A bugfix for tblgen, in the function ‘emitSourceFileHeader’.

When the first parameter (‘Desc’) is more than 80 characters long, it will result the header line that contains the description to be more
Than (4GB!) long. Not only it takes forever to produce, the output file cannot be open, since its ginormous.

Patch by Elior Malul.

llvm-svn: 173672

1 files changed, 25 insertions, 6 deletions

diff --git a/llvm/lib/TableGen/TableGenBackend.cpp b/llvm/lib/TableGen/TableGenBackend.cpp
index 7c8367a..79d5677 100644
--- a/llvm/lib/TableGen/TableGenBackend.cpp
+++ b/llvm/lib/TableGen/TableGenBackend.cpp
@@ -14,13 +14,20 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TableGen/TableGenBackend.h"
+#include <algorithm>
+
 using namespace llvm;
 
+const size_t MAX_LINE_LEN = 80U;
+
 static void printLine(raw_ostream &OS, const Twine &Prefix, char Fill,
                       StringRef Suffix) {
-  uint64_t Pos = OS.tell();
+  size_t Pos = (size_t)OS.tell();
+  assert((MAX_LINE_LEN - Prefix.str().size() - Suffix.size() > 0) &&
+    "header line exceeds max limit");
   OS << Prefix;
-  for (unsigned i = OS.tell() - Pos, e = 80 - Suffix.size(); i != e; ++i)
+  const size_t e = MAX_LINE_LEN - Suffix.size();
+  for (size_t i = (size_t)OS.tell() - Pos; i < e; ++i)
     OS << Fill;
   OS << Suffix << '\n';
 }
@@ -28,10 +35,22 @@ static void printLine(raw_ostream &OS, const Twine &Prefix, char Fill,
 void llvm::emitSourceFileHeader(StringRef Desc, raw_ostream &OS) {
   printLine(OS, "/*===- TableGen'erated file ", '-', "*- C++ -*-===*\\");
   printLine(OS, "|*", ' ', "*|");
-  printLine(OS, "|* " + Desc, ' ', "*|");
-  printLine(OS, "|*", ' ', "*|");
-  printLine(OS, "|* Automatically generated file, do not edit!", ' ', "*|");
-  printLine(OS, "|*", ' ', "*|");
+  size_t Pos = 0U;
+  size_t PosE;
+  StringRef Prefix("|*");
+  StringRef Suffix(" *|");
+  do{
+    size_t PSLen = Suffix.size() + Prefix.size();
+    PosE = Pos + ((MAX_LINE_LEN > (Desc.size() - PSLen)) ?
+      Desc.size() :
+      MAX_LINE_LEN - PSLen);
+    printLine(OS, Prefix + Desc.slice(Pos, PosE), ' ', Suffix);
+    Pos = PosE;
+  } while(Pos < Desc.size());
+  printLine(OS, Prefix, ' ', Suffix);
+  printLine(OS, Prefix + " Automatically generated file, do not edit!", ' ',
+    Suffix);
+  printLine(OS, Prefix, ' ', Suffix);
   printLine(OS, "\\*===", '-', "===*/");
   OS << '\n';
 }