[LLVMdev] Coverage mapping issue: Malformed profile data (original) (raw)

Dmitry Volyntsev xeioexception at gmail.com
Tue Feb 10 10:55:03 PST 2015

Here is the bug: http://llvm.org/bugs/show_bug.cgi?id=22531

On Tue, Feb 10, 2015 at 7:47 PM, Justin Bogner <mail at justinbogner.com> wrote:

Dmitry Volyntsev <xeioexception at gmail.com> writes:

It seems I came across on issue with coverage mapping (http://www.llvm.org/docs/CoverageMappingFormat.html)

check on: llvm revision: r228136 clang Last Changed Rev: 228121 build: Debug+Asserts OS: ubuntu 14.04

Here is simple snippets test1.c: NOT OK ================== #include <stdio.h> static int foo() { return 42; } int main() { return 0; } ================== cp src/test1.c src/test.c; rm -fr default.profraw test.profdata ; clang -c -o obj/test.o src/test.c -I -g -O0 -fprofile-instr-generate -fcoverage-mapping; clang -o bin/test obj/test.o -I -g -O0 -fprofile-instr-generate -fcoverage-mapping; ./bin/test ; llvm-profdata merge -o test.profdata default.profraw; llvm-cov show ./bin/test -instr-profile=test.profdata error: Failed to load coverage: Malformed profile data

test2.c: OK ================== #include <stdio.h> static int foo() { return 42; } int main() { return foo(); } ================== cp src/test2.c src/test.c; rm -fr default.profraw test.profdata ; clang -c -o obj/test.o src/test.c -I -g -O0 -fprofile-instr-generate -fcoverage-mapping; clang -o bin/test obj/test.o -I -g -O0 -fprofile-instr-generate -fcoverage-mapping; ./bin/test ; llvm-profdata merge -o test.profdata default.profraw; llvm-cov show ./bin/test -instr-profile=test.profdata /home/xeioex/workspace/clang/experiments/llvm-cov/test/src/test.c: | 1|#include <stdio.h> | 2| 1| 3|static int foo() { return 42; } 1| 4|int main() { 1| 5| return foo(); 1| 6|} test3.c: OK ================== #include <stdio.h> int foo() { return 42; } int main() { return 0; } ================== cp src/test3.c src/test.c; rm -fr default.profraw test.profdata ; clang -c -o obj/test.o src/test.c -I -g -O0 -fprofile-instr-generate -fcoverage-mapping; clang -o bin/test obj/test.o -I -g -O0 -fprofile-instr-generate -fcoverage-mapping; ./bin/test ; llvm-profdata merge -o test.profdata default.profraw; llvm-cov show ./bin/test -instr-profile=test.profdata /home/xeioex/workspace/clang/experiments/llvm-cov/test/src/test.c: | 1|#include <stdio.h> | 2| 0| 3|int foo() { return 42; } 1| 4|int main() { 1| 5| return 0; 1| 6|} As far I can understand issue somehow related to unused static functions. It looks like this hits when a function isn't emitted by the frontend but we emit an "empty" coverage map for it. Also, as I can track down the problem raised because of lib/ProfileData/CoverageMappingReader.cpp (SectionData::get) expects _that function's names located inside llvmprfnames section but it not true in case of test1.c, instead some function names located inside .rodata section. The problem is that these don't go through the InstrProfiling machinery, so the names aren't lowered properly. I'd noticed a related issue not long ago, but fixed a bug by inspection that happened to hide it (r226764). Feel free to file a bug (http://llvm.org/bugs/) and I'll to get this fixed in the next day or two.

-- Be happy, Best regards, Dmitry Volyntsev

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