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Implement or.ll:test21. This teaches instcombine to be able to turn this:

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struct {
   unsigned int bit0:1;
   unsigned int ubyte:31;
} sdata;

void foo() {
  sdata.ubyte++;
}

into this:

foo:
        add DWORD PTR [sdata], 2
        ret

instead of this:

foo:
        mov %EAX, DWORD PTR [sdata]
        mov %ECX, %EAX
        add %ECX, 2
        and %ECX, -2
        and %EAX, 1
        or %EAX, %ECX
        mov DWORD PTR [sdata], %EAX
        ret

llvm-svn: 23376
This commit is contained in:
Chris Lattner 2005-09-18 03:42:07 +00:00
parent c6c62e7864
commit 1466ade38b
1 changed files with 25 additions and 3 deletions
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28
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1921,10 +1921,31 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
}
// (A & C1)|(A & C2) == A & (C1|C2)
// (A & C1)|(B & C2)
if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
// if A == (add B, C3) or B == (add A, C4)
ConstantInt *C3 = 0;
Value *V = 0;
if ((match(A, m_Add(m_Value(V), m_ConstantInt(C3))) && V == B ||
match(B, m_Add(m_Value(V), m_ConstantInt(C3))) && V == A)) {
if (V == A) std::swap(C1, C2);
// We have: ((V + C3) & C1) | (V & C2)
// if C2 = ~C1 and (C3 & C2) == 0 and C2 is 0+1+
if (C1 == ConstantExpr::getNot(C2) &&
ConstantExpr::getAnd(C3, C2)->isNullValue() &&
(C2->getRawValue() & (C2->getRawValue()+1)) == 0) {
// Return V+C3.
std::cerr << "Simpl: " << *A << "Simpl2: " << *B << "Simpl3: " << I;
return ReplaceInstUsesWith(I, V == A ? B : A);
}
}
}
if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
if (A == Op1) // ~A | A == -1
@ -2040,6 +2061,7 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
}
}
}
return Changed ? &I : 0;
}