https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80629
Bug ID: 80629
Summary: Missing .loc for a function in the presence of -O2
Product: gcc
Version: 7.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: matt at godbolt dot org
Target Milestone: ---
Firstly; I appreciate how tricky it is to keep track of debug information in
the presence of optimization and inlining, but I wonder if there's something
specific happening in this case. This is filed against 7.1, but previous
versions had slightly different, but similar issues.
In the following code snippet:
---cut---
#include <memory>
int callByValue(std::unique_ptr<int> a) { return *a; } // comment me out - see
below
int callByRef(std::unique_ptr<int> && a) { return *a; }
int callItByRef(std::unique_ptr<int> a) {
return callByRef(std::move(a));
}
---cut---
Compiled and output thus:
g++ foo.cc -O2 -S -o - -g | c++filt | head -50
One can see that the final function "callItByRef" doesn't have a `.loc`
anywhere in it to tie it to the source.
At -O1 the locations are output correctly.
Interestingly, commenting out the (unused) callByValue function causes the
callItByRef to gain debug information, which makes me wonder if there's a bug
here rather than a difficulty in tracking debug information per se.
