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Remove some redundant checks, add a couple of new ones. This allows us to

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compile this:

int foo (unsigned long a, unsigned long long g) {
  return a >= g;
}

To:

foo:
        movl 8(%esp), %eax
        cmpl %eax, 4(%esp)
        setae %al
        cmpl $0, 12(%esp)
        sete %cl
        andb %al, %cl
        movzbl %cl, %eax
        ret

instead of:

foo:
        movl 8(%esp), %eax
        cmpl %eax, 4(%esp)
        setae %al
        movzbw %al, %cx
        movl 12(%esp), %edx
        cmpl $0, %edx
        sete %al
        movzbw %al, %ax
        cmpl $0, %edx
        cmove %cx, %ax
        movzbl %al, %eax
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21244 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-04-12 02:54:39 +00:00
parent 5b95ed652f
commit fd1f1ee0ba
1 changed files with 5 additions and 7 deletions
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12
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -960,12 +960,6 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
if (VT == MVT::i1) { // Boolean SELECT
if (N2C) {
if (N3C) {
if (N2C->getValue()) // select C, 1, 0 -> C
return N1;
return getNode(ISD::XOR, VT, N1, N3); // select C, 0, 1 -> ~C
}
if (N2C->getValue()) // select C, 1, X -> C | X
return getNode(ISD::OR, VT, N1, N3);
else // select C, 0, X -> ~C & X
@ -980,6 +974,11 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
else // select C, X, 0 -> C & X
return getNode(ISD::AND, VT, N1, N2);
}
if (N1 == N2) // X ? X : Y --> X ? 1 : Y --> X | Y
return getNode(ISD::OR, VT, N1, N3);
if (N1 == N3) // X ? Y : X --> X ? Y : 0 --> X & Y
return getNode(ISD::AND, VT, N1, N2);
}
// If this is a selectcc, check to see if we can simplify the result.
@ -1001,7 +1000,6 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
N2.getOperand(0) == N3)
return getNode(ISD::FABS, VT, N3);
}
}
break;
case ISD::BRCOND: