Fix subzero build for mac

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 95 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::SmallVector<char, 32> NameBase(1 + Name.length());
   const size_t BufLen = 30 + Name.length() + PrefixLength;
-  char NewName[BufLen];
+  llvm::SmallVector<char, 32> NewName(BufLen);
   uint32_t BaseLength = 0; // using uint32_t due to sscanf format string
 
-  int ItemsParsed = sscanf(Name.c_str(), "_ZN%s", NameBase);
+  int ItemsParsed = sscanf(Name.c_str(), "_ZN%s", NameBase.data());
   if (ItemsParsed == 1) {
     // Transform _ZN3foo3barExyz ==> _ZN6Prefix3foo3barExyz
     //   (splice in "6Prefix")          ^^^^^^^
-    snprintf(NewName, BufLen, "_ZN%u%s%s", PrefixLength,
-             getTestPrefix().c_str(), NameBase);
+    snprintf(NewName.data(), BufLen, "_ZN%u%s%s", PrefixLength,
+             getTestPrefix().c_str(), NameBase.data());
     // 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;
+    return NewName.data();
   }
 
   // Artificially limit BaseLength to 9 digits (less than 1 billion)
   // because sscanf behavior is undefined on integer overflow.  If
   // there are more than 9 digits (which we test by looking at the
   // beginning of NameBase), then we consider this a failure to parse
   // a namespace mangling, and fall back to the simple prefixing.
-  ItemsParsed = sscanf(Name.c_str(), "_Z%9u%s", &BaseLength, NameBase);
-  if (ItemsParsed == 2 && BaseLength <= strlen(NameBase) &&
+  ItemsParsed = sscanf(Name.c_str(), "_Z%9u%s", &BaseLength, NameBase.data());
+  if (ItemsParsed == 2 && BaseLength <= strlen(NameBase.data()) &&
       !isdigit(NameBase[0])) {
     // 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::SmallVector<char, 32> OrigName(Name.length());
+    llvm::SmallVector<char, 32> OrigSuffix(Name.length());
     uint32_t ActualBaseLength = BaseLength;
     if (NameBase[ActualBaseLength] == 'I') {
       ++ActualBaseLength;
       while (NameBase[ActualBaseLength] != 'E' &&
              NameBase[ActualBaseLength] != '\0')
         ++ActualBaseLength;
     }
-    strncpy(OrigName, NameBase, ActualBaseLength);
+    strncpy(OrigName.data(), NameBase.data(), ActualBaseLength);
     OrigName[ActualBaseLength] = '\0';
-    strcpy(OrigSuffix, NameBase + ActualBaseLength);
-    snprintf(NewName, BufLen, "_ZN%u%s%u%sE%s", PrefixLength,
-             getTestPrefix().c_str(), BaseLength, OrigName, OrigSuffix);
-    return NewName;
+    strcpy(OrigSuffix.data(), NameBase.data() + ActualBaseLength);
+    snprintf(NewName.data(), BufLen, "_ZN%u%s%u%sE%s", PrefixLength,
+             getTestPrefix().c_str(), BaseLength, OrigName.data(),
+             OrigSuffix.data());
+    return NewName.data();
   }
 
   // Transform bar ==> Prefixbar
   //                   ^^^^^^
   return getTestPrefix() + Name;
 }
 
 GlobalContext::~GlobalContext() {}
 
 Constant *GlobalContext::getConstantInt(Type Ty, uint64_t ConstantInt64) {
@@ skipping 36 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