[PATCH] Don't error on coverage mismatch by request

[Richard Guenther]

This makes coverage mismatch errors a warning if requested by
-Wcoverage-mismatch and assumes execution counts to be zero in
this case as we do for missing coverage info.

This allows the same profile data to be used if re-compiling with
like small bugfixes added to a big project without the need to
re-do possibly lengthy profiling.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

Ok for mainline?

Thanks,
Richard.

2006-11-23  Richard Guenther  <rguenther@suse.de>

	* doc/invoke.texi (-Wcoverage-mismatch): Document.
	* common.opt (-Wcoverage-mismatch): New warning option.
	* coverage.c (get_coverage_counts): Ignore coverage mismatch
	if -Wcoverage-mismatch is given.

Index: gcc/doc/invoke.texi
===================================================================
*** gcc/doc/invoke.texi	(revision 119120)
--- gcc/doc/invoke.texi	(working copy)
*************** Objective-C and Objective-C++ Dialects}.
*** 220,226 ****
  @gccoptlist{-fsyntax-only  -pedantic  -pedantic-errors @gol
  -w  -Wextra  -Wall  -Waggregate-return -Wno-attributes @gol
  -Wc++-compat -Wcast-align  -Wcast-qual  -Wchar-subscripts  -Wcomment @gol
! -Wconversion  -Wno-deprecated-declarations @gol
  -Wdisabled-optimization  -Wno-div-by-zero  -Wno-endif-labels @gol
  -Werror  -Werror-implicit-function-declaration @gol
  -Wfatal-errors  -Wfloat-equal  -Wformat  -Wformat=2 @gol
--- 220,226 ----
  @gccoptlist{-fsyntax-only  -pedantic  -pedantic-errors @gol
  -w  -Wextra  -Wall  -Waggregate-return -Wno-attributes @gol
  -Wc++-compat -Wcast-align  -Wcast-qual  -Wchar-subscripts  -Wcomment @gol
! -Wconversion  -Wcoverage-mismatch  -Wno-deprecated-declarations @gol
  -Wdisabled-optimization  -Wno-div-by-zero  -Wno-endif-labels @gol
  -Werror  -Werror-implicit-function-declaration @gol
  -Wfatal-errors  -Wfloat-equal  -Wformat  -Wformat=2 @gol
*************** Make all warnings into errors.
*** 3400,3405 ****
--- 3400,3417 ----
  This option is only active when @option{-fstack-protector} is active.  It
  warns about functions that will not be protected against stack smashing.
  
+ @item -Wcoverage-mismatch
+ @opindex Wcoverage-mismatch
+ Warn if feedback profiles do not match when using the
+ @option{-fprofile-use} option.
+ If a source file was changed between @option{-fprofile-gen} and
+ @option{-fprofile-use}, the files with the profile feedback do not
+ 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, but the
+ compilation runs without errors.
+ 
  @end table
  
  @node Debugging Options
*************** The following options are enabled: @code
*** 5395,5400 ****
--- 5407,5415 ----
  @code{-funroll-loops}, @code{-fpeel-loops}, @code{-ftracer},
  @code{-fno-loop-optimize}.
  
+ By default, GCC emits an error message if the feedback profiles do not
+ match. The error abort can be avoided by using
+ @option{-Wcoverage-mismatch}. 
  @end table
  
  The following options control compiler behavior regarding floating
Index: gcc/coverage.c
===================================================================
*** gcc/coverage.c	(revision 119120)
--- gcc/coverage.c	(working copy)
*************** get_coverage_counts (unsigned counter, u
*** 351,370 ****
      }
  
    checksum = compute_checksum ();
!   if (entry->checksum != checksum)
      {
!       error ("coverage mismatch for function %qs while reading counter %qs",
! 	     IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (current_function_decl)),
! 	     ctr_names[counter]);
!       error ("checksum is %x instead of %x", entry->checksum, checksum);
!       return 0;
!     }
!   else if (entry->summary.num != expected)
!     {
!       error ("coverage mismatch for function %qs while reading counter %qs",
! 	     IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (current_function_decl)),
! 	     ctr_names[counter]);
!       error ("number of counters is %d instead of %d", entry->summary.num, expected);
        return 0;
      }
  
--- 351,381 ----
      }
  
    checksum = compute_checksum ();
!   if (entry->checksum != checksum
!       || entry->summary.num != expected)
      {
!       const char *id = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME
! 			 (current_function_decl));
! 
!       if (warn_coverage_mismatch)
! 	warning (OPT_Wcoverage_mismatch, "coverage mismatch for function "
! 		 "%qs while reading counter %qs", id, ctr_names[counter]);
!       else
! 	error ("coverage mismatch for function %qs while reading counter %qs",
! 	       id, ctr_names[counter]);
! 
!       if (entry->checksum != checksum)
! 	inform ("checksum is %x instead of %x", entry->checksum, checksum);
!       else
! 	inform ("number of counters is %d instead of %d",
! 		entry->summary.num, expected);
! 
!       if (warn_coverage_mismatch)
! 	{
! 	  inform ("coverage mismatch ignored due to -Wcoverage-mismatch");
! 	  inform ("execution counts assumed to be zero");
! 	}
! 
        return 0;
      }
  
Index: gcc/common.opt
===================================================================
*** gcc/common.opt	(revision 119120)
--- gcc/common.opt	(working copy)
*************** Wvolatile-register-var
*** 177,182 ****
--- 177,186 ----
  Common Var(warn_register_var)
  Warn when a register variable is declared volatile
  
+ Wcoverage-mismatch
+ Common Var(warn_coverage_mismatch)
+ Warn when profiles in -fprofile-use do not match
+ 
  aux-info
  Common Separate
  -aux-info <file>	Emit declaration information into <file>