Skip to content

[BOLT] Skip FDE emission for patch functions #136224

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Apr 18, 2025
Merged

[BOLT] Skip FDE emission for patch functions #136224

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
2316b4f
[BOLT] Skip FDE emission for patch functions
maksfb Apr 17, 2025
48fb627
fixup! [BOLT] Skip FDE emission for patch functions
maksfb Apr 18, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 4 additions & 2 deletions bolt/lib/Core/BinaryEmitter.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -373,8 +373,10 @@ bool BinaryEmitter::emitFunction(BinaryFunction &Function,
Streamer.emitLabel(StartSymbol);
}

const bool NeedsFDE =
Function.hasCFI() && !(Function.isPatch() && Function.isAnonymous());
// Emit CFI start
if (Function.hasCFI()) {
if (NeedsFDE) {
Streamer.emitCFIStartProc(/*IsSimple=*/false);
if (Function.getPersonalityFunction() != nullptr)
Streamer.emitCFIPersonality(Function.getPersonalityFunction(),
Expand Down Expand Up @@ -421,7 +423,7 @@ bool BinaryEmitter::emitFunction(BinaryFunction &Function,
Streamer.emitBytes(BC.MIB->getTrapFillValue());

// Emit CFI end
if (Function.hasCFI())
if (NeedsFDE)
Streamer.emitCFIEndProc();

MCSymbol *EndSymbol = Function.getFunctionEndLabel(FF.getFragmentNum());
Expand Down
7 changes: 7 additions & 0 deletions bolt/test/AArch64/lite-mode.s
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,13 @@
# RUN: llvm-objdump -d --disassemble-symbols=cold_function %t.bolt \
# RUN: | FileCheck %s


## Verify that the number of FDEs matches the number of functions in the output
## binary. There are three original functions and two optimized.
# RUN: llvm-readelf -u %t.bolt | grep -wc FDE \
# RUN: | FileCheck --check-prefix=CHECK-FDE %s
# CHECK-FDE: 5

## In lite mode, optimized code will be separated from the original .text by
## over 128MB, making it impossible for call/bl instructions in cold functions
## to reach optimized functions directly.
Expand Down
Loading