Bump compiler-builtins to 0.1.15

[alexcrichton]

This commit bumps the compiler-builtins dependency to 0.1.15 which
expects to have the source for compiler-rt provided externally if the
c feature is enabled. This then plumbs through the necessary support
in the build system to ensure that if the llvm-project directory is
checked out and present that we enable the c feature of
compiler-builtins and compile in all the C intrinsics.

[alexcrichton]

r? @cuviper

[rust-highfive]

r? @nikomatsakis

(rust_highfive has picked a reviewer for you, use r? to override)

[cuviper]

What is the impact of not having that c feature enabled? e.g. Can a Linux target build without it? I know that GCC as the "cc" linker will include libgcc.a, which also implements a lot of builtins...

[alexcrichton]

The theoretical impact is that some binaries won't link if an intrinsic hasn't been ported from C to Rust (although that's pretty rare) or a binary may run a bit slower if an optimized assembly routine isn't included and instead a slower Rust routine is. Our distribution targets don't need it enabled afaik but we've never tried to build them without it afaik.

This is probably going to regress something somewhere, but nothing major that I know of in the sense that it's probably some esoteric configuration in one way or another.

[cuviper]

OK, I just connected the dots on #[maybe_use_optimized_c_shim] too. Can you extend the comment in compile.rs to give readers a clue? We should get a builder testing this configuration too -- I suppose x86_64-gnu-llvm-6.0 is the best candidate, if we just avoid its LLVM in init_repo.sh.

[alexcrichton]

A better comment definitely makes sense, but I don't really know of a great way to test this on CI that isn't overly invasive to our current config :(

[cuviper]

OK, thanks. I'll think more about CI myself, but I did test it locally too.

@bors r+

[bors]

📌 Commit 69c6326 has been approved by cuviper

[bors]

⌛ Testing commit 69c6326 with merge 4e4e986f9dc43c199ff1971ddc5d90ecf3c18d1c...

[bors]

💔 Test failed - checks-travis

[rust-highfive]

The job dist-aarch64-linux of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:03:49] --- stdout
[00:03:49] TARGET = Some("x86_64-unknown-linux-gnu")
[00:03:49] OPT_LEVEL = Some("2")
[00:03:49] HOST = Some("x86_64-unknown-linux-gnu")
[00:03:49] CC_x86_64-unknown-linux-gnu = Some("sccache cc")
[00:03:49] CFLAGS_x86_64-unknown-linux-gnu = Some("-ffunction-sections -fdata-sections -fPIC -m64")
[00:03:49] CRATE_CC_NO_DEFAULTS = None
[00:03:49] DEBUG = Some("false")
[00:03:49] CARGO_CFG_TARGET_FEATURE = Some("fxsr,mmx,sse,sse2")
[00:03:49] running: "sccache" "cc" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-fno-builtin" "-fvisibility=hidden" "-fomit-frame-pointer" "-ffreestanding" "-DVISIBILITY_HIDDEN" "-DCOMPILER_RT_HAS_UNAME=1" "-DCOMPILER_RT_HAS_FCNTL_LCK=1" "-DCOMPILER_RT_HAS_ATOMICS=1" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-std/x86_64-unknown-linux-gnu/release/build/profiler_builtins-98e28db5f13c3bec/out/GCDAProfiling.o" "-c" "/cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.15/compiler-rt/lib/profile/GCDAProfiling.c"
[00:03:49] cargo:warning=cc: error: /cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.15/compiler-rt/lib/profile/GCDAProfiling.c: No such file or directory
[00:03:49] cargo:warning=cc: warning: '-x c' after last input file has no effect
[00:03:49] cargo:warning=cc: fatal error: no input files
[00:03:49] cargo:warning=compilation terminated.
[00:03:49] [00:03:49] --- stderr
[00:03:49] thread 'main' panicked at '
[00:03:49] [00:03:49] [00:03:49] Internal error occurred: Command "sccache" "cc" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-fno-builtin" "-fvisibility=hidden" "-fomit-frame-pointer" "-ffreestanding" "-DVISIBILITY_HIDDEN" "-DCOMPILER_RT_HAS_UNAME=1" "-DCOMPILER_RT_HAS_FCNTL_LCK=1" "-DCOMPILER_RT_HAS_ATOMICS=1" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-std/x86_64-unknown-linux-gnu/release/build/profiler_builtins-98e28db5f13c3bec/out/GCDAProfiling.o" "-c" "/cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.15/compiler-rt/lib/profile/GCDAProfiling.c" with args "cc" did not execute successfully (status code exit code: 1).
[00:03:49] ', /cargo/registry/src/github.com-1ecc6299db9ec823/cc-1.0.35/src/lib.rs:2398:5
[00:03:49] note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[00:03:49] [00:03:49] warning: build failed, waiting for other jobs to finish...
---
travis_time:end:342b0232:start=1558399180038769625,finish=1558399180044269164,duration=5499539
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:14539ad5
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:18601eee
travis_time:start:18601eee
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:025cd52a
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[Centril]

@bors retry

Not fully sure if spurious or not...

[cuviper]

cc: error: /cargo/registry/src/github.com-1ecc6299db9ec823/compiler_builtins-0.1.15/compiler-rt/lib/profile/GCDAProfiling.c: No such file or directory

That path isn't valid -- it should be using something under src/llvm-project/ now.

@bors r-

[bors]

📌 Commit 3a132ea has been approved by cuviper

[Centril]

Failed in #61032 (comment), @bors r-

[alexcrichton]

Looks like our old friend rust-lang/compiler-rt@d85fb9e never made its way into the llvm-project submodule (and for good reason!). I've now applied it and included it here.

@bors: r=cuviper

[bors]

📌 Commit e59f0cc has been approved by cuviper