[llvm-commits] Patch review for bug 9190

[Rotem, Nadav]

http://llvm.org/bugs/show_bug.cgi?id=9190

The bug happens when the DAGCombiner attempts to optimize one of the patterns of the SUB opcode. It tries to create a zero of type v2i64. This type is legal on 32bit machines, but the initializer is target dependent. Currently, the initializer attempts to create an i64 zero constant, which fails.
Added a flag to tell the DAGCombiner to create a legal zero, if we require that the pass would generate legal types.

Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp          (revision 124985)
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp       (working copy)
@@ -1533,7 +1533,7 @@
   // fold (sub x, x) -> 0
   if (N0 == N1)
-    return DAG.getConstant(0, N->getValueType(0));
+    return DAG.getConstant(0, N->getValueType(0), LegalTypes);
   // fold (sub c1, c2) -> c1-c2
   if (N0C && N1C)
     return DAG.FoldConstantArithmetic(ISD::SUB, VT, N0C, N1C);


Cheers,
Nadav
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