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ifcvt: Do not lower bitfields if we can't analyze dr's [PR107275]

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The ifcvt dead code elimination code was not built to deal with inline
assembly, loops with such would never be if-converted in the past since we can't
do data-reference analysis on them and vectorization would eventually fail.  For
this reason we now also do not lower bitfields if the data-reference analysis
fails, as we would not end up vectorizing it.  As a consequence this also fixes
this PR as the dead code elimination will not run for such cases and wrongfully
eliminate inline assembly statements.

gcc/ChangeLog:

	PR tree-optimization/107275
	* tree-if-conv.cc (if_convertible_loop_p_1): Move
	find_data_references_in_loop call from here...
	(if_convertible_loop_p): And move data-reference vector initialization
	from here...
	(tree_if_conversion):... to here.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/pr107275.c: New test.
This commit is contained in:
Andre Vieira 2022-10-18 10:51:09 +01:00
parent a23225fb4f
commit aae016f99b
2 changed files with 30 additions and 15 deletions
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15
gcc/testsuite/gcc.dg/vect/pr107275.c Normal file
View file

@ -0,0 +1,15 @@
/* { dg-do compile } */
struct st
{
int a : 1;
};
void
foo (struct st *s, int n)
{
for (int i = 0; i < n; ++i)
{
s[i].a = i;
__asm__ __volatile__ ("":::"memory");
}
}

30
gcc/tree-if-conv.cc
View file

@ -1416,9 +1416,6 @@ if_convertible_loop_p_1 (class loop *loop, vec<data_reference_p> *refs)
basic_block exit_bb = NULL;
vec<basic_block> region;
if (find_data_references_in_loop (loop, refs) == chrec_dont_know)
return false;
calculate_dominance_info (CDI_DOMINATORS);
for (i = 0; i < loop->num_nodes; i++)
@ -1541,12 +1538,11 @@ if_convertible_loop_p_1 (class loop *loop, vec<data_reference_p> *refs)
- if its basic blocks and phi nodes are if convertible. */
static bool
if_convertible_loop_p (class loop *loop)
if_convertible_loop_p (class loop *loop, vec<data_reference_p> *refs)
{
edge e;
edge_iterator ei;
bool res = false;
vec<data_reference_p> refs;
/* Handle only innermost loop. */
if (!loop || loop->inner)
@ -1578,15 +1574,7 @@ if_convertible_loop_p (class loop *loop)
if (loop_exit_edge_p (loop, e))
return false;
refs.create (5);
res = if_convertible_loop_p_1 (loop, &refs);
data_reference_p dr;
unsigned int i;
for (i = 0; refs.iterate (i, &dr); i++)
free (dr->aux);
free_data_refs (refs);
res = if_convertible_loop_p_1 (loop, refs);
delete innermost_DR_map;
innermost_DR_map = NULL;
@ -3499,6 +3487,7 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
auto_vec <gassign *, 4> writes_to_lower;
bitmap exit_bbs;
edge pe;
vec<data_reference_p> refs;
again:
rloop = NULL;
@ -3508,6 +3497,7 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
need_to_predicate = false;
need_to_rewrite_undefined = false;
any_complicated_phi = false;
refs.create (5);
/* Apply more aggressive if-conversion when loop or its outer loop were
marked with simd pragma. When that's the case, we try to if-convert
@ -3537,11 +3527,14 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
goto cleanup;
}
if (find_data_references_in_loop (loop, &refs) == chrec_dont_know)
goto cleanup;
if (loop->num_nodes > 2)
{
need_to_ifcvt = true;
if (!if_convertible_loop_p (loop) || !dbg_cnt (if_conversion_tree))
if (!if_convertible_loop_p (loop, &refs) || !dbg_cnt (if_conversion_tree))
goto cleanup;
if ((need_to_predicate || any_complicated_phi)
@ -3658,6 +3651,13 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
todo |= TODO_cleanup_cfg;
cleanup:
data_reference_p dr;
unsigned int i;
for (i = 0; refs.iterate (i, &dr); i++)
free (dr->aux);
refs.truncate (0);
if (ifc_bbs)
{
unsigned int i;