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re PR c++/11773 (GCOV misreports coverage for in-class C++ member functions)

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PR c++/11773
	* doc/gcov.texi (Gcov and Optimization): Document inline function
	behaviour.  Fix some file suffixes.

From-SVN: r74630
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Nathan Sidwell 2003-12-15 14:29:10 +00:00 committed by Nathan Sidwell
parent f5c28a158b
commit 58cd2515ae
2 changed files with 33 additions and 5 deletions
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gcc/ChangeLog
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@ -1,3 +1,9 @@
2003-12-15 Nathan Sidwell <nathan@codesourcery.com>
PR c++/11773
* doc/gcov.texi (Gcov and Optimization): Document inline function
behaviour. Fix some file suffixes.
2003-12-14 David O'Brien <obrien@FreeBSD.org>
* config/i386/i386.h (__amd64, __amd64__): Remove duplicates.

32
gcc/doc/gcov.texi
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@ -249,8 +249,8 @@ information needed by gcov. These additional files are placed in the
directory where the object file is located.
Running the program will cause profile output to be generated. For each
source file compiled with @option{-fprofile-arcs}, an accompanying @file{.da}
file will be placed in the object file directory.
source file compiled with @option{-fprofile-arcs}, an accompanying
@file{.gcda} file will be placed in the object file directory.
Running @command{gcov} with your program's source file names as arguments
will now produce a listing of the code along with frequency of execution
@ -410,7 +410,7 @@ of times the call was executed will be printed. This will usually be
and thus may not return every time they are called.
The execution counts are cumulative. If the example program were
executed again without removing the @file{.da} file, the count for the
executed again without removing the @file{.gcda} file, the count for the
number of times each line in the source was executed would be added to
the results of the previous run(s). This is potentially useful in
several ways. For example, it could be used to accumulate data over a
@ -418,9 +418,9 @@ number of program runs as part of a test verification suite, or to
provide more accurate long-term information over a large number of
program runs.
The data in the @file{.da} files is saved immediately before the program
The data in the @file{.gcda} files is saved immediately before the program
exits. For each source file compiled with @option{-fprofile-arcs}, the
profiling code first attempts to read in an existing @file{.da} file; if
profiling code first attempts to read in an existing @file{.gcda} file; if
the file doesn't match the executable (differing number of basic block
counts) it will ignore the contents of the file. It then adds in the
new execution counts and finally writes the data to the file.
@ -463,6 +463,28 @@ executed 100 times. In one sense this result is correct, because there
was only one instruction representing all four of these lines. However,
the output does not indicate how many times the result was 0 and how
many times the result was 1.
Inlineable functions can create unexpected line counts. Line counts are
shown for the source code of the inlineable function, but what is shown
depends on where the function is inlined, or if it is not inlined at all.
If the function is not inlined, the compiler must emit an out of line
copy of the function, in any object file that needs it. If
@file{fileA.o} and @file{fileB.o} both contain out of line bodies of a
particular inlineable function, they will also both contain coverage
counts for that function. When @file{fileA.o} and @file{fileB.o} are
linked together, the linker will, on many systems, select one of those
out of line bodies for all calls to that function, and remove or ignore
the other. Unfortunately, it will not remove the coverage counters for
the unused function body. Hence when instrumented, all but one use of
that function will show zero counts.
If the function is inlined in several places, the block structure in
each location might not be the same. For instance, a condition might
now be calculable at compile time in some instances. Because the
coverage of all the uses of the inline function will be shown for the
same source lines, the line counts themselves might seem inconsistent.
@c man end
@node Gcov Data Files