[CodeGenPrepare] Fix the check of the legality of an instruction.

The API expects an ISD opcode, not an IR opcode.
Fixes a regression for R600.

Related to <rdar://problem/15519855>.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201923 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CodeGenPrepare.cpp

@@ -1756,7 +1756,12 @@ AddressingModeMatcher::IsPromotionProfitable(unsigned MatchedSize,
   Instruction *PromotedInst = dyn_cast<Instruction>(PromotedOperand);
   if (!PromotedInst)
     return false;
-  return TLI.isOperationLegalOrCustom(PromotedInst->getOpcode(),
+  int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
+  // If the ISDOpcode is undefined, it was undefined before the promotion.
+  if (!ISDOpcode)
+    return true;
+  // Otherwise, check if the promoted instruction is legal or not.
+  return TLI.isOperationLegalOrCustom(ISDOpcode,
                                       EVT::getEVT(PromotedInst->getType()));
 }