[LLVMdev] Coverage mapping issue: Malformed profile data

[Dmitry Volyntsev]

Hi all!

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.

Also, as I can track down the problem raised because of
lib/ProfileData/CoverageMappingReader.cpp (SectionData::get) expects
that function's names located inside __llvm_prf_names section but it
not true in case of test1.c, instead some function names located
inside .rodata section.


Is it known issue?
any hints, how to avoid or workaround it?

-- 
Be happy,
Best regards,
Dmitry Volyntsev