Fix g++ -pedantic warnings

src/IceGlobalContext.cpp

 //===- subzero/src/IceGlobalContext.cpp - Global context defs ---*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines aspects of the compilation that persist across
@@ skipping 81 matching lines @@
   //   _ZN3foo3barExyz ==> _ZN6Prefix3foo3barExyz
   // A non-nested but mangled name like bar() gets nested, making it
   // equivalent to Prefix::bar().
   //   _Z3barxyz ==> ZN6Prefix3barExyz
   // An unmangled, extern "C" style name, gets a simple prefix:
   //   bar ==> Prefixbar
   if (getTestPrefix().empty())
     return Name;
 
   unsigned PrefixLength = getTestPrefix().length();
-  char NameBase[1 + Name.length()];
+  llvm::OwningArrayPtr<char> NameBaseOwner(new char[1 + Name.length()]);

[JF, 2014/05/23 16:45:22]

Ew. VLAs aren't that evil in this context... What was the issue, just a VLA
warning? Can you allocate a statically-sized array that's realistically smaller
than any name?

[Jim Stichnoth, 2014/05/23 18:26:45]

I don't know what the maximum identifier length is (509?), but can't you make
the input string to mangleName() arbitrarily long just by embedding something
within an arbitrary nesting of namespaces?

Also, maximum-length arrays, ick.

Since it's a silly issue to start with, and it's isolated to this one function
that is just used for testing, I've rolled back the VLA-related changes and we
can revisit if the Mac bots complain.

+  char *NameBase = NameBaseOwner.get();
   const size_t BufLen = 30 + Name.length() + PrefixLength;
-  char NewName[BufLen];
+  llvm::OwningArrayPtr<char> NewNameOwner(new char[BufLen]);
+  char *NewName = NewNameOwner.get();
   uint32_t BaseLength = 0; // using uint32_t due to sscanf format string
 
   int ItemsParsed = sscanf(Name.c_str(), "_ZN%s", NameBase);
   if (ItemsParsed == 1) {
     // Transform _ZN3foo3barExyz ==> _ZN6Prefix3foo3barExyz
     //   (splice in "6Prefix")          ^^^^^^^
     snprintf(NewName, BufLen, "_ZN%u%s%s", PrefixLength,
              getTestPrefix().c_str(), NameBase);
     // We ignore the snprintf return value (here and below).  If we
     // somehow miscalculated the output buffer length, the output will
     // be truncated, but it will be truncated consistently for all
     // mangleName() calls on the same input string.
     return NewName;
   }
 
   ItemsParsed = sscanf(Name.c_str(), "_Z%u%s", &BaseLength, NameBase);
   if (ItemsParsed == 2 && BaseLength <= strlen(NameBase)) {
     // Transform _Z3barxyz ==> _ZN6Prefix3barExyz
     //                           ^^^^^^^^    ^
     // (splice in "N6Prefix", and insert "E" after "3bar")
     // But an "I" after the identifier indicates a template argument
     // list terminated with "E"; insert the new "E" before/after the
     // old "E".  E.g.:
     // Transform _Z3barIabcExyz ==> _ZN6Prefix3barIabcEExyz
     //                                ^^^^^^^^         ^
     // (splice in "N6Prefix", and insert "E" after "3barIabcE")
-    char OrigName[Name.length()];
-    char OrigSuffix[Name.length()];
+    llvm::OwningArrayPtr<char> OrigNameOwner(new char[Name.length()]);
+    char *OrigName = OrigNameOwner.get();
+    llvm::OwningArrayPtr<char> OrigSuffixOwner(new char[Name.length()]);
+    char *OrigSuffix = OrigSuffixOwner.get();
     uint32_t ActualBaseLength = BaseLength;
     if (NameBase[ActualBaseLength] == 'I') {
       ++ActualBaseLength;
       while (NameBase[ActualBaseLength] != 'E' &&
              NameBase[ActualBaseLength] != '\0')
         ++ActualBaseLength;
     }
     strncpy(OrigName, NameBase, ActualBaseLength);
     OrigName[ActualBaseLength] = '\0';
     strcpy(OrigSuffix, NameBase + ActualBaseLength);
@@ skipping 30 matching lines @@
 
 void Timer::printElapsedUs(GlobalContext *Ctx, const IceString &Tag) const {
   if (Ctx->isVerbose(IceV_Timing)) {
     // Prefixing with '#' allows timing strings to be included
     // without error in textual assembly output.
     Ctx->getStrDump() << "# " << getElapsedUs() << " usec " << Tag << "\n";
   }
 }
 
 } // end of namespace Ice