[Re: strace for whole-program bitcodes]

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1

someone suggested me to use gold-plugin, I know nothing about it yet, I

will

have a try later. Does anyone have a good solution for this problem?

Afaik gold does not help here. I tried it and managed to only generate
native code.

"Just" gold isn't quite good enough, because at the last final link
steps gold will still generate native code. However, it should be
possible to find a way to get gold to leave the merged bitcode around
somewhere, or perhaps do something like llvm-ld. Nicholas?

I've had some success by adding a call to lto_codegen_write_merged_modules(cg, somePath) at the end of the gold plugin's all_symbols_read_hook() function just before it calls lto_codegen_dispose(cg). The somePath is set via a plugin option which I patched llvm-gcc to pass through as a derivation from its -o argument.

It has worked on several mid-complexity applications I've tried so far (lighttpd, wu-ftpd, tcdump, and the sqlite library).

I would be interested in seeing more of Timo's solution. My goal is to eventually have a way to get bitcode + lli script outputs for off the shelf applications without modifying their make files.

2

My way of getting whole program bitcodes is (you can use clang for CC)
for projects using autoconf and automake:
export CC=llvm-gcc
export CXX=llvm-g++
./configure --disable-shared
make CPPFLAGS="-O0 -g -emit-llvm" CCLD="llvm-ld -disable-opt" CFLAGS= -j4

I had to use CPPFLAGS instead of CFLAGS because llvm-ld doesn't
understand -O0 and -g, also it doesn't work to put CCLD on the configure
invocation line, it only works on the make invocation line.

Best regards,
--Edwin