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Recognize 16-bit bswaps by relaxing overconstrained pattern.

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This implements Transforms/InstCombine/bswap.ll:test[34].


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29087 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-07-10 20:25:24 +00:00
parent e5ff22e605
commit 6423d4c64a
1 changed files with 5 additions and 2 deletions
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7
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -2976,9 +2976,12 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
if (A == Op0 || B == Op0) // A | (A & ?) --> A
return ReplaceInstUsesWith(I, Op0);
// (A | B) | C and A | (B | C) -> bswap if possible.
// (A | B) | C and A | (B | C) -> bswap if possible.
// (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
if (match(Op0, m_Or(m_Value(), m_Value())) ||
match(Op1, m_Or(m_Value(), m_Value()))) {
match(Op1, m_Or(m_Value(), m_Value())) ||
(match(Op0, m_Shift(m_Value(), m_Value())) &&
match(Op1, m_Shift(m_Value(), m_Value())))) {
if (Instruction *BSwap = MatchBSwap(I))
return BSwap;
}