maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/test/Instrumentation/InstrProfiling/comdat.ll

Ignoring revisions in .git-blame-ignore-revs. Click here to bypass and see the normal blame view.

39 lines
2.2 KiB
LLVM
Raw Normal View History

[InstrProf] Implement static profdata registration Summary: The motivating use case is eliminating duplicate profile data registered for the same inline function in two object files. Before this change, users would observe multiple symbol definition errors with VC link, but links with LLD would succeed. Users (Mozilla) have reported that PGO works well with clang-cl and LLD, but when using LLD without this static registration, we would get into a "relocation against a discarded section" situation. I'm not sure what happens in that situation, but I suspect that duplicate, unused profile information was retained. If so, this change will reduce the size of such binaries with LLD. Now, Windows uses static registration and is in line with all the other platforms. Reviewers: davidxl, wmi, inglorion, void, calixte Subscribers: mgorny, krytarowski, eraman, fedor.sergeev, hiraditya, #sanitizers, dmajor, llvm-commits Tags: #sanitizers, #llvm Differential Revision: https://reviews.llvm.org/D57929 llvm-svn: 353547
2019-02-09 03:03:50 +08:00
; RUN: opt < %s -mtriple=x86_64-unknown-linux -instrprof -S | FileCheck %s --check-prefixes=ELF
; RUN: opt < %s -mtriple=x86_64-pc-win32-coff -instrprof -S | FileCheck %s --check-prefixes=COFF
; RUN: opt < %s -mtriple=x86_64-unknown-linux -passes=instrprof -S | FileCheck %s --check-prefixes=ELF
; RUN: opt < %s -mtriple=x86_64-pc-win32-coff -passes=instrprof -S | FileCheck %s --check-prefixes=COFF
; There are two main cases where comdats are necessary:
; 1. standard inline functions (weak_odr / linkonce_odr)
; 2. available externally functions (C99 inline / extern template / dllimport)
; Check that we do the right thing for the two object formats with comdats, ELF
; and COFF.
declare void @llvm.instrprof.increment(i8*, i64, i32, i32)
$foo_inline = comdat any
@__profn_foo_inline = linkonce_odr hidden constant [10 x i8] c"foo_inline"
[PGO] Move __profc_ and __profvp_ from their own comdat groups to __profd_'s comdat group D68041 placed `__profc_`, `__profd_` and (if exists) `__profvp_` in different comdat groups. There are some issues: * Cost: one or two additional section headers (`.group` section(s)): 64 or 128 bytes on ELF64. * `__profc_`, `__profd_` and (if exists) `__profvp_` should be retained or discarded. Placing them into separate comdat groups is conceptually inferior. * If the prevailing group does not include `__profvp_` (value profiling not used) but a non-prevailing group from another translation unit has `__profvp_` (the function is inlined into another and triggers value profiling), there will be a stray `__profvp_` if --gc-sections is not enabled. This has been fixed by 3d6f53018f845e893ad34f64ff2851a2e5c3ba1d. Actually, we can reuse an existing symbol (we choose `__profd_`) as the group signature to avoid a string in the string table (the sole reason that D68041 could improve code size is that `__profv_` was an otherwise unused symbol which wasted string table space). This saves one or two section headers. For a -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_INSTRUMENTED=IR build, `ninja clang lld`, the patch has saved 10.5MiB (2.2%) for the total .o size. Reviewed By: davidxl Differential Revision: https://reviews.llvm.org/D84723
2020-08-04 11:35:50 +08:00
; ELF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat($__profd_foo_inline), align 8
[PGO] Don't group COMDAT variables for compiler generated profile variables in ELF With this patch, compiler generated profile variables will have its own COMDAT name for ELF format, which syncs the behavior with COFF. Tested with clang PGO bootstrap. This shows a modest reduction in object sizes in ELF format. Differential Revision: https://reviews.llvm.org/D68041 llvm-svn: 373241
2019-10-01 02:11:22 +08:00
; ELF: @__profd_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_data", comdat, align 8
[PGO] Use multiple comdat groups for COFF D84723 caused multiple definition issues (related to comdat) on Windows: http://lab.llvm.org:8011/builders/sanitizer-windows/builds/67465
2020-08-04 12:32:44 +08:00
; COFF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat, align 8
[PGO] Don't use comdat groups for counters & data on COFF For COFF, a comdat group is really a symbol marked IMAGE_COMDAT_SELECT_ANY and zero or more other symbols marked IMAGE_COMDAT_SELECT_ASSOCIATIVE. Typically the associative symbols in the group are not external and are not referenced by other TUs, they are things like debug info, C++ dynamic initializers, or other section registration schemes. The Visual C++ linker reports a duplicate symbol error for symbols marked IMAGE_COMDAT_SELECT_ASSOCIATIVE even if they would be discarded after handling the leader symbol. Fixes coverage-inline.cpp in check-profile after r372020. llvm-svn: 372182
2019-09-18 05:10:49 +08:00
; COFF: @__profd_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfd$M", comdat, align 8
[InstrProf] Implement static profdata registration Summary: The motivating use case is eliminating duplicate profile data registered for the same inline function in two object files. Before this change, users would observe multiple symbol definition errors with VC link, but links with LLD would succeed. Users (Mozilla) have reported that PGO works well with clang-cl and LLD, but when using LLD without this static registration, we would get into a "relocation against a discarded section" situation. I'm not sure what happens in that situation, but I suspect that duplicate, unused profile information was retained. If so, this change will reduce the size of such binaries with LLD. Now, Windows uses static registration and is in line with all the other platforms. Reviewers: davidxl, wmi, inglorion, void, calixte Subscribers: mgorny, krytarowski, eraman, fedor.sergeev, hiraditya, #sanitizers, dmajor, llvm-commits Tags: #sanitizers, #llvm Differential Revision: https://reviews.llvm.org/D57929 llvm-svn: 353547
2019-02-09 03:03:50 +08:00
define weak_odr void @foo_inline() comdat {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_inline, i32 0, i32 0), i64 0, i32 1, i32 0)
ret void
}
$foo_extern = comdat any
@__profn_foo_extern = linkonce_odr hidden constant [10 x i8] c"foo_extern"
[PGO] Move __profc_ and __profvp_ from their own comdat groups to __profd_'s comdat group D68041 placed `__profc_`, `__profd_` and (if exists) `__profvp_` in different comdat groups. There are some issues: * Cost: one or two additional section headers (`.group` section(s)): 64 or 128 bytes on ELF64. * `__profc_`, `__profd_` and (if exists) `__profvp_` should be retained or discarded. Placing them into separate comdat groups is conceptually inferior. * If the prevailing group does not include `__profvp_` (value profiling not used) but a non-prevailing group from another translation unit has `__profvp_` (the function is inlined into another and triggers value profiling), there will be a stray `__profvp_` if --gc-sections is not enabled. This has been fixed by 3d6f53018f845e893ad34f64ff2851a2e5c3ba1d. Actually, we can reuse an existing symbol (we choose `__profd_`) as the group signature to avoid a string in the string table (the sole reason that D68041 could improve code size is that `__profv_` was an otherwise unused symbol which wasted string table space). This saves one or two section headers. For a -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_INSTRUMENTED=IR build, `ninja clang lld`, the patch has saved 10.5MiB (2.2%) for the total .o size. Reviewed By: davidxl Differential Revision: https://reviews.llvm.org/D84723
2020-08-04 11:35:50 +08:00
; ELF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat($__profd_foo_extern), align 8
[PGO] Don't group COMDAT variables for compiler generated profile variables in ELF With this patch, compiler generated profile variables will have its own COMDAT name for ELF format, which syncs the behavior with COFF. Tested with clang PGO bootstrap. This shows a modest reduction in object sizes in ELF format. Differential Revision: https://reviews.llvm.org/D68041 llvm-svn: 373241
2019-10-01 02:11:22 +08:00
; ELF: @__profd_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_data", comdat, align 8
[PGO] Use multiple comdat groups for COFF D84723 caused multiple definition issues (related to comdat) on Windows: http://lab.llvm.org:8011/builders/sanitizer-windows/builds/67465
2020-08-04 12:32:44 +08:00
; COFF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat, align 8
[PGO] Don't use comdat groups for counters & data on COFF For COFF, a comdat group is really a symbol marked IMAGE_COMDAT_SELECT_ANY and zero or more other symbols marked IMAGE_COMDAT_SELECT_ASSOCIATIVE. Typically the associative symbols in the group are not external and are not referenced by other TUs, they are things like debug info, C++ dynamic initializers, or other section registration schemes. The Visual C++ linker reports a duplicate symbol error for symbols marked IMAGE_COMDAT_SELECT_ASSOCIATIVE even if they would be discarded after handling the leader symbol. Fixes coverage-inline.cpp in check-profile after r372020. llvm-svn: 372182
2019-09-18 05:10:49 +08:00
; COFF: @__profd_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfd$M", comdat, align 8
[InstrProf] Implement static profdata registration Summary: The motivating use case is eliminating duplicate profile data registered for the same inline function in two object files. Before this change, users would observe multiple symbol definition errors with VC link, but links with LLD would succeed. Users (Mozilla) have reported that PGO works well with clang-cl and LLD, but when using LLD without this static registration, we would get into a "relocation against a discarded section" situation. I'm not sure what happens in that situation, but I suspect that duplicate, unused profile information was retained. If so, this change will reduce the size of such binaries with LLD. Now, Windows uses static registration and is in line with all the other platforms. Reviewers: davidxl, wmi, inglorion, void, calixte Subscribers: mgorny, krytarowski, eraman, fedor.sergeev, hiraditya, #sanitizers, dmajor, llvm-commits Tags: #sanitizers, #llvm Differential Revision: https://reviews.llvm.org/D57929 llvm-svn: 353547
2019-02-09 03:03:50 +08:00
define available_externally void @foo_extern() {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_extern, i32 0, i32 0), i64 0, i32 1, i32 0)
ret void
}