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[BOLT] Allow empty buildid in pre-aggregated profile addresses (#190675)

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Allow `parseString()` to return an empty `StringRef` when the delimiter
appears at position 0. This enables parsing pre-aggregated profile
addresses with an omitted buildid but preserved colon (`:addr` format),
where the empty buildid corresponds to the main binary.

Previously, `parseString()` rejected zero-length fields by treating
`StringEnd == 0` the same as `StringRef::npos` (delimiter not found).
These are distinct situations: `npos` means no delimiter exists, while
`0` means the field before the delimiter is empty. The fix removes the
`StringEnd == 0` sub-condition so only the missing-delimiter case
errors.

The existing test for buildid-prefixed addresses is extended to also
verify that `:addr` input produces identical output to the plain-address
and non-empty-buildid variants.

Test Plan:
Added empty-buildid input file and extended
`pre-aggregated-perf-buildid.test` to run perf2bolt with `:addr` format
and diff the fdata output against the existing buildid-prefixed result.
This commit is contained in:
Amir Ayupov 2026-04-06 14:41:21 -07:00 committed by GitHub
parent 79e669f000
commit a8cf1a0352
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
3 changed files with 18 additions and 2 deletions
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3
bolt/lib/Profile/DataReader.cpp
View File

@ -834,8 +834,7 @@ ErrorOr<StringRef> DataReader::parseString(char EndChar, bool EndNl) {
size_t StringEnd = 0;
do {
StringEnd = ParsingBuf.find_first_of(EndChars, StringEnd);
if (StringEnd == StringRef::npos ||
(StringEnd == 0 && ParsingBuf[StringEnd] != '\\')) {
if (StringEnd == StringRef::npos) {
reportError("malformed field");
return make_error_code(llvm::errc::io_error);
}

9
bolt/test/X86/Inputs/pre-aggregated-buildid-empty.txt Normal file
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@ -0,0 +1,9 @@
B deadbeefaabbccdd:7f36d18d60c0 :400bbc 2 0
B :400ad1 :400e00 2 0
B :400b10 :4005f0 1 0
B :400bb7 :400610 1 0
B :4005f0 cafebabe01234567:7f36d18f2ce0 1 0
B :4011a0 :4011a9 33 4
B :4011ad :401180 58 0
F :401170 :4011b2 22
B :400dae :400d90 1 0

8
bolt/test/X86/pre-aggregated-perf-buildid.test
View File

@ -30,6 +30,14 @@ CHECK-FDATA: 1 usqrt 35 1 usqrt 39 0 22
CHECK-FDATA: 1 usqrt 3d 1 usqrt 10 0 58
CHECK-FDATA: 1 usqrt 3d 1 usqrt 3f 0 22
## Test with empty buildid prefix on main binary addresses (`:addr` format).
## An omitted buildid with a preserved colon should be treated as the main
## binary. The output should be identical to the non-empty buildid version.
RUN: perf2bolt %t.exe -o %t.fdata2 --pa \
RUN: -p %p/Inputs/pre-aggregated-buildid-empty.txt \
RUN: --profile-format=fdata 2>&1 | FileCheck %s --check-prefix=CHECK-BUILDID
RUN: diff %t.fdata %t.fdata2
## Test YAML output with buildid-prefixed input.
RUN: perf2bolt %t.exe -o %t.yaml --pa -p %p/Inputs/pre-aggregated-buildid.txt \
RUN: --profile-format=yaml --profile-use-dfs 2>&1