GitLab

Motivation

While working on #18975 I realized that it can be really helpful to see how cc, as, ld, llc and opt are called by GHC.

This especially helped me to figure out some ABI and ISA issues.

Proposal

To help myself, I've added some quick&dirty prints:

builderMainLoop :: DynFlags -> (String -> String) -> FilePath
                -> [String] -> Maybe FilePath -> Maybe [(String, String)]
                -> IO ExitCode
builderMainLoop dflags filter_fn pgm real_args mb_cwd mb_env = do
  print "--------------------------------------------------------"
  print pgm
  print real_args
  print "--------------------------------------------------------"

(Process.hs)

This leads to outputs like:

...
"--------------------------------------------------------"
"/home/sven/src/llvm-project/build/bin/opt"
["-mem2reg","-globalopt","-lower-expect","-enable-tbaa","-tbaa","-relocation-model=pic","utils/hsc2hs/src/HSCParser.ll","-o","/home/sven/tmp/ghc/ghc18633_0/ghc_2.bc"]
"--------------------------------------------------------"
"--------------------------------------------------------"
"/home/sven/src/llvm-project/build/bin/llc"
["-O1","-enable-tbaa","-relocation-model=pic","-mcpu=mips64r2","-mattr=-noabicalls,+xgot,+long-calls","-force-mips-long-branch","/home/sven/tmp/ghc/ghc18633_0/ghc_2.bc","-o","/home/sven/tmp/ghc/ghc18633_0/ghc_3.lm_s"]
"--------------------------------------------------------"
"--------------------------------------------------------"
"mips64el-unknown-linux-gnu-cc"
["-iquoteutils/hsc2hs/src","-Iutils/hsc2hs/dist-install/build","-Iutils/hsc2hs/dist-install/build/hsc2hs/autogen","-Iutils/hsc2hs/dist-install/build","-no-pie","-fPIC","-U__PIC__","-D__PIC__","-mips64r2","-x","assembler","-c","utils/hsc2hs/src/HSCParser.s","-o","utils/hsc2hs/dist-install/build/HSCParser.o.tmp"]
...

I think it would be useful to enable similar debugging output with a flag.