compiler_rt testing

[jkthorne]

I have been trying to test the compiler_rt flag and am a bit confused. It seems like the file is being loaded and the functions are not being used.

I have put a raise "testing" inside the __mulodi4 rt function.
https://github.com/crystal-lang/crystal/blob/master/src/crystal/compiler_rt.cr#L4

After building crystal and running .build/crystal eval "puts 1_i64 * 1_i64" I would expect crystal to raise "testing" and it does not.

I have checked the build output and the "compiler_rt" flag is being passed.

$ make
Using /usr/local/opt/llvm@6/bin/llvm-config [version=6.0.1]
c++ -c  -o src/llvm/ext/llvm_ext.o src/llvm/ext/llvm_ext.cc -I/usr/local/Cellar/llvm@6/6.0.1_1/include  -stdlib=libc++ -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -std=c++11 -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -DNDEBUG   -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
cc -fPIC    -c -o src/ext/sigfault.o src/ext/sigfault.c
ar -rcs src/ext/libcrystal.a src/ext/sigfault.o
CRYSTAL_CONFIG_PATH="/Users/jack/source_code/open_source/crystal/src" CRYSTAL_CONFIG_LIBRARY_PATH="/usr/local/Cellar/crystal/0.28.0/embedded/lib" CRYSTAL_CONFIG_BUILD_COMMIT="8e3075027" ./bin/crystal build -D preview_overflow -D compiler_rt  -o .build/crystal src/compiler/crystal.cr -D without_openssl -D without_zlib

also if I put a raise in the file itself after the compile check and it seems like the file is being loaded.

Am I missing something?

[asterite]

You need to use bin/crystal

[asterite]

instead of .build/crystal

[jkthorne]

@asterite I just rebuilt on master and I am still not seeing a raise.

$ bin/crystal eval "puts 1_i64 * 1_i64"
Using compiled compiler at `.build/crystal'
1

[asterite]

Because multiplying two int64 is just an llmv primitive (I think mul), I don't see why compiler rt would be involved.

[asterite]

Oh, it's with overflow. Did you try with -D preview_overflow?

[jkthorne]

When building the compiler -D preview_overflow is there.

I am pretty sure the file is being loaded.
When I cause an overflow I am kind of suprised by the results but that seems like another issue.

[asterite]

You need to pass the flag when compiling any program, not just the compiler. I don't think bin crystal passes it.

[jkthorne]

It seems like it still does not work how I would expect.

$ bin/crystal eval "puts 1_i64 * 1_i64" -D preview_overflow -D compiler_rt
Using compiled compiler at `.build/crystal'
1

[asterite]

There could be many reasons:

• LLVM notices the result is obvious and doesn't need to call that function
• compiler_rt isn't used in all platforms

[jkthorne]

I have tried compiling this on linux and I have been getting the same results.

I am curious I have not used fun on the top-level before.
Is that where it should go?

[ysbaddaden]

AFAIK compiler_rt is only used on a few platforms that miss some features (i.e. Int128 on i386 arch). It's not used or linked for anything else or any other architecture.

I.e. it's just a convenience to implement some features that would be otherwise broken on some targets. It's not used unless it really has to.

[bcardiff]

@ysbaddaden is right. The compiler_rt.cr is used in 32bits arch to multiply 64 bits integers.
In 64 bits the 64bits multiplication (ie: @llvm.smul.with.overflow.i64 do not use __mulodi4)