Go programs assume that they can always find the location that called
them, via standard library functions like
http://golang.org/pkg/runtime/#Caller . In gccgo this is implemented
via libbacktrace, which uses debug info. This means that many Go
programs only works correctly if compiled with -g. As suggested in PR
64595, this patch changes the gccgo driver to turn on -g1 by default.
You can still use -g0 to disable debug info generation, or of course
you can strip the binary. Bootstrapped and ran Go testsuite on
x86_64-unknown-linux-gnu. Committed to mainline.
Ian
2015-01-23 Ian Lance Taylor <[email protected]>
PR go/64595
* go-lang.c (go_langhook_init_options_struct): Set default
debug_info_level.
(go_langhook_post_options): If debug_info_level is still the
default, make sure write_symbols is set.
* gccgo.texi (Invoking gccgo): Document that -g1 is the default.
Index: gcc/go/gccgo.texi
===================================================================
--- gcc/go/gccgo.texi (revision 219876)
+++ gcc/go/gccgo.texi (working copy)
@@ -223,6 +223,18 @@ may be used. Or the checks may be remov
@option{-fno-go-check-divide-overflow}. This option is currently on
by default, but in the future may be off by default on systems that do
not require it.
+
+@item -g
+@cindex @option{-g for gccgo}
+This is the standard @command{gcc} option (@pxref{Debugging Options, ,
+Debugging Options, gcc, Using the GNU Compiler Collection (GCC)}). It
+is mentioned here because by default @command{gccgo} turns on
+debugging information generation with the equivalent of the standard
+option @option{-g1}. This is because Go programs require debugging
+information to be available in order to get backtrace information. An
+explicit @option{-g0} may be used to disable the generation of
+debugging information, in which case certain standard library
+functions, such as @code{runtime.Callers}, will not operate correctly.
@end table
@c man end
Index: gcc/go/go-lang.c
===================================================================
--- gcc/go/go-lang.c (revision 219876)
+++ gcc/go/go-lang.c (working copy)
@@ -171,6 +171,12 @@ go_langhook_init_options_struct (struct
/* Exceptions are used to handle recovering from panics. */
opts->x_flag_exceptions = 1;
opts->x_flag_non_call_exceptions = 1;
+
+ /* Go programs expect runtime.Callers to work, and that uses
+ libbacktrace that uses debug info. Set the debug info level to 1
+ by default. In post_options we will set the debug type if the
+ debug info level was not set back to 0 on the command line. */
+ opts->x_debug_info_level = DINFO_LEVEL_TERSE;
}
/* Infrastructure for a vector of char * pointers. */
@@ -289,6 +295,12 @@ go_langhook_post_options (const char **p
if (!global_options_set.x_flag_optimize_sibling_calls)
global_options.x_flag_optimize_sibling_calls = 0;
+ /* If the debug info level is still 1, as set in init_options, make
+ sure that some debugging type is selected. */
+ if (global_options.x_debug_info_level == DINFO_LEVEL_TERSE
+ && global_options.x_write_symbols == NO_DEBUG)
+ global_options.x_write_symbols = PREFERRED_DEBUGGING_TYPE;
+
/* Returning false means that the backend should be used. */
return false;
}
