Import LLVM, at r72732.vendor/llvm/llvm-r72732

1 files changed, 87 insertions, 0 deletions

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
new file mode 100644
index 000000000000..5f5f77a5c9fe
--- /dev/null
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -0,0 +1,87 @@
+//===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains routines that help analyze properties that chains of
+// computations have.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_VALUETRACKING_H
+#define LLVM_ANALYSIS_VALUETRACKING_H
+
+#include "llvm/Support/DataTypes.h"
+#include <string>
+
+namespace llvm {
+  class Value;
+  class Instruction;
+  class APInt;
+  class TargetData;
+  
+  /// 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
+  /// processing.
+  void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
+                         APInt &KnownOne, TargetData *TD = 0,
+                         unsigned Depth = 0);
+  
+  /// 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.
+  bool MaskedValueIsZero(Value *V, const APInt &Mask, 
+                         TargetData *TD = 0, unsigned Depth = 0);
+
+  
+  /// ComputeNumSignBits - Return the number of times the sign bit of the
+  /// register is replicated into the other bits.  We know that at least 1 bit
+  /// is always equal to the sign bit (itself), but other cases can give us
+  /// information.  For example, immediately after an "ashr X, 2", we know that
+  /// the top 3 bits are all equal to each other, so we return 3.
+  ///
+  /// 'Op' must have a scalar integer type.
+  ///
+  unsigned ComputeNumSignBits(Value *Op, TargetData *TD = 0,
+                              unsigned Depth = 0);
+
+  /// CannotBeNegativeZero - Return true if we can prove that the specified FP 
+  /// value is never equal to -0.0.
+  ///
+  bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
+
+  /// FindScalarValue - Given an aggregrate and an sequence of indices, see if
+  /// the scalar value indexed is already around as a register, for example if
+  /// it were inserted directly into the aggregrate.
+  ///
+  /// If InsertBefore is not null, this function will duplicate (modified)
+  /// insertvalues when a part of a nested struct is extracted.
+  Value *FindInsertedValue(Value *V,
+                           const unsigned *idx_begin,
+                           const unsigned *idx_end,
+                           Instruction *InsertBefore = 0);
+
+  /// This is a convenience wrapper for finding values indexed by a single index
+  /// only.
+  inline Value *FindInsertedValue(Value *V, const unsigned Idx,
+                                  Instruction *InsertBefore = 0) {
+    const unsigned Idxs[1] = { Idx };
+    return FindInsertedValue(V, &Idxs[0], &Idxs[1], InsertBefore);
+  }
+  
+  /// GetConstantStringInfo - This function computes the length of a
+  /// null-terminated C string pointed to by V.  If successful, it returns true
+  /// and returns the string in Str.  If unsuccessful, it returns false.  If
+  /// StopAtNul is set to true (the default), the returned string is truncated
+  /// by a nul character in the global.  If StopAtNul is false, the nul
+  /// character is included in the result string.
+  bool GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset = 0,
+                             bool StopAtNul = true);
+} // end namespace llvm
+
+#endif