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middle-end/93519 - avoid folding stmts in obviously unreachable code

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The inliner folds stmts delayed, the following arranges things so
to not fold stmts that are obviously not reachable to avoid warnings
from those code regions.

2020-02-07  Richard Biener  <rguenther@suse.de>

	PR middle-end/93519
	* tree-inline.c (fold_marked_statements): Do a PRE walk,
	skipping unreachable regions.
	(optimize_inline_calls): Skip folding stmts when we didn't
	inline.

	* gcc.dg/Wrestrict-21.c: New testcase.
This commit is contained in:
Richard Biener 2020-02-07 12:56:18 +01:00
parent 5713834e4b
commit 3c7a03bc36
4 changed files with 142 additions and 77 deletions
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8
gcc/ChangeLog
View File

@ -1,3 +1,11 @@
2020-02-07 Richard Biener <rguenther@suse.de>
PR middle-end/93519
* tree-inline.c (fold_marked_statements): Do a PRE walk,
skipping unreachable regions.
(optimize_inline_calls): Skip folding stmts when we didn't
inline.
2020-02-07 H.J. Lu <hongjiu.lu@intel.com>
PR target/85667

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2020-02-07 Richard Biener <rguenther@suse.de>
PR middle-end/93519
* gcc.dg/Wrestrict-21.c: New testcase.
2020-02-07 H.J. Lu <hongjiu.lu@intel.com>
PR target/85667

18
gcc/testsuite/gcc.dg/Wrestrict-21.c Normal file
View File

@ -0,0 +1,18 @@
/* { dg-do compile } */
/* { dg-options "-O2 -Wrestrict" } */
static char *
str_numth(char *dest, char *num, int type)
{
if (dest != num)
__builtin_strcpy(dest, num); /* { dg-bogus "is the same" } */
__builtin_strcat(dest, "foo");
return dest;
}
void
DCH_to_char(char *in, char *out, int collid)
{
char *s = out;
str_numth(s, s, 42);
}

188
gcc/tree-inline.c
View File

@ -5261,86 +5261,117 @@ static void
fold_marked_statements (int first, hash_set<gimple *> *statements)
{
auto_bitmap to_purge;
for (; first < last_basic_block_for_fn (cfun); first++)
if (BASIC_BLOCK_FOR_FN (cfun, first))
{
gimple_stmt_iterator gsi;
for (gsi = gsi_start_bb (BASIC_BLOCK_FOR_FN (cfun, first));
!gsi_end_p (gsi);
gsi_next (&gsi))
if (statements->contains (gsi_stmt (gsi)))
{
gimple *old_stmt = gsi_stmt (gsi);
tree old_decl
= is_gimple_call (old_stmt) ? gimple_call_fndecl (old_stmt) : 0;
auto_vec<edge, 20> stack (n_basic_blocks_for_fn (cfun) + 2);
auto_sbitmap visited (last_basic_block_for_fn (cfun));
bitmap_clear (visited);
if (old_decl && fndecl_built_in_p (old_decl))
{
/* Folding builtins can create multiple instructions,
we need to look at all of them. */
gimple_stmt_iterator i2 = gsi;
gsi_prev (&i2);
if (fold_stmt (&gsi))
{
gimple *new_stmt;
/* If a builtin at the end of a bb folded into nothing,
the following loop won't work. */
if (gsi_end_p (gsi))
{
cgraph_update_edges_for_call_stmt (old_stmt,
old_decl, NULL);
break;
}
if (gsi_end_p (i2))
i2 = gsi_start_bb (BASIC_BLOCK_FOR_FN (cfun, first));
else
stack.quick_push (single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
while (!stack.is_empty ())
{
/* Look at the edge on the top of the stack. */
edge e = stack.pop ();
basic_block dest = e->dest;
if (dest == EXIT_BLOCK_PTR_FOR_FN (cfun)
|| bitmap_bit_p (visited, dest->index))
continue;
bitmap_set_bit (visited, dest->index);
if (dest->index >= first)
for (gimple_stmt_iterator gsi = gsi_start_bb (dest);
!gsi_end_p (gsi); gsi_next (&gsi))
{
if (!statements->contains (gsi_stmt (gsi)))
continue;
gimple *old_stmt = gsi_stmt (gsi);
tree old_decl = (is_gimple_call (old_stmt)
? gimple_call_fndecl (old_stmt) : 0);
if (old_decl && fndecl_built_in_p (old_decl))
{
/* Folding builtins can create multiple instructions,
we need to look at all of them. */
gimple_stmt_iterator i2 = gsi;
gsi_prev (&i2);
if (fold_stmt (&gsi))
{
gimple *new_stmt;
/* If a builtin at the end of a bb folded into nothing,
the following loop won't work. */
if (gsi_end_p (gsi))
{
cgraph_update_edges_for_call_stmt (old_stmt,
old_decl, NULL);
break;
}
if (gsi_end_p (i2))
i2 = gsi_start_bb (dest);
else
gsi_next (&i2);
while (1)
{
new_stmt = gsi_stmt (i2);
update_stmt (new_stmt);
cgraph_update_edges_for_call_stmt (old_stmt, old_decl,
new_stmt);
if (new_stmt == gsi_stmt (gsi))
{
/* It is okay to check only for the very last
of these statements. If it is a throwing
statement nothing will change. If it isn't
this can remove EH edges. If that weren't
correct then because some intermediate stmts
throw, but not the last one. That would mean
we'd have to split the block, which we can't
here and we'd loose anyway. And as builtins
probably never throw, this all
is mood anyway. */
if (maybe_clean_or_replace_eh_stmt (old_stmt,
new_stmt))
bitmap_set_bit (to_purge, dest->index);
break;
}
gsi_next (&i2);
while (1)
{
new_stmt = gsi_stmt (i2);
update_stmt (new_stmt);
cgraph_update_edges_for_call_stmt (old_stmt, old_decl,
new_stmt);
}
}
}
else if (fold_stmt (&gsi))
{
/* Re-read the statement from GSI as fold_stmt() may
have changed it. */
gimple *new_stmt = gsi_stmt (gsi);
update_stmt (new_stmt);
if (new_stmt == gsi_stmt (gsi))
{
/* It is okay to check only for the very last
of these statements. If it is a throwing
statement nothing will change. If it isn't
this can remove EH edges. If that weren't
correct then because some intermediate stmts
throw, but not the last one. That would mean
we'd have to split the block, which we can't
here and we'd loose anyway. And as builtins
probably never throw, this all
is mood anyway. */
if (maybe_clean_or_replace_eh_stmt (old_stmt,
new_stmt))
bitmap_set_bit (to_purge, first);
break;
}
gsi_next (&i2);
}
}
}
else if (fold_stmt (&gsi))
{
/* Re-read the statement from GSI as fold_stmt() may
have changed it. */
gimple *new_stmt = gsi_stmt (gsi);
update_stmt (new_stmt);
if (is_gimple_call (old_stmt)
|| is_gimple_call (new_stmt))
cgraph_update_edges_for_call_stmt (old_stmt, old_decl,
new_stmt);
if (is_gimple_call (old_stmt)
|| is_gimple_call (new_stmt))
cgraph_update_edges_for_call_stmt (old_stmt, old_decl,
new_stmt);
if (maybe_clean_or_replace_eh_stmt (old_stmt, new_stmt))
bitmap_set_bit (to_purge, dest->index);
}
}
if (maybe_clean_or_replace_eh_stmt (old_stmt, new_stmt))
bitmap_set_bit (to_purge, first);
}
if (EDGE_COUNT (dest->succs) > 0)
{
/* Avoid warnings emitted from folding statements that
became unreachable because of inlined function parameter
propagation. */
e = find_taken_edge (dest, NULL_TREE);
if (e)
stack.quick_push (e);
else
{
edge_iterator ei;
FOR_EACH_EDGE (e, ei, dest->succs)
stack.safe_push (e);
}
}
}
}
gimple_purge_all_dead_eh_edges (to_purge);
}
@ -5404,6 +5435,13 @@ optimize_inline_calls (tree fn)
gcc_assert (e->inline_failed);
}
/* If we didn't inline into the function there is nothing to do. */
if (!inlined_p)
{
delete id.statements_to_fold;
return 0;
}
/* Fold queued statements. */
update_max_bb_count ();
fold_marked_statements (last, id.statements_to_fold);
@ -5426,10 +5464,6 @@ optimize_inline_calls (tree fn)
gcc_assert (!id.debug_stmts.exists ());
/* If we didn't inline into the function there is nothing to do. */
if (!inlined_p)
return 0;
/* Renumber the lexical scoping (non-code) blocks consecutively. */
number_blocks (fn);