[PATCH] Make -Wcoverage-mismatch behavior sane.

[Neil Vachharajani <nvachhar at google dot com>]

By default, coverage mismatches are errors. ?Unlike every other -W
option, -Wcoverage-mismatch demotes the error to a warning (rather
than simply enabling the warning). ?Unfortunately, when compiling with
-Werror, this warning gets *re-promoted* to an error. ?There is a
difference between the original error (i.e., when compiling w/o
-Wcoverage-mismatch) and this new error (created by promoting a
warning to an error). ?-Wno-error=coverage-mismatch will prevent the
warning from being promoted to an error. ?So you need both options
(-Wcoverage-mismatch and -Wno-error=coverage-mismatch) to guarantee
that coverage mismatch's are only reported as warnings and not errors.

This patch changes the behavior so that -Wcoverage-mismatch enables
the coverage mismatch warnings. ?It is on by default and can be
negated (unlike before). ?To maintain the current behavior that
coverage mismatches are reported as errors, by default
-Werror=coverage-mismatch is also enabled. ?The warning can be
disabled with -Wno-coverage-mismatch and the error can be disabled
with -Wno-error=coverage-mismatch.
Bootstrapped and regtested on x86_64. ?Ok for trunk?

2010-04-28 ?Neil Vachharajani <nvachhar@google.com>

?? ? ? ?* doc/invoke.texi (-Wcoverage-mismatch): Updated documentation as
?? ? ? ?per new semantics.
?? ? ? ?* opts.c (decode_options): Enable -Werror=coverage-mismatch.
?? ? ? ?* coverage.c (get_coverage_counts): Always emit a warning. ?Adjust
?? ? ? ?conditions for printing notes.
?? ? ? ?* common.opt (-Wcoverage-mismatch): Allow negative, default to
?? ? ? ?true, update documentation.
?? ? ? ?* Makefile.in (coverage.o): Add dependence on DIAGNOSTIC_H.

diff --git a/gcc/gcc/Makefile.in b/gcc/gcc/Makefile.in
index ca68570..884d254 100644
--- a/gcc/gcc/Makefile.in
+++ b/gcc/gcc/Makefile.in
@@ -2942,7 +2942,8 @@ ipa-struct-reorg.o: ipa-struct-reorg.c
ipa-struct-reorg.h $(CONFIG_H) $(SYSTEM_H
?coverage.o : coverage.c $(GCOV_IO_H) $(CONFIG_H) $(SYSTEM_H) coretypes.h \
?? ?$(TM_H) $(RTL_H) $(TREE_H) $(FLAGS_H) output.h $(REGS_H) $(EXPR_H) \
?? ?$(FUNCTION_H) $(TOPLEV_H) $(GGC_H) langhooks.h $(COVERAGE_H) gt-coverage.h \
- ? $(HASHTAB_H) tree-iterator.h $(CGRAPH_H) $(TREE_PASS_H) gcov-io.c $(TM_P_H)
+ ? $(HASHTAB_H) tree-iterator.h $(CGRAPH_H) $(TREE_PASS_H) gcov-io.c
$(TM_P_H) \
+ ? $(DIAGNOSTIC_H)
?cselib.o : cselib.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
?? ?$(REGS_H) hard-reg-set.h $(FLAGS_H) $(REAL_H) insn-config.h $(RECOG_H) \
?? ?$(EMIT_RTL_H) $(TOPLEV_H) output.h $(FUNCTION_H) $(TREE_PASS_H) \
diff --git a/gcc/gcc/common.opt b/gcc/gcc/common.opt
index e62e3d5..806bd1f 100644
--- a/gcc/gcc/common.opt
+++ b/gcc/gcc/common.opt
@@ -249,8 +249,8 @@ Common Var(warn_unused_variable) Init(-1) Warning
?Warn when a variable is unused

?Wcoverage-mismatch
-Common RejectNegative Var(warn_coverage_mismatch) Warning
-Warn instead of error in case profiles in -fprofile-use do not match
+Common Var(warn_coverage_mismatch) Init(1) Warning
+Warn in case profiles in -fprofile-use do not match

?aux-info
?Common Separate
diff --git a/gcc/gcc/coverage.c b/gcc/gcc/coverage.c
index e04d22b..1dd89d1 100644
--- a/gcc/gcc/coverage.c
+++ b/gcc/gcc/coverage.c
@@ -46,6 +46,7 @@ along with GCC; see the file COPYING3. ?If not see
?#include "tree-iterator.h"
?#include "cgraph.h"
?#include "tree-pass.h"
+#include "diagnostic.h"

?#include "gcov-io.c"

@@ -360,31 +361,30 @@ get_coverage_counts (unsigned counter, unsigned expected,
?? ? ? tree id = DECL_ASSEMBLER_NAME (current_function_decl);

?? ? ? if (warn_coverage_mismatch)
- warning (OPT_Wcoverage_mismatch, "coverage mismatch for function "
- "%qE while reading counter %qs", id, ctr_names[counter]);
- ? ? ?else
- error ("coverage mismatch for function %qE while reading counter %qs",
- ? ? ? id, ctr_names[counter]);
-
- ? ? ?if (!inhibit_warnings)
? {
- ?if (entry->checksum != checksum)
- ? ?inform (input_location, "checksum is %x instead of %x",
entry->checksum, checksum);
- ?else
- ? ?inform (input_location, "number of counters is %d instead of %d",
- ? ?entry->summary.num, expected);
- }
+ ?warning (OPT_Wcoverage_mismatch, "coverage mismatch for function "
+ ? "%qE while reading counter %qs", id, ctr_names[counter]);

- ? ? ?if (warn_coverage_mismatch
- ?&& !inhibit_warnings
- ?&& !warned++)
- {
- ?inform (input_location, "coverage mismatch ignored due to
-Wcoverage-mismatch");
- ?inform (input_location, flag_guess_branch_prob
- ?? "execution counts estimated"
- ?: "execution counts assumed to be zero");
- ?if (!flag_guess_branch_prob)
- ? ?inform (input_location, "this can result in poorly optimized code");
+ ?if (!inhibit_warnings)
+ ? ?{
+ ? ? ?if (entry->checksum != checksum)
+ inform (input_location, "checksum is %x instead of %x",
entry->checksum, checksum);
+ ? ? ?else
+ inform (input_location, "number of counters is %d instead of %d",
+ entry->summary.num, expected);
+ ? ?}
+
+ ?if (!(errorcount || sorrycount)
+ ? ? ?&& !inhibit_warnings
+ ? ? ?&& !warned++)
+ ? ?{
+ ? ? ?inform (input_location, "coverage mismatch ignored");
+ ? ? ?inform (input_location, flag_guess_branch_prob
+ ? ? ?? "execution counts estimated"
+ ? ? ?: "execution counts assumed to be zero");
+ ? ? ?if (!flag_guess_branch_prob)
+ inform (input_location, "this can result in poorly optimized code");
+ ? ?}
? }

?? ? ? return NULL;
diff --git a/gcc/gcc/doc/invoke.texi b/gcc/gcc/doc/invoke.texi
index fefb0ab..492b82b 100644
--- a/gcc/gcc/doc/invoke.texi
+++ b/gcc/gcc/doc/invoke.texi
@@ -2746,12 +2746,13 @@ Warn if feedback profiles do not match when using the
?If a source file was changed between @option{-fprofile-gen} and
?@option{-fprofile-use}, the files with the profile feedback can fail
?to match the source file and GCC can not use the profile feedback
-information. ?By default, GCC emits an error message in this case.
-The option @option{-Wcoverage-mismatch} emits a warning instead of an
-error. ?GCC does not use appropriate feedback profiles, so using this
-option can result in poorly optimized code. ?This option is useful
-only in the case of very minor changes such as bug fixes to an
-existing code-base.
+information. ?By default, this warning is enabled and is treated as an
+error. ?@option{-Wno-coverage-mismatch} can be used to disable the
+warning or @option{-Wno-error=coverage-mismatch} can be used to
+disable the error. ?Disable the error for this warning can result in
+poorly optimized code, so disabling the error is useful only in the
+case of very minor changes such as bug fixes to an existing code-base.
+Completely disabling the warning is not recommended.

?@end table

diff --git a/gcc/gcc/opts.c b/gcc/gcc/opts.c
index 507b502..e5562ab 100644
--- a/gcc/gcc/opts.c
+++ b/gcc/gcc/opts.c
@@ -767,6 +767,11 @@ handle_options (unsigned int argc, const char
**argv, unsigned int lang_mask)
?? ? }
?}

+
+/* Callback function, called when -Werror= enables a warning. ?*/
+
+static void (*warning_as_error_callback) (int) = NULL;
+
?/* Parse command line options and set default flag values. ?Do minimal
?? ?options processing. ?*/
?void
@@ -946,6 +951,11 @@ decode_options (unsigned int argc, const char **argv)
?? else
?? ? set_param_value ("min-crossjump-insns", initial_min_crossjump_insns);

+ ?/* Enable -Werror=coverage-mismatch by default */
+ ?diagnostic_classify_diagnostic (global_dc, OPT_Wcoverage_mismatch, DK_ERROR);
+ ?if (warning_as_error_callback)
+ ? ?warning_as_error_callback (OPT_Wcoverage_mismatch);
+
?? if (first_time_p)
?? ? {
?? ? ? /* Initialize whether `char' is signed. ?*/
@@ -2406,11 +2416,6 @@ set_option (const struct cl_option *option, int
value, const char *arg)
?? ? }
?}

-
-/* Callback function, called when -Werror= enables a warning. ?*/
-
-static void (*warning_as_error_callback) (int) = NULL;
-
?/* Register a callback for enable_warning_as_error calls. ?*/

?void