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Codegen this:
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
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@ -1636,6 +1636,24 @@ unsigned ISel::SelectExpr(SDOperand N) {
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}
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}
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// Fold common multiplies into LEA instructions.
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if (Node->getOpcode() == ISD::MUL && N.getValueType() == MVT::i32) {
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switch ((int)CN->getValue()) {
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default: break;
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case 3:
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case 5:
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case 9:
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X86AddressMode AM;
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// Remove N from exprmap so SelectAddress doesn't get confused.
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ExprMap.erase(N);
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SelectAddress(N, AM);
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// Restore it to the map.
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ExprMap[N] = Result;
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addFullAddress(BuildMI(BB, X86::LEA32r, 4, Result), AM);
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return Result;
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}
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}
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switch (N.getValueType()) {
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default: assert(0 && "Cannot xor this type!");
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case MVT::i1:
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