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author | Chris Lattner <sabre@nondot.org> | 2001-12-13 00:43:03 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2001-12-13 00:43:03 +0000 |
commit | 9a49b210c1ae2c619ecd969b5ec17a68690928a9 (patch) | |
tree | d14ae9d5cecaa497dcd307278357681517c334a4 | |
parent | 82d18aa0e42a4858c2cb7c15934cc3e567432490 (diff) | |
download | external_llvm-9a49b210c1ae2c619ecd969b5ec17a68690928a9.zip external_llvm-9a49b210c1ae2c619ecd969b5ec17a68690928a9.tar.gz external_llvm-9a49b210c1ae2c619ecd969b5ec17a68690928a9.tar.bz2 |
Swap operands now preserves the semantics of the binary operator by changing
the opcode of the instruction if possible.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1444 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | include/llvm/InstrTypes.h | 12 | ||||
-rw-r--r-- | lib/VMCore/iOperators.cpp | 26 |
2 files changed, 34 insertions, 4 deletions
diff --git a/include/llvm/InstrTypes.h b/include/llvm/InstrTypes.h index 54aab32..3d834e9 100644 --- a/include/llvm/InstrTypes.h +++ b/include/llvm/InstrTypes.h @@ -127,10 +127,14 @@ public: virtual const char *getOpcodeName() const = 0; - // swapOperands - Exchange the two operands to this instruction - void swapOperands() { - swap(Operands[0], Operands[1]); - } + // swapOperands - Exchange the two operands to this instruction. + // This instruction is safe to use on any binary instruction and + // does not modify the semantics of the instruction. If the + // instruction is order dependant (SetLT f.e.) the opcode is + // changed. If the instruction cannot be reversed (ie, it's a Div), + // then return true. + // + bool swapOperands(); // Methods for support type inquiry through isa, cast, and dyn_cast: static inline bool classof(const BinaryOperator *) { return true; } diff --git a/lib/VMCore/iOperators.cpp b/lib/VMCore/iOperators.cpp index 22b6052..cb53d5e 100644 --- a/lib/VMCore/iOperators.cpp +++ b/lib/VMCore/iOperators.cpp @@ -53,6 +53,32 @@ BinaryOperator *BinaryOperator::create(BinaryOps Op, Value *S1, Value *S2, } } +// swapOperands - Exchange the two operands to this instruction. This +// instruction is safe to use on any binary instruction and does not +// modify the semantics of the instruction. If the instruction is +// order dependant (SetLT f.e.) the opcode is changed. +// +bool BinaryOperator::swapOperands() { + switch (getOpcode()) { + // Instructions that don't need opcode modification + case Add: case Mul: + case And: case Xor: + case Or: + case SetEQ: case SetNE: + break; + // Instructions that need opcode modification + case SetGT: iType = SetLT; break; + case SetLT: iType = SetGT; break; + case SetGE: iType = SetLE; break; + case SetLE: iType = SetGE; break; + // Error on the side of caution + default: + return true; + } + swap(Operands[0], Operands[1]); + return false; +} + //===----------------------------------------------------------------------===// // GenericBinaryInst Class |