[llvm-commits] [llvm] r81173 - in /llvm/trunk: include/llvm/Analysis/ValueTracking.h lib/Analysis/ValueTracking.cpp

[Chris Lattner]

Author: lattner
Date: Mon Sep  7 19:06:16 2009
New Revision: 81173

URL: http://llvm.org/viewvc/llvm-project?rev=81173&view=rev
Log:
add some comments to describe the invariants.

Modified:
    llvm/trunk/include/llvm/Analysis/ValueTracking.h
    llvm/trunk/lib/Analysis/ValueTracking.cpp

Modified: llvm/trunk/include/llvm/Analysis/ValueTracking.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ValueTracking.h?rev=81173&r1=81172&r2=81173&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Analysis/ValueTracking.h (original)
+++ llvm/trunk/include/llvm/Analysis/ValueTracking.h Mon Sep  7 19:06:16 2009
@@ -29,6 +29,12 @@
   /// 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 @@
   /// 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);
 

Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=81173&r1=81172&r2=81173&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Mon Sep  7 19:06:16 2009
@@ -35,6 +35,12 @@
 /// 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 @@
 /// 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);