This function is defined on values with integer type, values with pointer +/// type (but only if TD is non-null), and vectors of integers. In the case +/// where V is a vector, the mask, known zero, and known one values are the +/// same width as the vector element, and the bit is set only if it is true +/// for all of the elements in the vector. bool llvm::MaskedValueIsZero(Value *V, const APInt &Mask, const TargetData *TD, unsigned Depth) { APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0); -- 2.34.1