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Implement a couple of more simplifications. This lets us codegen:
int test2(int * P, int* Q, int A, int B) { return P+A == P; } into: test2: movl 4(%esp), %eax movl 12(%esp), %eax shll $2, %eax cmpl $0, %eax sete %al movzbl %al, %eax ret instead of: test2: movl 4(%esp), %eax movl 12(%esp), %ecx leal (%eax,%ecx,4), %ecx cmpl %eax, %ecx sete %al movzbl %al, %eax ret ICC is producing worse code: test2: movl 4(%esp), %eax #8.5 movl 12(%esp), %edx #8.5 lea (%edx,%edx), %ecx #9.9 addl %ecx, %ecx #9.9 addl %eax, %ecx #9.9 cmpl %eax, %ecx #9.16 movl $0, %eax #9.16 sete %al #9.16 ret #9.16 as is GCC (looks like our old code): test2: movl 4(%esp), %edx movl 12(%esp), %eax leal (%edx,%eax,4), %ecx cmpl %edx, %ecx sete %al movzbl %al, %eax ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19430 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -398,23 +398,54 @@ SDOperand SelectionDAG::getSetCC(ISD::CondCode Cond, SDOperand N1,
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Cond = UOF == 0 ? ISD::SETUO : ISD::SETO;
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}
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// Simplify (X+Y) == (X+Z) --> Y == Z
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if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
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N1.getOpcode() == N2.getOpcode() && MVT::isInteger(N1.getValueType()))
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if (N1.getOpcode() == ISD::ADD || N1.getOpcode() == ISD::SUB) {
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if (N1.getOperand(0) == N2.getOperand(0))
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return getSetCC(Cond, N1.getOperand(1), N2.getOperand(1));
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if (N1.getOperand(1) == N2.getOperand(1))
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return getSetCC(Cond, N1.getOperand(0), N2.getOperand(0));
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if (isCommutativeBinOp(N1.getOpcode())) {
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// If X op Y == Y op X, try other combinations.
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if (N1.getOperand(0) == N2.getOperand(1))
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return getSetCC(Cond, N1.getOperand(1), N2.getOperand(0));
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if (N1.getOperand(1) == N2.getOperand(0))
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MVT::isInteger(N1.getValueType())) {
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if (N1.getOpcode() == ISD::ADD || N1.getOpcode() == ISD::SUB ||
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N1.getOpcode() == ISD::XOR) {
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// Simplify (X+Y) == (X+Z) --> Y == Z
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if (N1.getOpcode() == N2.getOpcode()) {
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if (N1.getOperand(0) == N2.getOperand(0))
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return getSetCC(Cond, N1.getOperand(1), N2.getOperand(1));
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if (N1.getOperand(1) == N2.getOperand(1))
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return getSetCC(Cond, N1.getOperand(0), N2.getOperand(0));
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if (isCommutativeBinOp(N1.getOpcode())) {
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// If X op Y == Y op X, try other combinations.
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if (N1.getOperand(0) == N2.getOperand(1))
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return getSetCC(Cond, N1.getOperand(1), N2.getOperand(0));
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if (N1.getOperand(1) == N2.getOperand(0))
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return getSetCC(Cond, N1.getOperand(1), N2.getOperand(1));
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}
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}
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// Simplify (X+Z) == X --> Z == 0
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if (N1.getOperand(0) == N2)
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return getSetCC(Cond, N1.getOperand(1),
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getConstant(0, N1.getValueType()));
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if (N1.getOperand(1) == N2) {
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if (isCommutativeBinOp(N1.getOpcode()))
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return getSetCC(Cond, N1.getOperand(0),
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getConstant(0, N1.getValueType()));
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else {
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assert(N1.getOpcode() == ISD::SUB && "Unexpected operation!");
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// (Z-X) == X --> Z == X<<1
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return getSetCC(Cond, N1.getOperand(0),
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getNode(ISD::SHL, N2.getValueType(),
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N2, getConstant(1, MVT::i8)));
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}
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}
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}
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if (N2.getOpcode() == ISD::ADD || N2.getOpcode() == ISD::SUB ||
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N2.getOpcode() == ISD::XOR) {
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// Simplify X == (X+Z) --> Z == 0
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if (N2.getOperand(0) == N1)
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return getSetCC(Cond, N2.getOperand(1),
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getConstant(0, N2.getValueType()));
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else if (N2.getOperand(1) == N1)
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return getSetCC(Cond, N2.getOperand(0),
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getConstant(0, N2.getValueType()));
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}
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}
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SetCCSDNode *&N = SetCCs[std::make_pair(std::make_pair(N1, N2), Cond)];
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if (N) return SDOperand(N, 0);
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