Valgrind reports that many OpaqueType objects are routinely leaked by LLVM,
routinely adding up to 1.5MB or so.

-Chris

The main patch is here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20031222/010442.html

The problem was that the PATypeHolder object was addref'ing types when it was
created, but not dropRef'ing the type when it was destroyed.  Whoops.

Fixing this exposed the following latent bugs in the asmparser:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20031222/010439.html
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20031222/010440.html

-Chris

Oh in case anyone cares, here's the typical valgrind output that this fixes:

64 bytes in 1 blocks are definitely lost in loss record 2 of 4
  at 0x40028B85: __builtin_new (vg_replace_malloc.c:172)
  by 0x40028BF0: operator new(unsigned) (vg_replace_malloc.c:185)
  by 0x8242F83: llvm::OpaqueType::get() (DerivedTypes.h:430)
  by 0x8231BB5: llvm::getTypeVal(llvm::ValID const&, bool) (llvmAsmParser.y:274)
  by 0x8234CE4: llvmAsmparse() (llvmAsmParser.y:913)
  by 0x82337F6: llvm::RunVMAsmParser(std::string const&, _IO_FILE*)
(llvmAsmParser.y:643)
  by 0x8231213: llvm::ParseAssemblyFile(std::string const&) (Parser.cpp:35)
  by 0x822D71C: main (gccas.cpp:105)

Though anything that creates Opaque or otherwise abstract types can be found to
be the leak, including the bytecode reader.

-Chris