Check for metadata in PNaCl ABI checker.

tools/opt/opt.cpp

 //===- opt.cpp - The LLVM Modular Optimizer -------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // Optimizations may be specified an arbitrary number of times on the command
@@ skipping 568 matching lines @@
   // @LOCALMOD-BEGIN
   initializeExpandByValPass(Registry);
   initializeExpandConstantExprPass(Registry);
   initializeExpandCtorsPass(Registry);
   initializeExpandGetElementPtrPass(Registry);
   initializeExpandTlsPass(Registry);
   initializeExpandTlsConstantExprPass(Registry);
   initializeExpandVarArgsPass(Registry);
   initializeFlattenGlobalsPass(Registry);
   initializeGlobalCleanupPass(Registry);
-  initializePNaClABIVerifyFunctionsPass(Registry);

[jvoung (off chromium), 2013/04/25 17:30:25]

I'm not sure how to pass a flag to these generic initialize*Pass() functions, so
I think we would need to do "Passes.add(createPNaCl...(ErrReporter,
PNaClABIAllowDebug));" below.  Would you prefer extra mods like that, or just
modify pnacl-ld to run "pnacl-abicheck" separately after the expand passes? (see
current driver change).  That does make the linking a little slower, which could
affect autoconf-type things...

[Mark Seaborn, 2013/04/25 18:11:19]

You could have a "static cl::opt<bool>" in PNaClABIVerify*.cpp. 
lib/Transforms/Utils/LowerInvoke.cpp has one for "-enable-correct-eh-support". 
It's icky having a global variable for this, but LLVM seems to like it that way.

Probably you can't have this cl::opt as static if you need this option for two
passes.  I'm not sure this really needs to be two separate passes, though?

[jvoung (off chromium), 2013/04/25 23:22:20]

I think it's separate for streaming -- one is a module-level pass that never
touches functions, and the other is a function-level pass.  Perhaps they can be
defined in the same file though...

Ended up extern'ing the commandline flag.  There's one case in
include/llvm/CodeGen/MachineScheduler.h "extern cl::opt<bool> ForceBottomUp;"
and a couple cases in lib/Target, but it is rare =/

[Derek Schuff, 2013/04/26 00:34:34]

On 2013/04/25 23:22:20, jvoung (cr) wrote:
The separation is for streaming. There are a few extern flag decls lying around.
Also in our MIPS port, Petar re-used the sfi-foo flags we had for ARM, which is
even worse because they are in different libraries. It's only by accident that
our CMake shared library build successfully links (it doesn't on mac).

-  initializePNaClABIVerifyModulePass(Registry);
   initializeResolveAliasesPass(Registry);
   initializeStripMetadataPass(Registry);
   // @LOCALMOD-END
 
   cl::ParseCommandLineOptions(argc, argv,
     "llvm .bc -> .bc modular optimizer and analysis printer\n");
 
   if (AnalyzeOnly && NoOutput) {
     errs() << argv[0] << ": analyze mode conflicts with no-output mode.\n";
     return 1;
@@ skipping 235 matching lines @@
 
   // Now that we have all of the passes ready, run them.
   Passes.run(*M.get());
 
   // Declare success.
   if (!NoOutput || PrintBreakpoints)
     Out->keep();
 
   return 0;
 }