[patch] Add discriminators to DWARF line table
Cary Coutant
ccoutant@google.com
Wed Jun 3 01:03:00 GMT 2009
>>> + from = expand_location (locus1);
>>> + to = expand_location (locus2);
>>> + return (from.file == to.file && from.line == to.line);
>>
>> Are file name strings canonicalized by the location_t code? I
>> assume they are, but I'm not sure. If not, you may need a better
>> matching code here.
>
> I checked this experimentally, but I'll delve deeper into the code to make sure.
It looks like the string pointers may not be the same if there's an
intervening #line directive. I've changed this to do a quick pointer
comparison, then fall back to a strcmp:
if (from.line != to.line)
return false;
if (from.file == to.file)
return true;
return strcmp (from.file, to.file);
New patch is attached. I've done an overdue svn update on my working
copy, so I'll bootstrap and test again. Assuming that works, is this
OK?
-cary
* basic-block.h (struct basic_block_def): Add discriminator field.
* dbxout.c (dbxout_source_line): Add new parameter. Change all
callers.
* debug.c (do_nothing_debug_hooks): Add additional entry.
(debug_nothing_int_charstar_int): New function.
* debug.h (struct gcc_debug_hooks): Add parameter to source_line
hook.
(debug_nothing_int_charstar_int): New declaration.
* dwarf2out.c (dwarf2out_source_line): Add new parameter. Write
discriminator value in .loc directive.
* final.c (last_discriminator): New variable.
(discriminator): New variable.
(final_start_function): Initialize above variables, pass current
discriminator to debug hook.
(notice_source_line): Check for discriminator change.
* gimple-pretty-print.c (dump_bb_header): Print discriminator value.
* sdbout.c (sdbout_source_line): New parameter.
* tree-cfg.c (struct locus_discrim_map): New structure type.
(discriminator_per_locus): New hash table.
(build_gimple_cfg): Allocate and free discriminator hash table.
(make_edges): Call assign_discriminator.
(locus_map_hash): New function.
(locus_map_eq): New function.
(next_discriminator_for_locus): New function.
(same_line_p): New function.
(assign_discriminator): New function.
(make_cond_expr_edges): Call assign_discriminator.
(make_gimple_switch_edges): Likewise.
(first_non_label_stmt): New function.
* vmsdbgout.c (vmsdbgout_source_line): Add new parameter. Change
all callers.
* xcoffout.c (xcoffout_source_line): Add new parameter.
* configure.ac (gcc_cv_as_discriminator): New configury check for
gas support for discriminator.
* configure: Regenerate.
* config.in: Regenerate.
-------------- next part --------------
Index: basic-block.h
===================================================================
--- basic-block.h (revision 148110)
+++ basic-block.h (working copy)
@@ -249,6 +249,9 @@ struct GTY((chain_next ("%h.next_bb"), c
/* Expected frequency. Normalized to be in range 0 to BB_FREQ_MAX. */
int frequency;
+ /* The discriminator for this block. */
+ int discriminator;
+
/* Various flags. See BB_* below. */
int flags;
};
Index: configure.ac
===================================================================
--- configure.ac (revision 148110)
+++ configure.ac (working copy)
@@ -2408,6 +2408,15 @@ AC_DEFINE_UNQUOTED(HAVE_COMDAT_GROUP,
[`if test $gcc_cv_as_comdat_group = yes || test $gcc_cv_as_comdat_group_percent = yes; then echo 1; else echo 0; fi`],
[Define 0/1 if your assembler and linker support COMDAT groups.])
+gcc_GAS_CHECK_FEATURE([line table discriminator support],
+ gcc_cv_as_discriminator,
+ [2,19,51],,
+[ .text
+ .file 1 "conf.c"
+ .loc 1 1 0 discriminator 1],,
+[AC_DEFINE(HAVE_GAS_DISCRIMINATOR, 1,
+ [Define if your assembler supports the .loc discriminator sub-directive.])])
+
# Thread-local storage - the check is heavily parameterized.
conftest_s=
tls_first_major=
Index: dbxout.c
===================================================================
--- dbxout.c (revision 148110)
+++ dbxout.c (working copy)
@@ -333,7 +333,7 @@ static void dbxout_handle_pch (unsigned)
/* The debug hooks structure. */
#if defined (DBX_DEBUGGING_INFO)
-static void dbxout_source_line (unsigned int, const char *);
+static void dbxout_source_line (unsigned int, const char *, int);
static void dbxout_begin_prologue (unsigned int, const char *);
static void dbxout_source_file (const char *);
static void dbxout_function_end (tree);
@@ -1265,7 +1265,7 @@ dbxout_begin_prologue (unsigned int line
/* pre-increment the scope counter */
scope_labelno++;
- dbxout_source_line (lineno, filename);
+ dbxout_source_line (lineno, filename, 0);
/* Output function begin block at function scope, referenced
by dbxout_block, dbxout_source_line and dbxout_function_end. */
emit_pending_bincls_if_required ();
@@ -1276,7 +1276,8 @@ dbxout_begin_prologue (unsigned int line
number LINENO. */
static void
-dbxout_source_line (unsigned int lineno, const char *filename)
+dbxout_source_line (unsigned int lineno, const char *filename,
+ int discriminator ATTRIBUTE_UNUSED)
{
dbxout_source_file (filename);
Index: debug.c
===================================================================
--- debug.c (revision 148110)
+++ debug.c (working copy)
@@ -34,7 +34,7 @@ const struct gcc_debug_hooks do_nothing_
debug_nothing_int_int, /* begin_block */
debug_nothing_int_int, /* end_block */
debug_true_const_tree, /* ignore_block */
- debug_nothing_int_charstar, /* source_line */
+ debug_nothing_int_charstar_int, /* source_line */
debug_nothing_int_charstar, /* begin_prologue */
debug_nothing_int_charstar, /* end_prologue */
debug_nothing_int_charstar, /* end_epilogue */
@@ -104,6 +104,13 @@ debug_nothing_int_charstar (unsigned int
}
void
+debug_nothing_int_charstar_int (unsigned int line ATTRIBUTE_UNUSED,
+ const char *text ATTRIBUTE_UNUSED,
+ int discriminator ATTRIBUTE_UNUSED)
+{
+}
+
+void
debug_nothing_int (unsigned int line ATTRIBUTE_UNUSED)
{
}
Index: debug.h
===================================================================
--- debug.h (revision 148110)
+++ debug.h (working copy)
@@ -59,8 +59,9 @@ struct gcc_debug_hooks
though the BLOCK information is messed up. Defaults to true. */
bool (* ignore_block) (const_tree);
- /* Record a source file location at (FILE, LINE). */
- void (* source_line) (unsigned int line, const char *file);
+ /* Record a source file location at (FILE, LINE, DISCRIMINATOR). */
+ void (* source_line) (unsigned int line, const char *file,
+ int discriminator);
/* Called at start of prologue code. LINE is the first line in the
function. This has been given the same prototype as source_line,
@@ -141,6 +142,7 @@ extern const struct gcc_debug_hooks *deb
extern void debug_nothing_void (void);
extern void debug_nothing_charstar (const char *);
extern void debug_nothing_int_charstar (unsigned int, const char *);
+extern void debug_nothing_int_charstar_int (unsigned int, const char *, int);
extern void debug_nothing_int (unsigned int);
extern void debug_nothing_int_int (unsigned int, unsigned int);
extern void debug_nothing_tree (tree);
Index: dwarf2out.c
===================================================================
--- dwarf2out.c (revision 148110)
+++ dwarf2out.c (working copy)
@@ -91,7 +91,7 @@ along with GCC; see the file COPYING3.
#include "input.h"
#ifdef DWARF2_DEBUGGING_INFO
-static void dwarf2out_source_line (unsigned int, const char *);
+static void dwarf2out_source_line (unsigned int, const char *, int);
#endif
#ifndef DWARF2_FRAME_INFO
@@ -3608,7 +3608,7 @@ dwarf2out_begin_prologue (unsigned int l
prologue case, not the eh frame case. */
#ifdef DWARF2_DEBUGGING_INFO
if (file)
- dwarf2out_source_line (line, file);
+ dwarf2out_source_line (line, file, 0);
#endif
if (dwarf2out_do_cfi_asm ())
@@ -16207,7 +16207,8 @@ dwarf2out_begin_function (tree fun)
'line_info_table' for later output of the .debug_line section. */
static void
-dwarf2out_source_line (unsigned int line, const char *filename)
+dwarf2out_source_line (unsigned int line, const char *filename,
+ int discriminator)
{
if (debug_info_level >= DINFO_LEVEL_NORMAL
&& line != 0)
@@ -16224,7 +16225,12 @@ dwarf2out_source_line (unsigned int line
if (DWARF2_ASM_LINE_DEBUG_INFO)
{
/* Emit the .loc directive understood by GNU as. */
- fprintf (asm_out_file, "\t.loc %d %d 0\n", file_num, line);
+ fprintf (asm_out_file, "\t.loc %d %d 0", file_num, line);
+#ifdef HAVE_GAS_DISCRIMINATOR
+ if (discriminator != 0)
+ fprintf (asm_out_file, " discriminator %d", discriminator);
+#endif /* HAVE_GAS_DISCRIMINATOR */
+ fputc ('\n', asm_out_file);
/* Indicate that line number info exists. */
line_info_table_in_use++;
Index: final.c
===================================================================
--- final.c (revision 148110)
+++ final.c (working copy)
@@ -130,6 +130,12 @@ rtx current_output_insn;
/* Line number of last NOTE. */
static int last_linenum;
+/* Last discriminator written to assembly. */
+static int last_discriminator;
+
+/* Discriminator of current block. */
+static int discriminator;
+
/* Highest line number in current block. */
static int high_block_linenum;
@@ -1496,6 +1502,7 @@ final_start_function (rtx first ATTRIBUT
last_filename = locator_file (prologue_locator);
last_linenum = locator_line (prologue_locator);
+ last_discriminator = discriminator = 0;
high_block_linenum = high_function_linenum = last_linenum;
@@ -1852,6 +1859,8 @@ final_scan_insn (rtx insn, FILE *file, i
else
*seen |= SEEN_BB;
+ discriminator = NOTE_BASIC_BLOCK (insn)->discriminator;
+
break;
case NOTE_INSN_EH_REGION_BEG:
@@ -2183,7 +2192,9 @@ final_scan_insn (rtx insn, FILE *file, i
note in a row. */
if (notice_source_line (insn))
{
- (*debug_hooks->source_line) (last_linenum, last_filename);
+ (*debug_hooks->source_line) (last_linenum,
+ last_filename,
+ last_discriminator);
}
if (GET_CODE (body) == ASM_INPUT)
@@ -2709,11 +2720,13 @@ notice_source_line (rtx insn)
if (filename
&& (force_source_line
|| filename != last_filename
- || last_linenum != linenum))
+ || last_linenum != linenum
+ || last_discriminator != discriminator))
{
force_source_line = false;
last_filename = filename;
last_linenum = linenum;
+ last_discriminator = discriminator;
high_block_linenum = MAX (last_linenum, high_block_linenum);
high_function_linenum = MAX (last_linenum, high_function_linenum);
return true;
Index: gimple-pretty-print.c
===================================================================
--- gimple-pretty-print.c (revision 148110)
+++ gimple-pretty-print.c (working copy)
@@ -1558,6 +1558,12 @@ dump_bb_header (pretty_printer *buffer,
pp_decimal_int (buffer, get_lineno (gsi_stmt (gsi)));
break;
}
+
+ if (bb->discriminator)
+ {
+ pp_string (buffer, ", discriminator ");
+ pp_decimal_int (buffer, bb->discriminator);
+ }
}
newline_and_indent (buffer, indent);
Index: sdbout.c
===================================================================
--- sdbout.c (revision 148110)
+++ sdbout.c (working copy)
@@ -117,7 +117,7 @@ static void sdbout_start_source_file (un
static void sdbout_end_source_file (unsigned int);
static void sdbout_begin_block (unsigned int, unsigned int);
static void sdbout_end_block (unsigned int, unsigned int);
-static void sdbout_source_line (unsigned int, const char *);
+static void sdbout_source_line (unsigned int, const char *, int);
static void sdbout_end_epilogue (unsigned int, const char *);
static void sdbout_global_decl (tree);
#ifndef MIPS_DEBUGGING_INFO
@@ -1541,7 +1541,8 @@ sdbout_end_block (unsigned int line, uns
number LINE. */
static void
-sdbout_source_line (unsigned int line, const char *filename ATTRIBUTE_UNUSED)
+sdbout_source_line (unsigned int line, const char *filename ATTRIBUTE_UNUSED,
+ int discriminator ATTRIBUTE_UNUSED)
{
/* COFF relative line numbers must be positive. */
if ((int) line > sdb_begin_function_line)
Index: tree-cfg.c
===================================================================
--- tree-cfg.c (revision 148110)
+++ tree-cfg.c (working copy)
@@ -82,6 +82,14 @@ static struct cfg_stats_d cfg_stats;
/* Nonzero if we found a computed goto while building basic blocks. */
static bool found_computed_goto;
+/* Hash table to store last discriminator assigned for each locus. */
+struct locus_discrim_map
+{
+ location_t locus;
+ int discriminator;
+};
+static htab_t discriminator_per_locus;
+
/* Basic blocks and flowgraphs. */
static void make_blocks (gimple_seq);
static void factor_computed_gotos (void);
@@ -91,6 +99,9 @@ static void make_edges (void);
static void make_cond_expr_edges (basic_block);
static void make_gimple_switch_edges (basic_block);
static void make_goto_expr_edges (basic_block);
+static unsigned int locus_map_hash (const void *);
+static int locus_map_eq (const void *, const void *);
+static void assign_discriminator (location_t, basic_block);
static edge gimple_redirect_edge_and_branch (edge, basic_block);
static edge gimple_try_redirect_by_replacing_jump (edge, basic_block);
static unsigned int split_critical_edges (void);
@@ -100,6 +111,7 @@ static inline bool stmt_starts_bb_p (gim
static int gimple_verify_flow_info (void);
static void gimple_make_forwarder_block (edge);
static void gimple_cfg2vcg (FILE *);
+static gimple first_non_label_stmt (basic_block);
/* Flowgraph optimization and cleanup. */
static void gimple_merge_blocks (basic_block, basic_block);
@@ -193,8 +205,11 @@ build_gimple_cfg (gimple_seq seq)
group_case_labels ();
/* Create the edges of the flowgraph. */
+ discriminator_per_locus = htab_create (13, locus_map_hash, locus_map_eq,
+ free);
make_edges ();
cleanup_dead_labels ();
+ htab_delete (discriminator_per_locus);
/* Debugging dumps. */
@@ -650,7 +665,11 @@ make_edges (void)
fallthru = true;
if (fallthru)
- make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
+ {
+ make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
+ if (last)
+ assign_discriminator (gimple_location (last), bb->next_bb);
+ }
}
if (root_omp_region)
@@ -660,6 +679,89 @@ make_edges (void)
fold_cond_expr_cond ();
}
+/* Trivial hash function for a location_t. ITEM is a pointer to
+ a hash table entry that maps a location_t to a discriminator. */
+
+static unsigned int
+locus_map_hash (const void *item)
+{
+ return ((const struct locus_discrim_map *) item)->locus;
+}
+
+/* Equality function for the locus-to-discriminator map. VA and VB
+ point to the two hash table entries to compare. */
+
+static int
+locus_map_eq (const void *va, const void *vb)
+{
+ const struct locus_discrim_map *a = (const struct locus_discrim_map *) va;
+ const struct locus_discrim_map *b = (const struct locus_discrim_map *) vb;
+ return a->locus == b->locus;
+}
+
+/* Find the next available discriminator value for LOCUS. The
+ discriminator distinguishes among several basic blocks that
+ share a common locus, allowing for more accurate sample-based
+ profiling. */
+
+static int
+next_discriminator_for_locus (location_t locus)
+{
+ struct locus_discrim_map item;
+ struct locus_discrim_map **slot;
+
+ item.locus = locus;
+ item.discriminator = 0;
+ slot = (struct locus_discrim_map **)
+ htab_find_slot_with_hash (discriminator_per_locus, (void *) &item,
+ (hashval_t) locus, INSERT);
+ gcc_assert (slot);
+ if (*slot == HTAB_EMPTY_ENTRY)
+ {
+ *slot = XNEW (struct locus_discrim_map);
+ gcc_assert (*slot);
+ (*slot)->locus = locus;
+ (*slot)->discriminator = 0;
+ }
+ (*slot)->discriminator++;
+ return (*slot)->discriminator;
+}
+
+/* Return TRUE if LOCUS1 and LOCUS2 refer to the same source line. */
+
+static bool
+same_line_p (location_t locus1, location_t locus2)
+{
+ expanded_location from, to;
+
+ if (locus1 == locus2)
+ return true;
+
+ from = expand_location (locus1);
+ to = expand_location (locus2);
+
+ if (from.line != to.line)
+ return false;
+ if (from.file == to.file)
+ return true;
+ return strcmp (from.file, to.file);
+}
+
+/* Assign a unique discriminator value to block BB if it begins at the same
+ LOCUS as its predecessor block. */
+
+static void
+assign_discriminator (location_t locus, basic_block bb)
+{
+ gimple to_stmt;
+
+ if (locus == 0 || bb->discriminator != 0)
+ return;
+
+ to_stmt = first_non_label_stmt (bb);
+ if (to_stmt && same_line_p (locus, gimple_location (to_stmt)))
+ bb->discriminator = next_discriminator_for_locus (locus);
+}
/* Create the edges for a GIMPLE_COND starting at block BB. */
@@ -671,10 +773,13 @@ make_cond_expr_edges (basic_block bb)
basic_block then_bb, else_bb;
tree then_label, else_label;
edge e;
+ location_t entry_locus;
gcc_assert (entry);
gcc_assert (gimple_code (entry) == GIMPLE_COND);
+ entry_locus = gimple_location (entry);
+
/* Entry basic blocks for each component. */
then_label = gimple_cond_true_label (entry);
else_label = gimple_cond_false_label (entry);
@@ -684,12 +789,14 @@ make_cond_expr_edges (basic_block bb)
else_stmt = first_stmt (else_bb);
e = make_edge (bb, then_bb, EDGE_TRUE_VALUE);
+ assign_discriminator (entry_locus, then_bb);
e->goto_locus = gimple_location (then_stmt);
if (e->goto_locus)
e->goto_block = gimple_block (then_stmt);
e = make_edge (bb, else_bb, EDGE_FALSE_VALUE);
if (e)
{
+ assign_discriminator (entry_locus, else_bb);
e->goto_locus = gimple_location (else_stmt);
if (e->goto_locus)
e->goto_block = gimple_block (else_stmt);
@@ -799,8 +906,11 @@ static void
make_gimple_switch_edges (basic_block bb)
{
gimple entry = last_stmt (bb);
+ location_t entry_locus;
size_t i, n;
+ entry_locus = gimple_location (entry);
+
n = gimple_switch_num_labels (entry);
for (i = 0; i < n; ++i)
@@ -808,6 +918,7 @@ make_gimple_switch_edges (basic_block bb
tree lab = CASE_LABEL (gimple_switch_label (entry, i));
basic_block label_bb = label_to_block (lab);
make_edge (bb, label_bb, 0);
+ assign_discriminator (entry_locus, label_bb);
}
}
@@ -880,8 +991,10 @@ make_goto_expr_edges (basic_block bb)
if (simple_goto_p (goto_t))
{
tree dest = gimple_goto_dest (goto_t);
- edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
+ basic_block label_bb = label_to_block (dest);
+ edge e = make_edge (bb, label_bb, EDGE_FALLTHRU);
e->goto_locus = gimple_location (goto_t);
+ assign_discriminator (e->goto_locus, label_bb);
if (e->goto_locus)
e->goto_block = gimple_block (goto_t);
gsi_remove (&last, true);
@@ -2690,6 +2803,17 @@ first_stmt (basic_block bb)
return !gsi_end_p (i) ? gsi_stmt (i) : NULL;
}
+/* Return the first non-label statement in basic block BB. */
+
+static gimple
+first_non_label_stmt (basic_block bb)
+{
+ gimple_stmt_iterator i = gsi_start_bb (bb);
+ while (!gsi_end_p (i) && gimple_code (gsi_stmt (i)) == GIMPLE_LABEL)
+ gsi_next (&i);
+ return !gsi_end_p (i) ? gsi_stmt (i) : NULL;
+}
+
/* Return the last statement in basic block BB. */
gimple
Index: vmsdbgout.c
===================================================================
--- vmsdbgout.c (revision 148110)
+++ vmsdbgout.c (working copy)
@@ -173,7 +173,7 @@ static void vmsdbgout_end_source_file (u
static void vmsdbgout_begin_block (unsigned int, unsigned int);
static void vmsdbgout_end_block (unsigned int, unsigned int);
static bool vmsdbgout_ignore_block (const_tree);
-static void vmsdbgout_source_line (unsigned int, const char *);
+static void vmsdbgout_source_line (unsigned int, const char *, int);
static void vmsdbgout_begin_prologue (unsigned int, const char *);
static void vmsdbgout_end_prologue (unsigned int, const char *);
static void vmsdbgout_end_function (unsigned int);
@@ -1297,7 +1297,7 @@ vmsdbgout_end_prologue (unsigned int lin
ASM_OUTPUT_LABEL (asm_out_file, label);
/* VMS PCA expects every PC range to correlate to some line and file. */
- vmsdbgout_source_line (line, file);
+ vmsdbgout_source_line (line, file, 0);
}
}
@@ -1331,7 +1331,7 @@ vmsdbgout_end_epilogue (unsigned int lin
ASM_OUTPUT_LABEL (asm_out_file, label);
/* VMS PCA expects every PC range to correlate to some line and file. */
- vmsdbgout_source_line (line, file);
+ vmsdbgout_source_line (line, file, 0);
}
}
@@ -1533,10 +1533,11 @@ lookup_filename (const char *file_name)
'line_info_table' for later output of the .debug_line section. */
static void
-vmsdbgout_source_line (register unsigned line, register const char *filename)
+vmsdbgout_source_line (register unsigned line, register const char *filename,
+ int discriminator)
{
if (write_symbols == VMS_AND_DWARF2_DEBUG)
- (*dwarf2_debug_hooks.source_line) (line, filename);
+ (*dwarf2_debug_hooks.source_line) (line, filename, discriminator);
if (debug_info_level >= DINFO_LEVEL_TERSE)
{
Index: xcoffout.c
===================================================================
--- xcoffout.c (revision 148110)
+++ xcoffout.c (working copy)
@@ -321,7 +321,8 @@ xcoffout_source_file (FILE *file, const
/* Output a line number symbol entry for location (FILENAME, LINE). */
void
-xcoffout_source_line (unsigned int line, const char *filename)
+xcoffout_source_line (unsigned int line, const char *filename,
+ int discriminator ATTRIBUTE_UNUSED)
{
bool inline_p = (strcmp (xcoff_current_function_file, filename) != 0
|| (int) line < xcoff_begin_function_line);
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