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tree-optimization/112444 - avoid bougs PHI value-numbering

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With .DEFERRED_INIT ssa_undefined_value_p () can return true for
values we did not visit (because they proved unreachable) but
are not .VN_TOP.  Avoid using those as value which, because they
are not visited, are assumed to be defined outside of the region.

	PR tree-optimization/112444
	* tree-ssa-sccvn.cc (visit_phi): Avoid using not visited
	defs as undefined vals.

	* gcc.dg/torture/pr112444.c: New testcase.
This commit is contained in:
Richard Biener 2023-11-09 09:41:10 +01:00
parent a0273d257c
commit 8ebcea91e2
2 changed files with 79 additions and 2 deletions
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65
gcc/testsuite/gcc.dg/torture/pr112444.c Normal file
View file

@ -0,0 +1,65 @@
/* { dg-do compile } */
/* { dg-additional-options "-ftrivial-auto-var-init=zero" } */
int qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_offset,
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_init_offset,
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_error,
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_phonebooks_i;
int g_string_new(), g_string_append_len(), qmi_message_tlv_read_guint8();
void qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message() {
int printable = g_string_new();
for (;;) {
{
if (__builtin_expect(({
int _g_boolean_var_4;
if (printable)
_g_boolean_var_4 = 1;
else
_g_boolean_var_4 = 0;
_g_boolean_var_4;
}),
0))
g_string_append_len();
}
unsigned char tmp;
qmi_message_tlv_read_guint8(
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_init_offset,
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_offset,
tmp,
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_error);
{
{
if (__builtin_expect(({
int _g_boolean_var_4;
if (printable)
_g_boolean_var_4 = 1;
else
_g_boolean_var_4 = 0;
_g_boolean_var_4;
}),
0))
g_string_append_len();
}
}
for (
;
qmi_message_pbm_get_all_capabilities_output_capability_basic_information_get_printable_message_phonebooks_i;) {
unsigned char tmp;
qmi_message_tlv_read_guint8(&tmp);
{
if (__builtin_expect(({
int _g_boolean_var_4;
if (printable)
_g_boolean_var_4 = 1;
else
_g_boolean_var_4 = 0;
_g_boolean_var_4;
}),
0))
g_string_append_len();
}
}
}
}

16
gcc/tree-ssa-sccvn.cc
View file

@ -5911,6 +5911,7 @@ static bool
visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
{
tree result, sameval = VN_TOP, seen_undef = NULL_TREE;
bool seen_undef_visited = false;
tree backedge_val = NULL_TREE;
bool seen_non_backedge = false;
tree sameval_base = NULL_TREE;
@ -5941,10 +5942,12 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
if (def == PHI_RESULT (phi))
continue;
++n_executable;
bool visited = true;
if (TREE_CODE (def) == SSA_NAME)
{
tree val = SSA_VAL (def, &visited);
if (!backedges_varying_p || !(e->flags & EDGE_DFS_BACK))
def = SSA_VAL (def);
def = val;
if (e->flags & EDGE_DFS_BACK)
backedge_val = def;
}
@ -5956,7 +5959,16 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
else if (TREE_CODE (def) == SSA_NAME
&& ! virtual_operand_p (def)
&& ssa_undefined_value_p (def, false))
seen_undef = def;
{
if (!seen_undef
/* Avoid having not visited undefined defs if we also have
a visited one. */
|| (!seen_undef_visited && visited))
{
seen_undef = def;
seen_undef_visited = visited;
}
}
else if (sameval == VN_TOP)
{
sameval = def;