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(A & sext(C)) | (B & ~sext(C) -> C ? A : B

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58351 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2008-10-28 22:38:57 +00:00
parent 2275105edb
commit b493b2774c
2 changed files with 39 additions and 0 deletions
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19
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -4337,6 +4337,25 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
return BinaryOperator::CreateAnd(V1, Or);
}
}
// (A & sext(C0)) | (B & ~sext(C0) -> C0 ? A : B
if (isa<SExtInst>(C) &&
cast<User>(C)->getOperand(0)->getType() == Type::Int1Ty) {
if (match(D, m_Not(m_Value(C))))
return SelectInst::Create(cast<User>(C)->getOperand(0), A, B);
// And commutes, try both ways.
if (match(B, m_Not(m_Value(C))))
return SelectInst::Create(cast<User>(C)->getOperand(0), A, D);
}
// Or commutes, try both ways.
if (isa<SExtInst>(D) &&
cast<User>(D)->getOperand(0)->getType() == Type::Int1Ty) {
if (match(C, m_Not(m_Value(D))))
return SelectInst::Create(cast<User>(D)->getOperand(0), A, B);
// And commutes, try both ways.
if (match(A, m_Not(m_Value(D))))
return SelectInst::Create(cast<User>(D)->getOperand(0), C, B);
}
}
// (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.

20
test/Transforms/InstCombine/logical-select.ll Normal file
View File

@ -0,0 +1,20 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep select | count 2
define i32 @foo(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
%e = icmp slt i32 %a, %b
%f = sext i1 %e to i32
%g = and i32 %c, %f
%h = xor i32 %f, -1
%i = and i32 %d, %h
%j = or i32 %g, %i
ret i32 %j
}
define i32 @bar(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
%e = icmp slt i32 %a, %b
%f = sext i1 %e to i32
%g = and i32 %c, %f
%h = xor i32 %f, -1
%i = and i32 %d, %h
%j = or i32 %i, %g
ret i32 %j
}