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tree-optimization/113796 - if-conversion and ranges

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The following makes sure to wipe range info before folding the
COND_EXPRs we insert as part of replacing PHI nodes when combining
blocks in the if-conversion pass.

	PR tree-optimization/113796
	* tree-if-conv.cc (combine_blocks): Wipe range-info before
	replacing PHIs and inserting predicates.

	* gcc.dg/torture/pr113796.c: New testcase.
This commit is contained in:
Richard Biener 2024-02-07 13:08:43 +01:00
parent 9920057309
commit 8636c538b6
2 changed files with 41 additions and 16 deletions
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16
gcc/testsuite/gcc.dg/torture/pr113796.c Normal file
View file

@ -0,0 +1,16 @@
/* { dg-do run } */
/* { dg-additional-options "-ftree-loop-if-convert -fno-vect-cost-model" } */
signed char a[] = {0x80, 0x80,0x80,0x80};
int b;
signed char c;
int main()
{
for (; b < sizeof(a); b += 1)
c = a[b] < 0 ?: a[b] >> 6;
if (c != 1)
__builtin_abort ();
return 0;
}

41
gcc/tree-if-conv.cc
View file

@ -2909,6 +2909,29 @@ combine_blocks (class loop *loop, bool loop_versioned)
edge e;
edge_iterator ei;
/* Reset flow-sensitive info before predicating stmts or PHIs we
might fold. */
bool *predicated = XNEWVEC (bool, orig_loop_num_nodes);
for (i = 0; i < orig_loop_num_nodes; i++)
{
bb = ifc_bbs[i];
predicated[i] = is_predicated (bb);
if (predicated[i])
{
for (auto gsi = gsi_start_phis (bb);
!gsi_end_p (gsi); gsi_next (&gsi))
reset_flow_sensitive_info (gimple_phi_result (*gsi));
for (auto gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple *stmt = gsi_stmt (gsi);
ssa_op_iter i;
tree op;
FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
reset_flow_sensitive_info (op);
}
}
}
remove_conditions_and_labels (loop);
insert_gimplified_predicates (loop);
predicate_all_scalar_phis (loop, loop_versioned);
@ -2917,20 +2940,13 @@ combine_blocks (class loop *loop, bool loop_versioned)
predicate_statements (loop);
/* Merge basic blocks. */
exit_bb = NULL;
bool *predicated = XNEWVEC (bool, orig_loop_num_nodes);
exit_bb = single_exit (loop)->src;
gcc_assert (exit_bb != loop->latch);
for (i = 0; i < orig_loop_num_nodes; i++)
{
bb = ifc_bbs[i];
predicated[i] = !is_true_predicate (bb_predicate (bb));
free_bb_predicate (bb);
if (bb_with_exit_edge_p (loop, bb))
{
gcc_assert (exit_bb == NULL);
exit_bb = bb;
}
}
gcc_assert (exit_bb != loop->latch);
merge_target_bb = loop->header;
@ -3003,13 +3019,6 @@ combine_blocks (class loop *loop, bool loop_versioned)
/* If this is the first load we arrive at update last_vdef
so we handle stray PHIs correctly. */
last_vdef = gimple_vuse (stmt);
if (predicated[i])
{
ssa_op_iter i;
tree op;
FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
reset_flow_sensitive_info (op);
}
}
/* Update stmt list. */