zequanwu added a comment.
> It seems that the `__llvm_prf_names` is retained in this mode. What is the
> overhead of this section generally? Can we instead use debug info to lookup
> function names?
With debug info correlation enabled, `__llvm_prf_names` section will only
contain functions names that are not emitted to the final binary, not even in
debug info. So, this section is still much smaller compared to when not
enabling debug info correlation. This is used to indicate that those functions
are covered but not executed.
Example from the test case above:
$ cat a.cpp
struct A {
void unused_func() {}
};
void used_func() {}
int main() {
used_func();
return 0;
}
$ clang -fprofile-instr-generate -fcoverage-mapping -mllvm
-enable-name-compression=false -mllvm -debug-info-correlate -g a.cpp -o a.out
$ llvm-objdump --section=__llvm_prf_names --full-contents a.out
a.out: file format elf64-x86-64
Contents of section __llvm_prf_names:
7b65 14005f5a 4e314131 31756e75 7365645f .._ZN1A11unused_
7b75 66756e63 4576 funcEv
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D157913/new/
https://reviews.llvm.org/D157913
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