Commit Graph

5 Commits

Author SHA1 Message Date
Fangrui Song fd739804e0 [test] Add {{.*}} to make ELF tests immune to dso_local/dso_preemptable/(none) differences
For a default visibility external linkage definition, dso_local is set for ELF
-fno-pic/-fpie and COFF and Mach-O. Since default clang -cc1 for ELF is similar
to -fpic ("PIC Level" is not set), this nuance causes unneeded binary format differences.

To make emitted IR similar, ELF -cc1 -fpic will default to -fno-semantic-interposition,
which sets dso_local for default visibility external linkage definitions.

To make this flip smooth and enable future (dso_local as definition default),
this patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `.
2020-12-31 00:27:11 -08:00
Fangrui Song dbc96b518b Revert "[CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition"
This reverts commit 789a46f2d7.

Accidentally committed.
2020-02-03 10:09:39 -08:00
Fangrui Song 789a46f2d7 [CodeGenModule] Assume dso_local for -fpic -fno-semantic-interposition
Summary:
Clang -fpic defaults to -fno-semantic-interposition (GCC -fpic defaults
to -fsemantic-interposition).
Users need to specify -fsemantic-interposition to get semantic
interposition behavior.

Semantic interposition is currently a best-effort feature. There may
still be some cases where it is not handled well.

Reviewers: peter.smith, rnk, serge-sans-paille, sfertile, jfb, jdoerfert

Subscribers: dschuff, jyknight, dylanmckay, nemanjai, jvesely, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, arphaman, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73865
2020-02-03 09:52:48 -08:00
Fangrui Song d600ab3bb5 [Frontend] Delete some unneeded CC1 options 2020-01-23 22:01:04 -08:00
Dean Michael Berris 05cf443463 [XRay][clang] Emit "never-instrument" attribute
Summary:
Before this change, we only emit the XRay attributes in LLVM IR when the
-fxray-instrument flag is provided. This may cause issues with thinlto
when the final binary is being built/linked with -fxray-instrument, and
the constitutent LLVM IR gets re-lowered with xray instrumentation.

With this change, we can honour the "never-instrument "attributes
provided in the source code and preserve those in the IR. This way, even
in thinlto builds, we retain the attributes which say whether functions
should never be XRay instrumented.

This change addresses llvm.org/PR38922.

Reviewers: mboerger, eizan

Subscribers: mehdi_amini, dexonsmith, cfe-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D52015

llvm-svn: 342200
2018-09-14 01:59:12 +00:00