Subzero: Initial O2 lowering

src/IceGlobalContext.cpp

Index: src/IceGlobalContext.cpp
diff --git a/src/IceGlobalContext.cpp b/src/IceGlobalContext.cpp
index 7a21b401f36f2c5098bddecd0aa102504842a248..e4b2d892b76df07d687fb610f362e0c4797c0468 100644
--- a/src/IceGlobalContext.cpp
+++ b/src/IceGlobalContext.cpp
@@ -129,7 +129,9 @@ IceString GlobalContext::mangleName(const IceString &Name) const {
     return NewName;
   }
 
-  ItemsParsed = sscanf(Name.c_str(), "_Z%u%s", &BaseLength, NameBase);
+  // Artificially limit BaseLength to 9 digits (less than 1 billion)
+  // because sscanf behavior is undefined on integer overflow.

[JF, 2014/05/25 22:50:50]

Add an assert that has this comment.

[Jim Stichnoth, 2014/05/29 01:39:46]

An assert isn't appropriate here.  The idea is to try to demangle a C++ symbol
involving a namespace, and if that fails, fall back to adding a prefix to a
presumed C symbol.  (There is one test in mangle.ll that tests for such integer
overflow.)

I updated the comment, and also tried to improve the overflow check by testing
whether the following string starts with a digit.

+  ItemsParsed = sscanf(Name.c_str(), "_Z%9u%s", &BaseLength, NameBase);
   if (ItemsParsed == 2 && BaseLength <= strlen(NameBase)) {
     // Transform _Z3barxyz ==> _ZN6Prefix3barExyz
     //                           ^^^^^^^^    ^