[LLVMdev] Optimized "opt" on Darwin fails to load dynamic libraries with passes

[Harel Cain]

Hi all,

This is a problem that occurs for me only on Darwin (MacOS) and not on
Linux.

When llvm 2.8 (or 2.9) is compiled with ENABLE_OPTIMIZED=1, the "opt" tool
fails to load LLVM passes in dynamic libraries (.dylib) files, regardless of
how they themselves were built. When opt is built with ENABLE_OPTIMIZED=0,
all is well.

Here is some informative output. Seems to me the problem is in stripping the
symbols of the assignPassManager virtual method from the various subclasses
of llvm::Pass.

Please advise!


// the release version has all the necessary symbols in place before it is
installed to /usr/local/bin
$ nm -m Release+Asserts/bin/opt | grep assignPass
000000010042b7c0 (__TEXT,__text) external
__ZN4llvm10ModulePass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001002a27c0 (__TEXT,__text) external
__ZN4llvm10RegionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
000000010042b490 (__TEXT,__text) external
__ZN4llvm12FunctionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
000000010042b260 (__TEXT,__text) external
__ZN4llvm14BasicBlockPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001002053a0 (__TEXT,__text) external
__ZN4llvm16CallGraphSCCPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001004223d0 (__TEXT,__text) weak external
__ZN4llvm4Pass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
0000000100262120 (__TEXT,__text) external
__ZN4llvm8LoopPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001004d7936 (__TEXT,__cstring) non-external
__ZZN4llvm10ModulePass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004bcf42 (__TEXT,__cstring) non-external
__ZZN4llvm10RegionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004d7924 (__TEXT,__cstring) non-external
__ZZN4llvm12FunctionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004d7901 (__TEXT,__cstring) non-external
__ZZN4llvm14BasicBlockPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004b404f (__TEXT,__cstring) non-external
__ZZN4llvm16CallGraphSCCPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004b9ce0 (__TEXT,__cstring) non-external
__ZZN4llvm8LoopPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__

// same is true for the debug build
$ nm -m Debug+Asserts/bin/opt | grep assignPass
000000010040ea82 (__TEXT,__text) external
__ZN4llvm10ModulePass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
0000000100299a82 (__TEXT,__text) external
__ZN4llvm10RegionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
000000010040e8a0 (__TEXT,__text) external
__ZN4llvm12FunctionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
000000010040e758 (__TEXT,__text) external
__ZN4llvm14BasicBlockPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001001fcb5e (__TEXT,__text) external
__ZN4llvm16CallGraphSCCPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001004093a8 (__TEXT,__text) weak external
__ZN4llvm4Pass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
000000010025687e (__TEXT,__text) external
__ZN4llvm8LoopPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
00000001004e349b (__TEXT,__cstring) non-external
__ZZN4llvm10ModulePass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004c8414 (__TEXT,__cstring) non-external
__ZZN4llvm10RegionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004e3489 (__TEXT,__cstring) non-external
__ZZN4llvm12FunctionPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004e3466 (__TEXT,__cstring) non-external
__ZZN4llvm14BasicBlockPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004bf4e6 (__TEXT,__cstring) non-external
__ZZN4llvm16CallGraphSCCPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__
00000001004c5402 (__TEXT,__cstring) non-external
__ZZN4llvm8LoopPass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeEE8__func__

// however, once it is installed with "make install" to /usr/local/bin, it's
stripped of most of the relevant symbols (those of the llvm::Pass
subclasses)
$ nm -m /usr/local/bin/opt | grep assignPass
00000001004223d0 (__TEXT,__text) weak external
__ZN4llvm4Pass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE

// my dynamic library contains a ModulePass, with a matching symbol that is
missing in the installed "opt" binary
$ nm -m /usr/local/lib/libMyPass.dylib | grep assignPass
         (undefined) external
__ZN4llvm10ModulePass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE

// and indeed, when opt tries to load it, it fails.
$ opt -load /usr/local/lib/libMyPass.dylib
Error opening '/usr/local/lib/libMyPass.dylib':
dlopen(/usr/local/lib/libMyPass.dylib, 9): Symbol not found:
__ZN4llvm10ModulePass17assignPassManagerERNS_7PMStackENS_15PassManagerTypeE
  Referenced from: /usr/local/lib/libMyPass.dylib
  Expected in: flat namespace
 in /usr/local/lib/libMyPass.dylib
  -load request ignored.


Thanks a lot,

Harel Cain
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