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author | Pete Cooper <peter_cooper@apple.com> | 2011-12-17 01:20:32 +0000 |
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committer | Pete Cooper <peter_cooper@apple.com> | 2011-12-17 01:20:32 +0000 |
commit | 2e33944c101f2a08ed1d85e807830f2fc089dd06 (patch) | |
tree | 0b7d59d60a8c61d5068358f571c3532bc25b27ad /include/llvm/Transforms | |
parent | 8f7d12ccfd8feb258bdf4e582592bc00beacc7c6 (diff) | |
download | external_llvm-2e33944c101f2a08ed1d85e807830f2fc089dd06.zip external_llvm-2e33944c101f2a08ed1d85e807830f2fc089dd06.tar.gz external_llvm-2e33944c101f2a08ed1d85e807830f2fc089dd06.tar.bz2 |
Refactor code used in InstCombine::FoldAndOfICmps to new file.
This will be used by SimplifyCfg in a later commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146803 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'include/llvm/Transforms')
-rw-r--r-- | include/llvm/Transforms/Utils/CmpInstAnalysis.h | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/include/llvm/Transforms/Utils/CmpInstAnalysis.h b/include/llvm/Transforms/Utils/CmpInstAnalysis.h new file mode 100644 index 0000000..7ad7bdd --- /dev/null +++ b/include/llvm/Transforms/Utils/CmpInstAnalysis.h @@ -0,0 +1,66 @@ +//===-- CmpInstAnalysis.h - Utils to help fold compare insts ------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file holds routines to help analyse compare instructions +// and fold them into constants or other compare instructions +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H +#define LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H + +#include "llvm/InstrTypes.h" + +namespace llvm { + class ICmpInst; + class Value; + + /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits + /// are carefully arranged to allow folding of expressions such as: + /// + /// (A < B) | (A > B) --> (A != B) + /// + /// Note that this is only valid if the first and second predicates have the + /// same sign. Is illegal to do: (A u< B) | (A s> B) + /// + /// Three bits are used to represent the condition, as follows: + /// 0 A > B + /// 1 A == B + /// 2 A < B + /// + /// <=> Value Definition + /// 000 0 Always false + /// 001 1 A > B + /// 010 2 A == B + /// 011 3 A >= B + /// 100 4 A < B + /// 101 5 A != B + /// 110 6 A <= B + /// 111 7 Always true + /// + unsigned getICmpCode(const ICmpInst *ICI, bool InvertPred = false); + + /// getICmpValue - This is the complement of getICmpCode, which turns an + /// opcode and two operands into either a constant true or false, or the + /// predicate for a new ICmp instruction. The sign is passed in to determine + /// which kind of predicate to use in the new icmp instruction. + /// Non-NULL return value will be a true or false constant. + /// NULL return means a new ICmp is needed. The predicate for which is + /// output in NewICmpPred. + Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS, + CmpInst::Predicate &NewICmpPred); + + /// PredicatesFoldable - Return true if both predicates match sign or if at + /// least one of them is an equality comparison (which is signless). + bool PredicatesFoldable(CmpInst::Predicate p1, CmpInst::Predicate p2); + +} // end namespace llvm + +#endif + |