build: use `-no_exported_symbols` on macOS #29072

fanquake commented at 12:03 PM on December 13, 2023: member

This reduces the size of the binary by ~1% when building with --enable-reduce-exports.

-no_exported_symbols Useful for main executable that don't have plugins and thus need no symbol exports.

Can be tested with dyld_info -exports src/bitcoind. The only exported symbol should be __mh_execute_header.

DrahtBot commented at 12:03 PM on December 13, 2023: contributor

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DrahtBot added the label Build system on Dec 13, 2023

fanquake force-pushed on Dec 18, 2023

in configure.ac:1535 in 5f1113a2df outdated

1531 | @@ -1532,6 +1532,7 @@ if test "$use_reduce_exports" = "yes"; then
1532 |    AX_CHECK_COMPILE_FLAG([-fvisibility=hidden], [CORE_CXXFLAGS="$CORE_CXXFLAGS -fvisibility=hidden"],
1533 |    [AC_MSG_ERROR([Cannot set hidden symbol visibility. Use --disable-reduce-exports.])], [$CXXFLAG_WERROR])
1534 |    AX_CHECK_LINK_FLAG([-Wl,--exclude-libs,ALL], [RELDFLAGS="-Wl,--exclude-libs,ALL"], [], [$LDFLAG_WERROR])
1535 | +  AX_CHECK_LINK_FLAG([-Wl,-no_exported_symbols], [RELDFLAGS="$RELDFLAGS -Wl,-no_exported_symbols"], [], [$LDFLAG_WERROR])

hebasto commented at 3:25 PM on January 2, 2024:

This makes libbitcoinconsensus.0.dylib export no symbols, which is not what we want, right?

% dyld_info -exports src/.libs/libbitcoinconsensus.0.dylib        
src/.libs/libbitcoinconsensus.0.dylib [arm64]:
    -exports:
        offset      symbol

fanquake commented at 10:56 AM on February 27, 2024:

Moved this into LIBTOOL_APP_LDFLAGS.

DrahtBot added the label CI failed on Jan 16, 2024

fanquake force-pushed on Feb 27, 2024

DrahtBot removed the label CI failed on Feb 27, 2024

maflcko added the label DrahtBot Guix build requested on Apr 23, 2024

DrahtBot commented at 2:00 AM on April 24, 2024: contributor

Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]

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*.tar.gz	`605e4204e1262b8e...`	`fdda4cd1c750cacd...`
guix_build.log	`92253d3d25e61b0e...`	`7504c7d212dc2eb6...`
guix_build.log.diff		`65038b0618896e1b...`

DrahtBot removed the label DrahtBot Guix build requested on Apr 24, 2024

hebasto added the label Needs CMake port on Apr 24, 2024

fanquake force-pushed on May 10, 2024

fanquake commented at 1:32 PM on May 10, 2024: member

Based on #21778, so the flag is usable in release builds.

DrahtBot added the label Needs rebase on May 13, 2024

fanquake force-pushed on May 13, 2024

fanquake marked this as a draft on May 13, 2024

fanquake commented at 12:13 PM on May 13, 2024: member

Rebased, but drafted while based on #21778.

DrahtBot removed the label Needs rebase on May 13, 2024

fanquake force-pushed on May 29, 2024

fanquake marked this as ready for review on May 29, 2024

fanquake commented at 9:36 AM on May 29, 2024: member

Binary size comparison for arm64-apple-darwin of a Guix build of master (be100cf4c77a) vs this PR (6213ac97c6b5):

Binary	master	PR
bitcoin-cli	481248	477056
bitcoin-qt	30559072	30511316
bitcoin-tx	2246456	2245808
bitcoin-util	324200	324168
bitcoin-wallet	5091904	5054440
bitcoind	11867476	11820592
test_bitcoin	20097440	20054668

fanquake force-pushed on May 31, 2024

fanquake commented at 4:23 PM on May 31, 2024: member

@theuni do you have any thoughts here?

fanquake force-pushed on Jun 11, 2024

theuni commented at 3:49 PM on June 11, 2024: member

Does __attribute__ ((visibility ("default"))) override this? Otherwise I assume we'd need to make sure this flag doesn't make it to shared libs.

theuni commented at 3:51 PM on June 11, 2024: member

Does __attribute__ ((visibility ("default"))) override this? Otherwise I assume we'd need to make sure this flag doesn't make it to shared libs.

Oh whoops, already asked and answered. Nevermind!

build: use -no_exported_symbols on macOS

This reduces the size of the binary by 2-3% when building with
`--enable-reduce-exports`.

81d4dc8e87

fanquake force-pushed on Jun 18, 2024

fanquake commented at 12:30 PM on June 18, 2024: member

Guix Build (aarch64):

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DrahtBot added the label CI failed on Jun 18, 2024

DrahtBot removed the label CI failed on Jun 18, 2024

TheCharlatan commented at 4:14 PM on June 25, 2024: contributor

Guix build (aarch64):

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hebasto commented at 2:27 PM on July 16, 2024: member

Tested 81d4dc8e8739df0e9a8e92f55071733f6500617b on macOS 14.5 Sonoma (Apple Silicon):

the master branch @ 9c5cdf07f30f816cd134e2cd2dca9c27ef7067a5:

% nm --extern-only src/bitcoind | wc -l                                                    
     579

this PR:

% nm --extern-only src/bitcoind | wc -l     
     537

I don't know the reasons, but bitcoind still exports

0000000100000000 T __mh_execute_header

The new -no_exported_symbols linker flag is not printed in the configure summary.

fanquake commented at 2:29 PM on July 16, 2024: member

I don't know the reasons, but bitcoind still exports

That is expected. See the PR description.

The new -no_exported_symbols linker flag is not printed in the configure summary.

That's expected. We don't print the RE LD flags.

theuni approved

theuni commented at 2:33 PM on July 16, 2024: member

utACK 81d4dc8e8739df0e9a8e92f55071733f6500617b

hebasto approved

hebasto commented at 2:36 PM on July 16, 2024: member

ACK 81d4dc8e8739df0e9a8e92f55071733f6500617b.

The new -no_exported_symbols linker flag is not printed in the configure summary.

That's expected. We don't print the RE LD flags.

Not related to this PR changes, but that's odd as it undermines the summary's goal.

fanquake merged this on Jul 16, 2024

fanquake closed this on Jul 16, 2024

fanquake deleted the branch on Jul 16, 2024

hebasto commented at 9:57 PM on July 19, 2024: member

Ported to the CMake-based build system in https://github.com/hebasto/bitcoin/pull/271.

hebasto removed the label Needs CMake port on Jul 19, 2024

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