caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[BOLT][NFCI] Use heuristic for matching split global functions (#90429)

Browse Source 
This change speeds up fragment matching for large BOLTed binaries where
all fragments of global parent functions are put under `bolt-pseudo.o`
file symbol:
- before: iterating over symbols under `bolt-pseudo.o` only to fail
  to find a parent,
- after: bail out immediately and use a global parent by name.

Test Plan: NFC, updated register-fragments-bolt-symbols.s
This commit is contained in:
Amir Ayupov
2025-06-20 12:46:56 -07:00
committed by GitHub
parent 6d8c6ef90c
commit 4959e8a1da
2 changed files with 12 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
bolt/lib/Rewrite/RewriteInstance.cpp
View File

@@ -1567,6 +1567,11 @@ void RewriteInstance::registerFragments() {
uint64_t ParentAddress{0};
// Check if containing FILE symbol is BOLT emitted synthetic symbol marking
// local fragments of global parents.
if (cantFail(FSI[-1].getName()) == getBOLTFileSymbolName())
goto registerParent;
// BOLT split fragment symbols are emitted just before the main function
// symbol.
for (ELFSymbolRef NextSymbol = Symbol; NextSymbol < StopSymbol;

7
bolt/test/X86/register-fragments-bolt-symbols.s
View File

@@ -29,6 +29,7 @@
# RUN: link_fdata %s %t.bolt %t.preagg PREAGG
# PREAGG: B X:0 #chain.cold.0# 1 0
# PREAGG: B X:0 #dummy# 1 0
# RUN: perf2bolt %t.bolt -p %t.preagg --pa -o %t.bat.fdata -w %t.bat.yaml -v=1 \
# RUN: | FileCheck %s --check-prefix=CHECK-REGISTER
# RUN: FileCheck --input-file %t.bat.fdata --check-prefix=CHECK-FDATA %s
@@ -44,7 +45,13 @@
# CHECK-SYMS: l F .text.cold [[#]] chain.cold.0
# CHECK-SYMS: l F .text [[#]] chain
# CHECK-SYMS: l df *ABS* [[#]] bolt-pseudo.o
# CHECK-SYMS: l F .text.cold [[#]] dummy.cold.0
# CHECK-SYMS: l F .text.cold.1 [[#]] dummy.cold.1
# CHECK-SYMS: l F .text.cold.2 [[#]] dummy.cold.2
# CHECK-REGISTER: BOLT-INFO: marking dummy.cold.0/1(*2) as a fragment of dummy
# CHECK-REGISTER: BOLT-INFO: marking dummy.cold.1/1(*2) as a fragment of dummy
# CHECK-REGISTER: BOLT-INFO: marking dummy.cold.2/1(*2) as a fragment of dummy
# CHECK-REGISTER: BOLT-INFO: marking chain.cold.0/1(*2) as a fragment of chain/2(*2)
# CHECK-FDATA: 0 [unknown] 0 1 chain/chain.s/2 10 0 1