Closed andrjohns closed 1 month ago
And we still get the right TBB being linked in on macOS? The flag was introduced on Linux to enforce that no system defaults lead to link against a system TBB rather than the supplied TBB by Stan.
And we still get the right TBB being linked in on macOS? The flag was introduced on Linux to enforce that no system defaults lead to link against a system TBB rather than the supplied TBB by Stan.
The flag is only used when the TBB_LIB
variable is set - and a system TBB is being linked against
Great!
We've actually been patching this out in the conda build for some time, I've just continuously forgotten to upstream it: https://github.com/conda-forge/cmdstan-feedstock/blob/main/recipe/no-dtag-flag.patch
Peak downstream behaviour
Name | Old Result | New Result | Ratio | Performance change( 1 - new / old ) |
---|---|---|---|---|
arma/arma.stan | 0.19 | 0.2 | 0.94 | -5.92% slower |
low_dim_corr_gauss/low_dim_corr_gauss.stan | 0.01 | 0.01 | 1.07 | 6.56% faster |
gp_regr/gen_gp_data.stan | 0.02 | 0.02 | 1.05 | 4.43% faster |
gp_regr/gp_regr.stan | 0.11 | 0.11 | 1.01 | 0.53% faster |
sir/sir.stan | 83.13 | 84.21 | 0.99 | -1.3% slower |
irt_2pl/irt_2pl.stan | 4.04 | 4.0 | 1.01 | 0.8% faster |
eight_schools/eight_schools.stan | 0.06 | 0.05 | 1.01 | 1.28% faster |
pkpd/sim_one_comp_mm_elim_abs.stan | 0.25 | 0.26 | 0.99 | -0.93% slower |
pkpd/one_comp_mm_elim_abs.stan | 18.66 | 19.73 | 0.95 | -5.74% slower |
garch/garch.stan | 0.52 | 0.43 | 1.2 | 16.89% faster |
low_dim_gauss_mix/low_dim_gauss_mix.stan | 2.94 | 2.99 | 0.98 | -1.7% slower |
arK/arK.stan | 1.76 | 1.58 | 1.11 | 10.09% faster |
gp_pois_regr/gp_pois_regr.stan | 2.71 | 2.52 | 1.07 | 6.77% faster |
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan | 9.77 | 8.96 | 1.09 | 8.3% faster |
performance.compilation | 190.04 | 189.86 | 1.0 | 0.1% faster |
Mean result: 1.0315659926708851
Jenkins Console Log Blue Ocean Commit hash: 24717e4befa79396a1c98440805cce73129090b6
This change broke a build I had that was manually setting LDFLAGS_TBB
, since now the dtags flag is +='d it doesn't respect previous settings the way ?=
does.
The build in question is not on a Mac, but does use clang's lld. We don't really have a good way of detecting this automatically.
I also noticed this flag is only actually being passed if you are using a custom TBB, not one vendored by Stan, so I wonder why we even need it at all?
This change broke a build I had that was manually setting LDFLAGS_TBB, since now the dtags flag is +='d it doesn't respect previous settings the way ?= does.
A that makes sense, we could just wrap the +=
in an ifeq ($(LDFLAGS_TBB),)
?
I also noticed this flag is only actually being passed if you are using a custom TBB, not one vendored by Stan, so I wonder why we even need it at all?
Because if you try to use a custom TBB with Stan on Macos then you can't build the math library/cmdstan at all - because macos doesn't support the flag
Because if you try to use a custom TBB with Stan on Macos then you can't build the math library/cmdstan at all - because macos doesn't support the flag
I meant "why do we need --disable-new-dtags
on any platform". Like what about our vendored TBB means we don't need it on linux etc, but a user-supplied ones means we do?
Ah sorry, I thought you were asking why we needed the change.
I don't know enough about the TBB & linking or what the flag does, but @wds15 mentioned above that it was used to stop Stan from unintentionally linking to the wrong TBB
I think we can get nice, customizable behavior with
# MacOS ld does not support --disable-new-dtags
ifneq ($(OS),Darwin)
LDFLAGS_TBB_DTAGS ?= -Wl,--disable-new-dtags
endif
# Windows LLVM/Clang does not support -rpath, but is not needed on Windows anyway
ifneq ($(OS), Windows_NT)
LDFLAGS_TBB_RPATH ?= -Wl,-rpath,"$(TBB_LIB)"
endif
LDFLAGS_TBB ?= -Wl,-L,"$(TBB_LIB)" $(LDFLAGS_TBB_DTAGS) $(LDFLAGS_TBB_RPATH)
Summary
While helping a user specify the Homebrew TBB for use with CmdStan, I discovered that the linker on macos doesn't support the
-Wl,--disable-new-dtags
argument:It's not an issue with the Linux clang though (checked in a Debian Sid docker image)
Tests
N/A
Side Effects
N/A
Release notes
Fix linker error when using external TBB on MacOS
Checklist
[x] Copyright holder: Andrew Johnson
The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the license the submitted work under the following licenses:
[x] the basic tests are passing
./runTests.py test/unit
)make test-headers
)make test-math-dependencies
)make doxygen
)make cpplint
)[x] the code is written in idiomatic C++ and changes are documented in the doxygen
[x] the new changes are tested