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Codegen this:

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int %foo(int %X) {
        %T = add int %X, 13
        %S = mul int %T, 3
        ret int %S
}

as this:

        mov %ECX, DWORD PTR [%ESP + 4]
        lea %EAX, DWORD PTR [%ECX + 2*%ECX + 39]
        ret

instead of this:

        mov %ECX, DWORD PTR [%ESP + 4]
        mov %EAX, %ECX
        add %EAX, 13
        imul %EAX, %EAX, 3
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19633 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-01-17 06:48:02 +00:00
parent 7a866d9a43
commit 2a4e508281
1 changed files with 18 additions and 0 deletions
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18
lib/Target/X86/X86ISelPattern.cpp
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@ -1636,6 +1636,24 @@ unsigned ISel::SelectExpr(SDOperand N) {
}
}
// Fold common multiplies into LEA instructions.
if (Node->getOpcode() == ISD::MUL && N.getValueType() == MVT::i32) {
switch ((int)CN->getValue()) {
default: break;
case 3:
case 5:
case 9:
X86AddressMode AM;
// Remove N from exprmap so SelectAddress doesn't get confused.
ExprMap.erase(N);
SelectAddress(N, AM);
// Restore it to the map.
ExprMap[N] = Result;
addFullAddress(BuildMI(BB, X86::LEA32r, 4, Result), AM);
return Result;
}
}
switch (N.getValueType()) {
default: assert(0 && "Cannot xor this type!");
case MVT::i1: