diff options
author | Chris Lattner <sabre@nondot.org> | 2008-06-02 01:18:21 +0000 |
---|---|---|
committer | Chris Lattner <sabre@nondot.org> | 2008-06-02 01:18:21 +0000 |
commit | 173234a68fb6ece106e77da443d87f09d5906cb9 (patch) | |
tree | 6523427685b3a84009f8879f4e6bbfa3e9457d9c /include/llvm/Analysis/ValueTracking.h | |
parent | 009e4f760969e3530cc2641a9599e646a20580c2 (diff) | |
download | llvm-173234a68fb6ece106e77da443d87f09d5906cb9.tar.gz llvm-173234a68fb6ece106e77da443d87f09d5906cb9.tar.bz2 llvm-173234a68fb6ece106e77da443d87f09d5906cb9.tar.xz |
move ComputeMaskedBits, MaskedValueIsZero, and ComputeNumSignBits
out of instcombine into a new file in libanalysis. This also teaches
ComputeNumSignBits about the number of sign bits in a constantint.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51863 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'include/llvm/Analysis/ValueTracking.h')
-rw-r--r-- | include/llvm/Analysis/ValueTracking.h | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h new file mode 100644 index 0000000000..d07e8904e1 --- /dev/null +++ b/include/llvm/Analysis/ValueTracking.h @@ -0,0 +1,48 @@ +//===- 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 + +namespace llvm { + class Value; + 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); + + 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); + +} // end namespace llvm + +#endif |