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Generalize this transform, using MaskedValueIsZero, allowing us to compile:
struct S { unsigned int i : 6, j : 11, k : 15; } b; void plus3 (unsigned int x) { b.k += x; } To: plus3: mov %EAX, DWORD PTR [%ESP + 4] shl %EAX, 17 add DWORD PTR [b], %EAX ret instead of: plus3: mov %EAX, DWORD PTR [%ESP + 4] shl %EAX, 17 mov %ECX, DWORD PTR [b] add %EAX, %ECX and %EAX, -131072 and %ECX, 131071 or %ECX, %EAX mov DWORD PTR [b], %ECX ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23384 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -225,7 +225,6 @@ namespace {
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Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
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bool isSub, Instruction &I);
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Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
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bool Inside, Instruction &IB);
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};
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@ -1995,19 +1994,27 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
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return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
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// if A == (add B, C3) or B == (add A, C4)
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ConstantInt *C3 = 0;
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Value *V = 0;
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if ((match(A, m_Add(m_Value(V), m_ConstantInt(C3))) && V == B ||
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match(B, m_Add(m_Value(V), m_ConstantInt(C3))) && V == A)) {
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if (V == A) std::swap(C1, C2);
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// We have: ((V + C3) & C1) | (V & C2)
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// if C2 = ~C1 and (C3 & C2) == 0 and C2 is 0+1+
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if (C1 == ConstantExpr::getNot(C2) &&
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ConstantExpr::getAnd(C3, C2)->isNullValue() &&
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(C2->getRawValue() & (C2->getRawValue()+1)) == 0) {
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// Return V+C3.
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return ReplaceInstUsesWith(I, V == A ? B : A);
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// If we have: ((V + N) & C1) | (V & C2)
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// .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
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// replace with V+N.
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if (C1 == ConstantExpr::getNot(C2)) {
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Value *V1, *V2;
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if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
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match(A, m_Add(m_Value(V1), m_Value(V2)))) {
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// Add commutes, try both ways.
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if (V1 == B && MaskedValueIsZero(V2, C2))
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return ReplaceInstUsesWith(I, A);
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if (V2 == B && MaskedValueIsZero(V1, C2))
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return ReplaceInstUsesWith(I, A);
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}
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// Or commutes, try both ways.
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if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
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match(B, m_Add(m_Value(V1), m_Value(V2)))) {
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// Add commutes, try both ways.
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if (V1 == A && MaskedValueIsZero(V2, C1))
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return ReplaceInstUsesWith(I, B);
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if (V2 == A && MaskedValueIsZero(V1, C1))
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return ReplaceInstUsesWith(I, B);
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}
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}
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}
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