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problem with -fprofile-arcs and -O3 (again)
- To: egcs-patches at cygnus dot com
- Subject: problem with -fprofile-arcs and -O3 (again)
- From: Herman ten Brugge <Haj dot Ten dot Brugge at net dot HCC dot nl>
- Date: Thu, 15 Oct 1998 21:48:30 +0100 (WEST)
Hello,
I detected a small problem when compiling programs with -fprofile-arcs and
-O3. When this is done the constructor function is sometimes not generated
for small programs.
The following code demonstrates the problem:
int main() { return 0; }
When compiled with '-fprofile-arcs -O3' the constructor function
'_GLOBAL_.I.mainGCOV' is missing. When compiled with -O2 instead of -O3
the '_GLOBAL_.I.mainGCOV' is present again. I corrected this problem in
toplev.c. The problem was that code generation is deferred when -O3 is used.
I modified the code to run two passes on the deferred functions. After the
first pass output_func_start_profiler is called which will output the
constructer. The second pass will then output the code for this function.
Herman.
--- toplev.c.org Thu Oct 15 21:13:59 1998
+++ toplev.c Thu Oct 15 21:12:24 1998
@@ -2522,7 +2522,7 @@ static void
compile_file (name)
char *name;
{
- tree globals;
+ int pass;
int start_time;
int name_specified = name != 0;
@@ -2797,8 +2797,6 @@ compile_file (name)
poplevel (0, 0, 0);
}
- output_func_start_profiler ();
-
/* Compilation is now finished except for writing
what's left of the symbol table output. */
@@ -2807,196 +2805,201 @@ compile_file (name)
parse_time -= integration_time;
parse_time -= varconst_time;
- globals = getdecls ();
/* Really define vars that have had only a tentative definition.
Really output inline functions that must actually be callable
- and have not been output so far. */
+ and have not been output so far.
+ We need two passes because we can call output_func_start_profiler
+ only after we have output at least one function. */
- {
- int len = list_length (globals);
- tree *vec = (tree *) alloca (sizeof (tree) * len);
- int i;
- tree decl;
- int reconsider = 1;
-
- /* Process the decls in reverse order--earliest first.
- Put them into VEC from back to front, then take out from front. */
-
- for (i = 0, decl = globals; i < len; i++, decl = TREE_CHAIN (decl))
- vec[len - i - 1] = decl;
-
- for (i = 0; i < len; i++)
- {
- decl = vec[i];
-
- /* We're not deferring this any longer. */
- DECL_DEFER_OUTPUT (decl) = 0;
-
- if (TREE_CODE (decl) == VAR_DECL && DECL_SIZE (decl) == 0
- && incomplete_decl_finalize_hook != 0)
- (*incomplete_decl_finalize_hook) (decl);
- }
-
- /* Now emit any global variables or functions that we have been putting
- off. We need to loop in case one of the things emitted here
- references another one which comes earlier in the list. */
- while (reconsider)
- {
- reconsider = 0;
- for (i = 0; i < len; i++)
- {
- decl = vec[i];
-
- if (TREE_ASM_WRITTEN (decl) || DECL_EXTERNAL (decl))
- continue;
-
- /* Don't write out static consts, unless we still need them.
-
- We also keep static consts if not optimizing (for debugging),
- unless the user specified -fno-keep-static-consts.
- ??? They might be better written into the debug information.
- This is possible when using DWARF.
-
- A language processor that wants static constants to be always
- written out (even if it is not used) is responsible for
- calling rest_of_decl_compilation itself. E.g. the C front-end
- calls rest_of_decl_compilation from finish_decl.
- One motivation for this is that is conventional in some
- environments to write things like:
- static const char rcsid[] = "... version string ...";
- intending to force the string to be in the executable.
-
- A language processor that would prefer to have unneeded
- static constants "optimized away" would just defer writing
- them out until here. E.g. C++ does this, because static
- constants are often defined in header files.
-
- ??? A tempting alternative (for both C and C++) would be
- to force a constant to be written if and only if it is
- defined in a main file, as opposed to an include file. */
-
- if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl)
- && (! TREE_READONLY (decl)
- || TREE_PUBLIC (decl)
- || (!optimize && flag_keep_static_consts)
- || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
- {
- reconsider = 1;
- rest_of_decl_compilation (decl, NULL_PTR, 1, 1);
- }
-
- if (TREE_CODE (decl) == FUNCTION_DECL
- && DECL_INITIAL (decl) != 0
- && DECL_SAVED_INSNS (decl) != 0
- && (flag_keep_inline_functions
- || TREE_PUBLIC (decl)
- || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
- {
- reconsider = 1;
- temporary_allocation ();
- output_inline_function (decl);
- permanent_allocation (1);
- }
- }
- }
-
- /* Now that all possible functions have been output, we can dump
- the exception table. */
-
- output_exception_table ();
-
- for (i = 0; i < len; i++)
- {
- decl = vec[i];
-
- if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl)
- && ! TREE_ASM_WRITTEN (decl))
- /* Cancel the RTL for this decl so that, if debugging info
- output for global variables is still to come,
- this one will be omitted. */
- DECL_RTL (decl) = NULL;
-
- /* Warn about any function
- declared static but not defined.
- We don't warn about variables,
- because many programs have static variables
- that exist only to get some text into the object file. */
- if (TREE_CODE (decl) == FUNCTION_DECL
- && (warn_unused
- || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
- && DECL_INITIAL (decl) == 0
- && DECL_EXTERNAL (decl)
- && ! DECL_ARTIFICIAL (decl)
- && ! TREE_PUBLIC (decl))
- {
- pedwarn_with_decl (decl,
- "`%s' declared `static' but never defined");
- /* This symbol is effectively an "extern" declaration now. */
- TREE_PUBLIC (decl) = 1;
- assemble_external (decl);
- }
-
- /* Warn about static fns or vars defined but not used,
- but not about inline functions or static consts
- since defining those in header files is normal practice. */
- if (warn_unused
- && ((TREE_CODE (decl) == FUNCTION_DECL && ! DECL_INLINE (decl))
- || (TREE_CODE (decl) == VAR_DECL && ! TREE_READONLY (decl)))
- && ! DECL_IN_SYSTEM_HEADER (decl)
- && ! DECL_EXTERNAL (decl)
- && ! TREE_PUBLIC (decl)
- && ! TREE_USED (decl)
- && (TREE_CODE (decl) == FUNCTION_DECL || ! DECL_REGISTER (decl))
- /* The TREE_USED bit for file-scope decls
- is kept in the identifier, to handle multiple
- external decls in different scopes. */
- && ! TREE_USED (DECL_NAME (decl)))
- warning_with_decl (decl, "`%s' defined but not used");
+ for (pass = 0 ; pass < 2 ; pass++)
+ {
+ tree globals = getdecls ();
+ int len = list_length (globals);
+ tree *vec = (tree *) alloca (sizeof (tree) * len);
+ int i;
+ tree decl;
+ int reconsider = 1;
+
+ /* Process the decls in reverse order--earliest first.
+ Put them into VEC from back to front, then take out from front. */
+
+ for (i = 0, decl = globals; i < len; i++, decl = TREE_CHAIN (decl))
+ vec[len - i - 1] = decl;
+
+ for (i = 0; i < len; i++)
+ {
+ decl = vec[i];
+
+ /* We're not deferring this any longer. */
+ DECL_DEFER_OUTPUT (decl) = 0;
+
+ if (TREE_CODE (decl) == VAR_DECL && DECL_SIZE (decl) == 0
+ && incomplete_decl_finalize_hook != 0)
+ (*incomplete_decl_finalize_hook) (decl);
+ }
+
+ /* Now emit any global variables or functions that we have been putting
+ off. We need to loop in case one of the things emitted here
+ references another one which comes earlier in the list. */
+ while (reconsider)
+ {
+ reconsider = 0;
+ for (i = 0; i < len; i++)
+ {
+ decl = vec[i];
+
+ if (TREE_ASM_WRITTEN (decl) || DECL_EXTERNAL (decl))
+ continue;
+
+ /* Don't write out static consts, unless we still need them.
+
+ We also keep static consts if not optimizing (for debugging),
+ unless the user specified -fno-keep-static-consts.
+ ??? They might be better written into the debug information.
+ This is possible when using DWARF.
+
+ A language processor that wants static constants to be always
+ written out (even if it is not used) is responsible for
+ calling rest_of_decl_compilation itself. E.g. the C front-end
+ calls rest_of_decl_compilation from finish_decl.
+ One motivation for this is that is conventional in some
+ environments to write things like:
+ static const char rcsid[] = "... version string ...";
+ intending to force the string to be in the executable.
+
+ A language processor that would prefer to have unneeded
+ static constants "optimized away" would just defer writing
+ them out until here. E.g. C++ does this, because static
+ constants are often defined in header files.
+
+ ??? A tempting alternative (for both C and C++) would be
+ to force a constant to be written if and only if it is
+ defined in a main file, as opposed to an include file. */
+
+ if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl)
+ && (! TREE_READONLY (decl)
+ || TREE_PUBLIC (decl)
+ || (!optimize && flag_keep_static_consts)
+ || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
+ {
+ reconsider = 1;
+ rest_of_decl_compilation (decl, NULL_PTR, 1, 1);
+ }
+
+ if (TREE_CODE (decl) == FUNCTION_DECL
+ && DECL_INITIAL (decl) != 0
+ && DECL_SAVED_INSNS (decl) != 0
+ && (flag_keep_inline_functions
+ || TREE_PUBLIC (decl)
+ || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
+ {
+ reconsider = 1;
+ temporary_allocation ();
+ output_inline_function (decl);
+ permanent_allocation (1);
+ }
+ }
+ }
+
+ /* Now that all possible functions have been output, we can dump
+ the exception table. */
+
+ output_exception_table ();
+
+ for (i = 0; i < len; i++)
+ {
+ decl = vec[i];
+
+ if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl)
+ && ! TREE_ASM_WRITTEN (decl))
+ /* Cancel the RTL for this decl so that, if debugging info
+ output for global variables is still to come,
+ this one will be omitted. */
+ DECL_RTL (decl) = NULL;
+
+ /* Warn about any function
+ declared static but not defined.
+ We don't warn about variables,
+ because many programs have static variables
+ that exist only to get some text into the object file. */
+ if (TREE_CODE (decl) == FUNCTION_DECL
+ && (warn_unused
+ || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
+ && DECL_INITIAL (decl) == 0
+ && DECL_EXTERNAL (decl)
+ && ! DECL_ARTIFICIAL (decl)
+ && ! TREE_PUBLIC (decl))
+ {
+ pedwarn_with_decl (decl,
+ "`%s' declared `static' but never defined");
+ /* This symbol is effectively an "extern" declaration now. */
+ TREE_PUBLIC (decl) = 1;
+ assemble_external (decl);
+ }
+
+ /* Warn about static fns or vars defined but not used,
+ but not about inline functions or static consts
+ since defining those in header files is normal practice. */
+ if (warn_unused
+ && ((TREE_CODE (decl) == FUNCTION_DECL && ! DECL_INLINE (decl))
+ || (TREE_CODE (decl) == VAR_DECL && ! TREE_READONLY (decl)))
+ && ! DECL_IN_SYSTEM_HEADER (decl)
+ && ! DECL_EXTERNAL (decl)
+ && ! TREE_PUBLIC (decl)
+ && ! TREE_USED (decl)
+ && (TREE_CODE (decl) == FUNCTION_DECL || ! DECL_REGISTER (decl))
+ /* The TREE_USED bit for file-scope decls
+ is kept in the identifier, to handle multiple
+ external decls in different scopes. */
+ && ! TREE_USED (DECL_NAME (decl)))
+ warning_with_decl (decl, "`%s' defined but not used");
#ifdef SDB_DEBUGGING_INFO
- /* The COFF linker can move initialized global vars to the end.
- And that can screw up the symbol ordering.
- By putting the symbols in that order to begin with,
- we avoid a problem. mcsun!unido!fauern!tumuc!pes@uunet.uu.net. */
- if (write_symbols == SDB_DEBUG && TREE_CODE (decl) == VAR_DECL
- && TREE_PUBLIC (decl) && DECL_INITIAL (decl)
- && ! DECL_EXTERNAL (decl)
- && DECL_RTL (decl) != 0)
- TIMEVAR (symout_time, sdbout_symbol (decl, 0));
-
- /* Output COFF information for non-global
- file-scope initialized variables. */
- if (write_symbols == SDB_DEBUG
- && TREE_CODE (decl) == VAR_DECL
- && DECL_INITIAL (decl)
- && ! DECL_EXTERNAL (decl)
- && DECL_RTL (decl) != 0
- && GET_CODE (DECL_RTL (decl)) == MEM)
- TIMEVAR (symout_time, sdbout_toplevel_data (decl));
+ /* The COFF linker can move initialized global vars to the end.
+ And that can screw up the symbol ordering.
+ By putting the symbols in that order to begin with,
+ we avoid a problem. mcsun!unido!fauern!tumuc!pes@uunet.uu.net. */
+ if (write_symbols == SDB_DEBUG && TREE_CODE (decl) == VAR_DECL
+ && TREE_PUBLIC (decl) && DECL_INITIAL (decl)
+ && ! DECL_EXTERNAL (decl)
+ && DECL_RTL (decl) != 0)
+ TIMEVAR (symout_time, sdbout_symbol (decl, 0));
+
+ /* Output COFF information for non-global
+ file-scope initialized variables. */
+ if (write_symbols == SDB_DEBUG
+ && TREE_CODE (decl) == VAR_DECL
+ && DECL_INITIAL (decl)
+ && ! DECL_EXTERNAL (decl)
+ && DECL_RTL (decl) != 0
+ && GET_CODE (DECL_RTL (decl)) == MEM)
+ TIMEVAR (symout_time, sdbout_toplevel_data (decl));
#endif /* SDB_DEBUGGING_INFO */
#ifdef DWARF_DEBUGGING_INFO
- /* Output DWARF information for file-scope tentative data object
- declarations, file-scope (extern) function declarations (which
- had no corresponding body) and file-scope tagged type declarations
- and definitions which have not yet been forced out. */
-
- if (write_symbols == DWARF_DEBUG
- && (TREE_CODE (decl) != FUNCTION_DECL || !DECL_INITIAL (decl)))
- TIMEVAR (symout_time, dwarfout_file_scope_decl (decl, 1));
+ /* Output DWARF information for file-scope tentative data object
+ declarations, file-scope (extern) function declarations (which
+ had no corresponding body) and file-scope tagged type declarations
+ and definitions which have not yet been forced out. */
+
+ if (write_symbols == DWARF_DEBUG
+ && (TREE_CODE (decl) != FUNCTION_DECL || !DECL_INITIAL (decl)))
+ TIMEVAR (symout_time, dwarfout_file_scope_decl (decl, 1));
#endif
#ifdef DWARF2_DEBUGGING_INFO
- /* Output DWARF2 information for file-scope tentative data object
- declarations, file-scope (extern) function declarations (which
- had no corresponding body) and file-scope tagged type declarations
- and definitions which have not yet been forced out. */
-
- if (write_symbols == DWARF2_DEBUG
- && (TREE_CODE (decl) != FUNCTION_DECL || !DECL_INITIAL (decl)))
- TIMEVAR (symout_time, dwarf2out_decl (decl));
-#endif
- }
- }
+ /* Output DWARF2 information for file-scope tentative data object
+ declarations, file-scope (extern) function declarations (which
+ had no corresponding body) and file-scope tagged type declarations
+ and definitions which have not yet been forced out. */
+
+ if (write_symbols == DWARF2_DEBUG
+ && (TREE_CODE (decl) != FUNCTION_DECL || !DECL_INITIAL (decl)))
+ TIMEVAR (symout_time, dwarf2out_decl (decl));
+#endif
+ }
+ if (pass == 0)
+ output_func_start_profiler();
+ }
/* Write out any pending weak symbol declarations. */
--
-------------------------------------------------------------------------
Herman ten Brugge Email: Haj.Ten.Brugge@net.HCC.nl