Hi!
The following testcase results in -fcompare-debug failure.
The problem is the similar like in PR94272
https://gcc.gnu.org/pipermail/gcc-patches/2020-March/542562.html
When genericizing, with -g0 we have just a TREE_SIDE_EFFECTS DO_STMT
in a branch of if, while with -g we have that wrapped into
TREE_SIDE_EFFECTS STATEMENT_LIST containing DEBUG_BEGIN_STMT and that
DO_STMT.
The do loop is empty with 0 condition, so c_genericize_control_stmt
turns it into an empty statement (without TREE_SIDE_EFFECTS).
For -g0 that means that suddenly the if branch doesn't have side effects
and is expanded differently. But with -g we still have TREE_SIDE_EFFECTS
STATEMENT_LIST containing DEBUG_BEGIN_STMT and non-TREE_SIDE_EFFECTS stmt.
The following patch fixes that by detecting this case and removing
TREE_SIDE_EFFECTS.
And, so that we don't duplicate the same code, changes the C++ FE to
just call the c_genericize_control_stmt function that can now handle it.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-03-18 Jakub Jelinek <ja...@redhat.com>
PR debug/99230
* c-gimplify.c (c_genericize_control_stmt): Handle STATEMENT_LIST.
* cp-gimplify.c (cp_genericize_r) <case STATEMENT_LIST>: Remove
special code, instead call c_genericize_control_stmt.
* gcc.dg/pr99230.c: New test.
--- gcc/c-family/c-gimplify.c.jj 2021-01-04 10:25:50.402102825 +0100
+++ gcc/c-family/c-gimplify.c 2021-03-17 19:19:20.052702095 +0100
@@ -497,6 +497,35 @@ c_genericize_control_stmt (tree *stmt_p,
genericize_omp_for_stmt (stmt_p, walk_subtrees, data, func, lh);
break;
+ case STATEMENT_LIST:
+ if (TREE_SIDE_EFFECTS (stmt))
+ {
+ tree_stmt_iterator i;
+ int nondebug_stmts = 0;
+ bool clear_side_effects = true;
+ /* Genericization can clear TREE_SIDE_EFFECTS, e.g. when
+ transforming an IF_STMT into COND_EXPR. If such stmt
+ appears in a STATEMENT_LIST that contains only that
+ stmt and some DEBUG_BEGIN_STMTs, without -g where the
+ STATEMENT_LIST wouldn't be present at all the resulting
+ expression wouldn't have TREE_SIDE_EFFECTS set, so make sure
+ to clear it even on the STATEMENT_LIST in such cases. */
+ for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
+ {
+ tree t = tsi_stmt (i);
+ if (TREE_CODE (t) != DEBUG_BEGIN_STMT && nondebug_stmts < 2)
+ nondebug_stmts++;
+ walk_tree_1 (tsi_stmt_ptr (i), func, data, NULL, lh);
+ if (TREE_CODE (t) != DEBUG_BEGIN_STMT
+ && (nondebug_stmts > 1 || TREE_SIDE_EFFECTS (tsi_stmt (i))))
+ clear_side_effects = false;
+ }
+ if (clear_side_effects)
+ TREE_SIDE_EFFECTS (stmt) = 0;
+ *walk_subtrees = 0;
+ }
+ break;
+
default:
break;
}
--- gcc/cp/cp-gimplify.c.jj 2021-03-04 09:42:27.602123905 +0100
+++ gcc/cp/cp-gimplify.c 2021-03-17 19:38:42.743888589 +0100
@@ -1464,35 +1464,6 @@ cp_genericize_r (tree *stmt_p, int *walk
walk_subtrees = 0;
break;
- case STATEMENT_LIST:
- if (TREE_SIDE_EFFECTS (stmt))
- {
- tree_stmt_iterator i;
- int nondebug_stmts = 0;
- bool clear_side_effects = true;
- /* Genericization can clear TREE_SIDE_EFFECTS, e.g. when
- transforming an IF_STMT into COND_EXPR. If such stmt
- appears in a STATEMENT_LIST that contains only that
- stmt and some DEBUG_BEGIN_STMTs, without -g where the
- STATEMENT_LIST wouldn't be present at all the resulting
- expression wouldn't have TREE_SIDE_EFFECTS set, so make sure
- to clear it even on the STATEMENT_LIST in such cases. */
- for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
- {
- tree t = tsi_stmt (i);
- if (TREE_CODE (t) != DEBUG_BEGIN_STMT && nondebug_stmts < 2)
- nondebug_stmts++;
- cp_walk_tree (tsi_stmt_ptr (i), cp_genericize_r, data, NULL);
- if (TREE_CODE (t) != DEBUG_BEGIN_STMT
- && (nondebug_stmts > 1 || TREE_SIDE_EFFECTS (tsi_stmt (i))))
- clear_side_effects = false;
- }
- if (clear_side_effects)
- TREE_SIDE_EFFECTS (stmt) = 0;
- *walk_subtrees = 0;
- }
- break;
-
case OMP_DISTRIBUTE:
/* Need to explicitly instantiate copy ctors on class iterators of
composite distribute parallel for. */
@@ -1566,6 +1537,7 @@ cp_genericize_r (tree *stmt_p, int *walk
case OMP_SIMD:
case OMP_LOOP:
case OACC_LOOP:
+ case STATEMENT_LIST:
/* These cases are handled by shared code. */
c_genericize_control_stmt (stmt_p, walk_subtrees, data,
cp_genericize_r, cp_walk_subtrees);
--- gcc/testsuite/gcc.dg/pr99230.c.jj 2021-03-17 19:34:26.633711074 +0100
+++ gcc/testsuite/gcc.dg/pr99230.c 2021-03-17 19:33:30.210332887 +0100
@@ -0,0 +1,40 @@
+/* PR debug/99230 */
+/* { dg-do compile } */
+/* { dg-options "-O2 --param logical-op-non-short-circuit=0 -fcompare-debug
--param=jump-table-max-growth-ratio-for-speed=5000" } */
+
+extern void fn2 (void);
+extern void fn3 (int);
+int a, b;
+void
+fn1 (void)
+{
+ int c;
+ short d;
+ switch (a) {
+ case 22000:
+ fn2 ();
+ case 22300:
+ b = 0;
+ case 22600:
+ case 22601:
+ case 22900:
+ fn3 (1);
+ case 20100:
+ fn3 (2);
+ case 20200:
+ fn3 (3);
+ case 20300:
+ fn3 (4);
+ case 20400:
+ fn3 (5);
+ case 20310:
+ fn3 (4);
+ case 20410:
+ fn3 (5);
+ }
+ if (d || c) {
+ do
+ ;
+ while (0);
+ }
+}
Jakub
