Subzero: Fix over-aggressive bool folding.

src/IceInst.cpp

Index: src/IceInst.cpp
diff --git a/src/IceInst.cpp b/src/IceInst.cpp
index aac42c3bd2f98823a6a1a0d622c6f4558210f1d2..99d8868c58c812fa3af03ba12c12cba2c6d7d9f9 100644
--- a/src/IceInst.cpp
+++ b/src/IceInst.cpp
@@ -188,6 +188,10 @@ void Inst::spliceLivenessInfo(Inst *OrigInst, Inst *SpliceAssn) {
   llvm::report_fatal_error("Failed to find splice operand");
 }
 
+bool Inst::isMemoryWrite() const {
+  llvm::report_fatal_error("Attempt to call base Inst::isMemoryWrite() method");
+}
+
 void Inst::livenessLightweight(Cfg *Func, LivenessBV &Live) {
   assert(!isDeleted());
   resetLastUses();