[llvm] r316480 - [globalisel][tablegen] Fix future undefined behaviour in r316463.

[Daniel Sanders via llvm-commits]

Author: dsanders
Date: Tue Oct 24 11:11:54 2017
New Revision: 316480

URL: http://llvm.org/viewvc/llvm-project?rev=316480&view=rev
Log:
[globalisel][tablegen] Fix future undefined behaviour in r316463.

I missed a dereference of `Matched` that preceeded the new check. Thanks to
Justin Bogner for spotting it.

Modified:
    llvm/trunk/utils/TableGen/GlobalISelEmitter.cpp

Modified: llvm/trunk/utils/TableGen/GlobalISelEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/GlobalISelEmitter.cpp?rev=316480&r1=316479&r2=316480&view=diff
==============================================================================
--- llvm/trunk/utils/TableGen/GlobalISelEmitter.cpp (original)
+++ llvm/trunk/utils/TableGen/GlobalISelEmitter.cpp Tue Oct 24 11:11:54 2017
@@ -1758,13 +1758,16 @@ private:
 
   /// True if the instruction can be built solely by mutating the opcode.
   bool canMutate(RuleMatcher &Rule) const {
+    if (!Matched)
+      return false;
+
     if (OperandRenderers.size() != Matched->getNumOperands())
       return false;
 
     for (const auto &Renderer : enumerate(OperandRenderers)) {
       if (const auto *Copy = dyn_cast<CopyRenderer>(&*Renderer.value())) {
         const OperandMatcher &OM = Rule.getOperandMatcher(Copy->getSymbolicName());
-        if ((Matched != nullptr && Matched != &OM.getInstructionMatcher()) ||
+        if (Matched != &OM.getInstructionMatcher() ||
             OM.getOperandIndex() != Renderer.index())
           return false;
       } else