Cold-Air-Networks/mirror-llvm-project
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 7

[MC] Emit Mach-O pseudo-probe sections in the __LLVM segment (#206793)

Browse source 
Let's back this out in favor of emitting pseudoprobe data in favor of
emitting in the __LLVM segment, and let dsymutil collect the debug map
objects and merge them into the final sections.

This is to prevent older ld toolchains that don't ignore the new
`__PSEUDO_PROBE` segments from accidentally leaking the probe metadata
into the final image.
This commit is contained in:
Henry Jiang 2026-07-21 14:27:22 -07:00 committed by GitHub
parent 866832a596
commit e55d3bca36
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
2 changed files with 12 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
llvm/lib/MC/MCObjectFileInfo.cpp
View file

@ -322,12 +322,14 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(const Triple &T) {
RemarksSection = Ctx->getMachOSection(
"__LLVM", "__remarks", MachO::S_ATTR_DEBUG, SectionKind::getMetadata());
PseudoProbeSection =
Ctx->getMachOSection("__PSEUDO_PROBE", "__probes",
MachO::S_ATTR_DEBUG | MachO::S_ATTR_NO_DEAD_STRIP,
SectionKind::getMetadata());
// Emit the pseudoprobe sections in the __LLVM segment. Current ld ignores the
// __LLVM and __DWARF segment, so the probe metadata is dropped from the final
// linked image on every toolchain.
PseudoProbeSection = Ctx->getMachOSection(
"__LLVM", "__probes", MachO::S_ATTR_DEBUG | MachO::S_ATTR_NO_DEAD_STRIP,
SectionKind::getMetadata());
PseudoProbeDescSection =
Ctx->getMachOSection("__PSEUDO_PROBE", "__probe_descs",
Ctx->getMachOSection("__LLVM", "__probe_descs",
MachO::S_ATTR_DEBUG | MachO::S_ATTR_NO_DEAD_STRIP,
SectionKind::getMetadata());

10
llvm/test/Transforms/SampleProfile/pseudo-probe-emit-macho.ll
View file

@ -83,7 +83,7 @@ entry:
; CHECK-IL: ![[#SCOPE1]] = !DILexicalBlockFile(scope: ![[#]], file: ![[#]], discriminator: 455082015)
; Check the generation of pseudo_probe_desc section for MachO
; CHECK-ASM-MACHO: .section __PSEUDO_PROBE,__probe_descs,regular,no_dead_strip+debug
; CHECK-ASM-MACHO: .section __LLVM,__probe_descs,regular,no_dead_strip+debug
; CHECK-ASM-MACHO-NEXT: .quad [[#GUID]]
; CHECK-ASM-MACHO-NEXT: .quad [[#HASH:]]
; CHECK-ASM-MACHO-NEXT: .byte 3
@ -95,24 +95,24 @@ entry:
; CHECK-SEC-MACHO-LABEL: Sections [
; CHECK-SEC-MACHO: Name: __probe_descs
; CHECK-SEC-MACHO-NEXT: Segment: __PSEUDO_PROBE
; CHECK-SEC-MACHO-NEXT: Segment: __LLVM
; CHECK-SEC-MACHO: Attributes [ (0x120000)
; CHECK-SEC-MACHO-NEXT: Debug (0x20000)
; CHECK-SEC-MACHO-NEXT: NoDeadStrip (0x100000)
; CHECK-SEC-MACHO: Name: __probes
; CHECK-SEC-MACHO-NEXT: Segment: __PSEUDO_PROBE
; CHECK-SEC-MACHO-NEXT: Segment: __LLVM
; CHECK-SEC-MACHO: Attributes [ (0x120000)
; CHECK-SEC-MACHO-NEXT: Debug (0x20000)
; CHECK-SEC-MACHO-NEXT: NoDeadStrip (0x100000)
; CHECK-SEC-MACHO-MC-LABEL: Sections [
; CHECK-SEC-MACHO-MC: Name: __probe_descs
; CHECK-SEC-MACHO-MC-NEXT: Segment: __PSEUDO_PROBE
; CHECK-SEC-MACHO-MC-NEXT: Segment: __LLVM
; CHECK-SEC-MACHO-MC: Attributes [ (0x120000)
; CHECK-SEC-MACHO-MC-NEXT: Debug (0x20000)
; CHECK-SEC-MACHO-MC-NEXT: NoDeadStrip (0x100000)
; CHECK-SEC-MACHO-MC: Name: __probes
; CHECK-SEC-MACHO-MC-NEXT: Segment: __PSEUDO_PROBE
; CHECK-SEC-MACHO-MC-NEXT: Segment: __LLVM
; CHECK-SEC-MACHO-MC: Attributes [ (0x120000)
; CHECK-SEC-MACHO-MC-NEXT: Debug (0x20000)
; CHECK-SEC-MACHO-MC-NEXT: NoDeadStrip (0x100000)