Changes in directory llvm/lib/CodeGen/SelectionDAG:
SelectionDAG.cpp updated: 1.300 -> 1.301
---
Log message:
Implement folding of a bunch of binops with undef
---
Diffs of the changes: (+46 -0)
SelectionDAG.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 46 insertions(+)
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.300
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.301
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.300 Sat Apr 15
18:38:00 2006
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Thu Apr 20 00:39:12 2006
@@ -1367,6 +1367,52 @@
}
}
}
+
+ // Canonicalize an UNDEF to the RHS, even over a constant.
+ if (N1.getOpcode() == ISD::UNDEF) {
+ if (isCommutativeBinOp(Opcode)) {
+ std::swap(N1, N2);
+ } else {
+ switch (Opcode) {
+ case ISD::FP_ROUND_INREG:
+ case ISD::SIGN_EXTEND_INREG:
+ case ISD::SUB:
+ case ISD::FSUB:
+ case ISD::FDIV:
+ case ISD::FREM:
+ return N1; // fold op(undef, arg2) -> undef
+ case ISD::UDIV:
+ case ISD::SDIV:
+ case ISD::UREM:
+ case ISD::SREM:
+ return getConstant(0, VT); // fold op(undef, arg2) -> 0
+ }
+ }
+ }
+
+ // Fold a bunch of operators that
+ if (N2.getOpcode() == ISD::UNDEF) {
+ switch (Opcode) {
+ case ISD::ADD:
+ case ISD::SUB:
+ case ISD::FADD:
+ case ISD::FSUB:
+ case ISD::FMUL:
+ case ISD::FDIV:
+ case ISD::FREM:
+ case ISD::UDIV:
+ case ISD::SDIV:
+ case ISD::UREM:
+ case ISD::SREM:
+ case ISD::XOR:
+ return N2; // fold op(arg1, undef) -> undef
+ case ISD::MUL:
+ case ISD::AND:
+ return getConstant(0, VT); // fold op(arg1, undef) -> 0
+ case ISD::OR:
+ return getConstant(MVT::getIntVTBitMask(VT), VT);
+ }
+ }
// Finally, fold operations that do not require constants.
switch (Opcode) {
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