support multiplication by constant negative integers
this constmul code is still buggy though, so beware. mul by 7427 is currently
broken, for example. will fix it when I get a moment :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21652 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/IA64/IA64ISelPattern.cpp b/lib/Target/IA64/IA64ISelPattern.cpp
index 5ac5df5..badc89f 100644
--- a/lib/Target/IA64/IA64ISelPattern.cpp
+++ b/lib/Target/IA64/IA64ISelPattern.cpp
@@ -784,7 +784,7 @@
bool flippedSign;
unsigned preliminaryShift=0;
- assert(constant > 0 && "erk, don't multiply by zero or negative nums\n");
+ assert(constant != 0 && "erk, you're trying to multiply by constant zero\n");
// first, we make the constant to multiply by positive
if(constant<0) {
@@ -832,15 +832,24 @@
}
// don't forget flippedSign and preliminaryShift!
- SDOperand finalresult;
+ SDOperand shiftedresult;
if(preliminaryShift) {
SDOperand finalshift = ISelDAG->getConstant(preliminaryShift, MVT::i64);
- finalresult = ISelDAG->getNode(ISD::SHL, MVT::i64,
+ shiftedresult = ISelDAG->getNode(ISD::SHL, MVT::i64,
results[ops.size()-1], finalshift);
} else { // there was no preliminary divide-by-power-of-2 required
- finalresult = results[ops.size()-1];
+ shiftedresult = results[ops.size()-1];
}
+ SDOperand finalresult;
+ if(flippedSign) { // if we were multiplying by a negative constant:
+ SDOperand zero = ISelDAG->getConstant(0, MVT::i64);
+ // subtract the result from 0 to flip its sign
+ finalresult = ISelDAG->getNode(ISD::SUB, MVT::i64, zero, shiftedresult);
+ } else { // there was no preliminary multiply by -1 required
+ finalresult = shiftedresult;
+ }
+
return finalresult;
}