On 2023/3/9 20:02, Richard Biener wrote:
On Wed, 8 Mar 2023, Xionghu Luo wrote:
On 2023/3/7 19:25, Richard Biener wrote:
It would be nice to avoid creating blocks / preserving labels we'll
immediately remove again. For that we do need some analysis
before creating basic-blocks that determines whether a label is
possibly reached by a non-falltru edge.
<bb 2> :
p = 0;
switch (s) <default: <D.2756>, case 0: <L0>, case 1: <D.2744>>
<bb 3> :
<L0>: <= prev_stmt
<D.2748>: <= stmt
p = p + 1;
n = n + -1;
if (n != 0) goto <D.2748>; else goto <D.2746>;
Check if <L0> is a case label and <D.2748> is a goto target then return
true
in stmt_starts_bb_p to start a new basic block? This would avoid creating
and
removing blocks, but cleanup_dead_labels has all bbs setup while
stmt_starts_bb_p
does't yet to iterate bbs/labels to establish label_for_bb[] map?
Yes. I think we'd need something more pragmatic before make_blocks (),
like re-computing TREE_USED of the label decls or computing a bitmap
of targeted labels (targeted by goto, switch or any other means).
I'll note that doing a cleanup_dead_labels () like optimization before
we create blocks will help keeping LABEL_DECL_UID and thus
label_to_block_map dense. But it does look like a bit of
an chicken-and-egg problem and the question is how effective the
dead label removal is in practice.
Tried to add function compute_target_labels(not sure whether the function
name is suitable) in the front of make_blocks_1, now the fortran case doesn't
create/removing blocks now, but I still have several questions:
1. I used hash_set<tree> to save the target labels instead of bitmap, as
labels
are tree type value instead of block index so bitmap is not good for it since
we don't have LABEL_DECL_UID now?
We don't have LABEL_DECL_UID, we have DECL_UID though, but the choice of
hash_set<tree> vs. bitmap is somewhat arbitrary here. The real cost is
the extra walk over all stmts.
2. Is the compute_target_labels still only for !optimize? And if we compute
the target labels before create bbs, it is unnessary to guard the first
cleanup_dead_labels under !optimize now, because the switch-case-do-while
case already create new block for CASE_LABEL already.
OK.
3. I only added GIMPLE_SWITCH/GIMPLE_COND in compute_target_labels
so far, is it needed to also handle GIMPLE_ASM/GIMPLE_TRANSACTION and even
labels_eh?
I'd add GIMPLE_ASM handling, the rest should be OK wrt debugging and
coverage already?
Added in patch v4.
PS1: The v3 patch will cause one test case fail:
Number of regressions in total: 1
FAIL: gcc.c-torture/compile/limits-caselabels.c -O0 (test for excess
errors)
due to this exausting case has labels from L0 to L100001, they won't be
optimized
to a simple if-else expression like before...
Hmm, that's somewhat unexpected.
It could be fixed by not start a new block if two locus are on same line as the
labels are expanded by MACRO with same location info. BTW, I found that two
UNKOWN_LOCATION variable may have different value but return true in
same_line_p?
2: locus1 = 2147483670
3: locus2 = 2147483652
(gdb) pel locus1
{file = 0x0, line = 0, column = 0, data = 0x7ffff6bdc300, sysp = false}
(gdb) pel locus2
{file = 0x0, line = 0, column = 0, data = 0x7ffff6bdc4e0, sysp = false}
(gdb) p LOCATION_LOCUS (locus1)
$16 = 0
(gdb) p LOCATION_LOCUS (locus2)
$17 = 0
So fix the function like this?
@@ -1152,6 +1218,10 @@ same_line_p (location_t locus1, expanded_location *from,
location_t locus2)
{
expanded_location to;
+ if (LOCATION_LOCUS (locus1) == UNKNOWN_LOCATION
+ && LOCATION_LOCUS (locus2) == UNKNOWN_LOCATION)
+ return false;
+
if (locus1 == locus2)
return true;
PS2: The GIMPLE_GOTO piece of code would cause some fortran cases run fail due
to __builtin_unreachable trap generated in .fixup_cfg1, I didn't dig into it
so
just skip these label...
Please investigate, we might be missing a corner case here.
Yes. Take the case pointer_array_1.f90 as example, it has an UNUSED label "L.7"
with locus info in it, not sure why it exists even since .original.
[pointer_array_1.f90:39:10] if (test.14 != 0) goto <D.4599>; els
e goto <D.4600>;
<D.4599>:
[pointer_array_1.f90:39:52] _gfortran_stop_numeric (3, 0);
<D.4600>:
parm.16 = {CLOBBER(eol)};
[pointer_array_1.f90:39:52] L.7: <= UNUSED label
<D.4594>:
[pointer_array_1.f90:39:52] L.3:
atmp.0 = {CLOBBER(eol)};
A.1 = {CLOBBER(eol)};
atmp.5 = {CLOBBER(eol)};
A.6 = {CLOBBER(eol)};
d = {CLOBBER(eol)};
[pointer_array_1.f90:41:14] return;
stmt_starts_bb_p will return true for L.7 as the prev_stmt "parm.16 =
{CLOBBER(eol)};"
is not a label statement, then <D.4594> will also return true in
stmt_starts_bb_p as
the label_stmt and prev_stmt are NOT on same line.
<bb 38> :
L.9:
L.8:
if (test.14 != 0) goto <L39>; else goto <L40>;
<bb 39> :
<L39>:
_gfortran_stop_numeric (3, 0);
<bb 40> :
<L40>:
parm.16 = {CLOBBER(eol)};
<bb 41> : <= empty block
L.7:
<bb 42> :
<L42>:
L.3:
atmp.0 = {CLOBBER(eol)};
A.1 = {CLOBBER(eol)};
atmp.5 = {CLOBBER(eol)};
A.6 = {CLOBBER(eol)};
d = {CLOBBER(eol)};
return;
So I have to fix it with this: Return false to not start a new block when
prev_stmt
is not a label_statement and target_labels not containing the current label:
static inline bool stmt_starts_bb_p(gimple *stmt, gimple *prev_stmt,
hash_set<tree> *target_labels)
{
...
if (glabel *plabel = safe_dyn_cast <glabel *> (prev_stmt))
{
...
cfg_stats.num_merged_labels++;
return false;
}
+ else if (!optimize
+ && !target_labels->contains (gimple_label_label (label_stmt)))
<= Fix gfortran.dg failure
+ && stmt->next && gimple_code (stmt->next) == GIMPLE_LABEL)
<= Fix bootstrap failure of openacc.f90
+ return false;
else
return true;
...
}
Though this fix would caused stage3 bootstrap failure quite like the fortran
falure::
/data/src/gcc/libgomp/openacc.f90:1058:36:
1058 | subroutine acc_get_property_string_h (devicenum, devicetype, property,
string)
| ^
Error: label ‘L.3’ in the middle of basic block 13
<bb 12> :
D.4377 = i > D.4374;
if (D.4377 != 0)
goto <bb 14>; [INV]
else
goto <bb 13>; [INV]
<bb 13> :
_10 = sptr.data;
_11 = sptr.offset;
_12 = i + _11;
_13 = sptr.span;
_14 = _12 * _13;
_15 = (sizetype) _14;
_16 = _10 + _15;
_17 = MEM[(character(kind=1) *)_16];
(*string)[i]{lb: 1 sz: 1} = _17;
L.3: <= UNUSED label.
i = i + 1;
goto <bb 12>; [INV]
<bb 14> :
sptr = {CLOBBER(eol)};
<bb 15> :
<L18>:
return;
<bb 1> :
+ case GIMPLE_GOTO:
+#if 0
+ if (!computed_goto_p (stmt))
+ {
+ tree dest = gimple_goto_dest (stmt);
+ target_labels->add (dest);
+ }
+#endif
+ break;
Change the #if 0 to #if 1 result in:
Number of regressions in total: 8
FAIL: gcc.c-torture/compile/limits-caselabels.c -O0 (test for excess
FAIL: errors)
FAIL: gcc.dg/analyzer/explode-2a.c (test for excess errors)
FAIL: gcc.dg/analyzer/pragma-2.c (test for excess errors)
FAIL: gfortran.dg/bound_2.f90 -O0 execution test
FAIL: gfortran.dg/bound_7.f90 -O0 execution test
FAIL: gfortran.dg/char_result_14.f90 -O0 execution test
FAIL: gfortran.dg/pointer_array_1.f90 -O0 execution test
FAIL: gfortran.dg/select_type_15.f03 -O0 execution test
Paste the updated patch v3:
The gcov testcase adjustments look good, does the analyzer testcase
(missing in the changelog) get different CFG input?
Yes, it was different. But the analyzer case recovered with the same_line_p
check.
One thing to note is that gimple_set_bb would refresh Label uid in it,
so target_labels need also update after it to follow that change?
@@ -566,6 +632,9 @@ make_blocks_1 (gimple_seq seq, basic_block bb)
codes. */
gimple_set_bb (stmt, bb);
+ if (!optimize && gimple_code (stmt) == GIMPLE_LABEL)
+ target_labels.add (gimple_label_label (as_a<glabel *> (stmt)));
Another thing is the v4 patch will caused strange failures on libgomp.fortran
testsuites.
It only happens when running "make check" but doesn't fail on single run, and
more strangely,
the RUNTESTFLAGS doesn't work when running, it runs all cases under
libgomp.fortran instead
of vla1.f90, which makes it difficult to analyze the failures...
make check-fortran RUNTESTFLAGS="fortran.exp=vla1.f90 -v -v" -j8
single run success:
/data/./gcc/xgcc -B/data/./gcc/ -B/data/install/x86_64-linux-gnu/bin/
-B/data/install/x86_64-linux-gnu/lib/ -isystem
/data/install/x86_64-linux-gnu/include -isystem
/data/install/x86_64-linux-gnu/sys-include
/data/RocksDB_Docker/tgcc-master/libgomp/testsuite/libgomp.fortran/vla1.f90
-B/data/RocksDB_Docker/debug_master/x86_64-linux-gnu/./libgomp/
-B/data/x86_64-linux-gnu/./libgomp/.libs -I/data/x86_64-linux-gnu/./libgomp
-I/data/RocksDB_Docker/tgcc-master/libgomp/testsuite/../../include
-I/data/RocksDB_Docker/tgcc-master/libgomp/testsuite/.. -fmessage-length=0
-fno-diagnostics-show-caret -fdiagnostics-color=never -fopenmp
-B/data/x86_64-linux-gnu/./libgomp/../libquadmath/.libs/ -O0
-B/data/x86_64-linux-gnu/./libgomp/../libgfortran/.libs
-fintrinsic-modules-path=/data/x86_64-linux-gnu/./libgomp
-L/data/x86_64-linux-gnu/./libgomp/.libs
-L/data/x86_64-linux-gnu/./libgomp/../libquadmath/.libs/
-L/data/x86_64-linux-gnu/./libgomp/../libgfortran/.libs -lgfortran
-foffload=-lgfortran -lquadmath -lm -o ./vla1.exe
FAIL: libgomp.fortran/appendix-a/a.4.1.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/collapse2.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/task2.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/udr13.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/udr3.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/udr4.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla1.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla2.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla3.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla4.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla5.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla6.f90 -O0 (test for excess errors)
FAIL: libgomp.fortran/vla8.f90 -O0 (test for excess errors)
FAIL: libgomp.oacc-fortran/collapse-2.f90 -DACC_DEVICE_TYPE_host=1
-DACC_MEM_SHARED=1 -foffload=disable -O0 (test for excess errors)
FAIL: libgomp.oacc-fortran/nested-function-1.f90 -DACC_DEVICE_TYPE_host=1
-DACC_MEM_SHARED=1 -foffload=disable -O0 (test for excess errors)
UNRESOLVED: libgomp.fortran/appendix-a/a.4.1.f90 -O0 compilation failed to
produce executable
UNRESOLVED: libgomp.fortran/collapse2.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/task2.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/udr13.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/udr3.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/udr4.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla1.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla2.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla3.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla4.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla5.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla6.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.fortran/vla8.f90 -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.oacc-fortran/collapse-2.f90 -DACC_DEVICE_TYPE_host=1
-DACC_MEM_SHARED=1 -foffload=disable -O0 compilation failed to produce
executable
UNRESOLVED: libgomp.oacc-fortran/nested-function-1.f90 -DACC_DEVICE_TYPE_host=1
-DACC_MEM_SHARED=1 -foffload=disable -O0 compilation failed to
produce executable
v4: Address comments.
4.1. Handle GIMPLE_GOTO and GIMPLE_ASM.
4.2. Fix failure of limit-caselabels.c (labels on same line),
pointer_array_1.f90 (unused labels) etc.
v3: Add compute_target_labels and call it in the front of make_blocks_1.
v2: Check whether two locus are on same line.
Start a new basic block if two labels have different location when
test-coverage.
Regression tested pass on x86_64-linux-gnu and aarch64-linux-gnu, OK for
master?
gcc/ChangeLog:
PR gcov/93680
* tree-cfg.cc (stmt_starts_bb_p): Check whether the label is in
target_labels.
(compute_target_labels): New function.
(make_blocks_1): Call compute_target_labels.
(same_line_p): Return false if two locus are both
UNKOWN_LOCATION.
gcc/testsuite/ChangeLog:
PR gcov/93680
* g++.dg/gcov/gcov-1.C: Correct counts.
* gcc.misc-tests/gcov-4.c: Likewise.
* gcc.misc-tests/gcov-pr85332.c: Likewise.
* lib/gcov.exp: Also clean gcda if fail.
* gcc.misc-tests/gcov-pr93680.c: New test.
Signed-off-by: Xionghu Luo <xionghu...@tencent.com>
---
gcc/tree-cfg.cc | 91 ++++++++++++++++++++-
gcc/testsuite/g++.dg/gcov/gcov-1.C | 2 +-
gcc/testsuite/gcc.misc-tests/gcov-4.c | 2 +-
gcc/testsuite/gcc.misc-tests/gcov-pr85332.c | 2 +-
gcc/testsuite/gcc.misc-tests/gcov-pr93680.c | 24 ++++++
gcc/testsuite/lib/gcov.exp | 4 +-
6 files changed, 116 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-pr93680.c
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index a9fcc7fd050..d7ce121713e 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -164,7 +164,7 @@ static edge gimple_redirect_edge_and_branch (edge,
basic_block);
static edge gimple_try_redirect_by_replacing_jump (edge, basic_block);
/* Various helpers. */
-static inline bool stmt_starts_bb_p (gimple *, gimple *);
+static inline bool stmt_starts_bb_p (gimple *, gimple *, hash_set<tree> *);
static int gimple_verify_flow_info (void);
static void gimple_make_forwarder_block (edge);
static gimple *first_non_label_stmt (basic_block);
@@ -521,6 +521,68 @@ gimple_call_initialize_ctrl_altering (gimple *stmt)
gimple_call_set_ctrl_altering (stmt, false);
}
+/* Compute target labels to save useful labels. */
+static void
+compute_target_labels (gimple_seq seq, hash_set<tree> *target_labels)
+{
+ gimple *stmt = NULL;
+ gimple_stmt_iterator j = gsi_start (seq);
+
+ while (!gsi_end_p (j))
+ {
+ stmt = gsi_stmt (j);
+
+ switch (gimple_code (stmt))
+ {
+ case GIMPLE_COND:
+ {
+ gcond *cstmt = as_a <gcond *> (stmt);
+ tree true_label = gimple_cond_true_label (cstmt);
+ tree false_label = gimple_cond_false_label (cstmt);
+ target_labels->add (true_label);
+ target_labels->add (false_label);
+ }
+ break;
+ case GIMPLE_SWITCH:
+ {
+ gswitch *gstmt = as_a <gswitch *> (stmt);
+ size_t i, n = gimple_switch_num_labels (gstmt);
+ tree elt, label;
+ for (i = 0; i < n; i++)
+ {
+ elt = gimple_switch_label (gstmt, i);
+ label = CASE_LABEL (elt);
+ target_labels->add (label);
+ }
+ }
+ break;
+ case GIMPLE_GOTO:
+ if (!computed_goto_p (stmt))
+ {
+ tree dest = gimple_goto_dest (stmt);
+ target_labels->add (dest);
+ }
+ break;
+ case GIMPLE_ASM:
+ {
+ gasm *asm_stmt = as_a <gasm *> (stmt);
+ int i, n = gimple_asm_nlabels (asm_stmt);
+ for (i = 0; i < n; ++i)
+ {
+ tree cons = gimple_asm_label_op (asm_stmt, i);
+ target_labels->add (cons);
+ }
+ }
+ break;
+
+ default:
+ break;
+ }
+
+ gsi_next (&j);
+ }
+}
+
/* Insert SEQ after BB and build a flowgraph. */
@@ -532,6 +594,10 @@ make_blocks_1 (gimple_seq seq, basic_block bb)
gimple *prev_stmt = NULL;
bool start_new_block = true;
bool first_stmt_of_seq = true;
+ hash_set<tree> target_labels;
+
+ if (!optimize)
+ compute_target_labels (seq, &target_labels);
while (!gsi_end_p (i))
{
@@ -553,7 +619,7 @@ make_blocks_1 (gimple_seq seq, basic_block bb)
/* If the statement starts a new basic block or if we have determined
in a previous pass that we need to create a new block for STMT, do
so now. */
- if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
+ if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt,
&target_labels))
{
if (!first_stmt_of_seq)
gsi_split_seq_before (&i, &seq);
@@ -566,6 +632,9 @@ make_blocks_1 (gimple_seq seq, basic_block bb)
codes. */
gimple_set_bb (stmt, bb);
+ if (!optimize && gimple_code (stmt) == GIMPLE_LABEL)
+ target_labels.add (gimple_label_label (as_a<glabel *> (stmt)));
+
/* If STMT is a basic block terminator, set START_NEW_BLOCK for the
next iteration. */
if (stmt_ends_bb_p (stmt))
@@ -2832,7 +2901,8 @@ simple_goto_p (gimple *t)
label. */
static inline bool
-stmt_starts_bb_p (gimple *stmt, gimple *prev_stmt)
+stmt_starts_bb_p (gimple *stmt, gimple *prev_stmt,
+ hash_set<tree> *target_labels)
{
if (stmt == NULL)
return false;
@@ -2860,9 +2930,24 @@ stmt_starts_bb_p (gimple *stmt, gimple *prev_stmt)
|| !DECL_ARTIFICIAL (gimple_label_label (plabel)))
return true;
+ location_t prev_locus = gimple_location (plabel);
+ location_t locus = gimple_location (label_stmt);
+ expanded_location locus_e = expand_location (locus);
+
+ if (!optimize
+ && target_labels->contains (gimple_label_label (label_stmt))
+ && (LOCATION_LOCUS (locus) != UNKNOWN_LOCATION
+ || LOCATION_LOCUS (prev_locus) != UNKNOWN_LOCATION)
+ && !same_line_p (locus, &locus_e, prev_locus))
+ return true;
+
cfg_stats.num_merged_labels++;
return false;
}
+ else if (!optimize
+ && !target_labels->contains (gimple_label_label (label_stmt))
+ && stmt->next && gimple_code (stmt->next) == GIMPLE_LABEL)
+ return false;
else
return true;
}
diff --git a/gcc/testsuite/g++.dg/gcov/gcov-1.C
b/gcc/testsuite/g++.dg/gcov/gcov-1.C
index ee383b480a8..01e7084fb03 100644
--- a/gcc/testsuite/g++.dg/gcov/gcov-1.C
+++ b/gcc/testsuite/g++.dg/gcov/gcov-1.C
@@ -263,7 +263,7 @@ test_switch (int i, int j)
case 2:
result = do_something (1024);
break;
- case 3: /* count(3) */
+ case 3: /* count(2) */
case 4:
/* branch(67) */
if (j == 2) /* count(3) */
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-4.c
b/gcc/testsuite/gcc.misc-tests/gcov-4.c
index da7929ef7fc..792cda8cfce 100644
--- a/gcc/testsuite/gcc.misc-tests/gcov-4.c
+++ b/gcc/testsuite/gcc.misc-tests/gcov-4.c
@@ -122,7 +122,7 @@ top:
}
else
{
-else_: /* count(1) */
+else_: /* count(2) */
j = do_something (j); /* count(2) */
if (j) /* count(2) */
{
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-pr85332.c
b/gcc/testsuite/gcc.misc-tests/gcov-pr85332.c
index 73e50b19fc7..b37e760910c 100644
--- a/gcc/testsuite/gcc.misc-tests/gcov-pr85332.c
+++ b/gcc/testsuite/gcc.misc-tests/gcov-pr85332.c
@@ -7,7 +7,7 @@ int doit(int sel, int n, void *p)
switch (sel)
{
- case 0: /* count(3) */
+ case 0: /* count(1) */
do {*p0 += *p0;} while (--n); /* count(3) */
return *p0 == 0; /* count(1) */
diff --git a/gcc/testsuite/gcc.misc-tests/gcov-pr93680.c b/gcc/testsuite/gcc.misc-tests/gcov-pr93680.c
new file mode 100644
index 00000000000..2fe340c4011
--- /dev/null
+++ b/gcc/testsuite/gcc.misc-tests/gcov-pr93680.c
@@ -0,0 +1,24 @@
+/* { dg-options "-fprofile-arcs -ftest-coverage" } */
+/* { dg-do run { target native } } */
+
+int f(int s, int n)
+{
+ int p = 0;
+
+ switch (s)
+ {
+ case 0: /* count(1) */
+ do { p++; } while (--n); /* count(5) */
+ return p; /* count(1) */
+
+ case 1: /* count(1) */
+ do { p++; } while (--n); /* count(5) */
+ return p; /* count(1) */
+ }
+
+ return 0;
+}
+
+int main() { f(0, 5); f(1, 5); return 0; }
+
+/* { dg-final { run-gcov gcov-pr93680.c } } */
diff --git a/gcc/testsuite/lib/gcov.exp b/gcc/testsuite/lib/gcov.exp
index 80e74aeb220..07e1978d25d 100644
--- a/gcc/testsuite/lib/gcov.exp
+++ b/gcc/testsuite/lib/gcov.exp
@@ -424,9 +424,7 @@ proc run-gcov { args } {
}
if { $tfailed > 0 } {
fail "$testname gcov: $lfailed failures in line counts, $bfailed in branch
percentages, $cfailed in return percentages, $ifailed in intermediate format"
- if { $xfailed } {
- clean-gcov $testcase
- }
+ clean-gcov $testcase
} else {
pass "$testname gcov"
clean-gcov $testcase
--
2.27.0
