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middle-end/40635 - SSA update losing PHI arg loations

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The following fixes an issue where SSA update loses PHI argument
locations when updating PHI nodes it didn't create as part of the
SSA update.  For the case where the reaching def is the same as
the current argument opt to do nothing and for the case where the
PHI argument already has a location keep that (that's an indication
the PHI node wasn't created as part of the update SSA process).

	PR middle-end/40635
	* tree-into-ssa.cc (rewrite_update_phi_arguments): Only
	update the argument when the reaching definition is different
	from the current argument.  Keep an existing argument
	location.

	* gcc.dg/uninit-pr40635.c: New testcase.

(cherry picked from commit 0d14720f93)
This commit is contained in:
Richard Biener 2022-12-05 16:03:21 +01:00
parent 1edc6a71fe
commit 844ff32c04
2 changed files with 40 additions and 4 deletions
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33
gcc/testsuite/gcc.dg/uninit-pr40635.c Normal file
View File

@ -0,0 +1,33 @@
/* { dg-do compile } */
/* { dg-options "-O -Wuninitialized" } */
struct hostent {
char **h_addr_list;
};
struct hostent *gethostbyname(const char*);
int socket(void);
int close(int);
int connect(int, const char*);
int get_tcp_socket(const char *machine)
{
struct hostent *hp;
int s42, x;
char **addr;
hp = gethostbyname(machine);
x = 0;
for (addr = hp->h_addr_list; *addr; addr++)
{
s42 = socket();
if (s42 < 0)
return -1;
x = connect(s42, *addr);
if (x == 0)
break;
close(s42);
}
if (x < 0)
return -1;
return s42; /* { dg-warning "uninitialized" } */
}

11
gcc/tree-into-ssa.cc
View File

@ -2107,7 +2107,6 @@ rewrite_update_phi_arguments (basic_block bb)
symbol we may find NULL arguments. That's why we
take the symbol from the LHS of the PHI node. */
reaching_def = get_reaching_def (lhs_sym);
}
else
{
@ -2119,8 +2118,9 @@ rewrite_update_phi_arguments (basic_block bb)
reaching_def = get_reaching_def (arg);
}
/* Update the argument if there is a reaching def. */
if (reaching_def)
/* Update the argument if there is a reaching def different
from arg. */
if (reaching_def && reaching_def != arg)
{
location_t locus;
int arg_i = PHI_ARG_INDEX_FROM_USE (arg_p);
@ -2130,6 +2130,10 @@ rewrite_update_phi_arguments (basic_block bb)
/* Virtual operands do not need a location. */
if (virtual_operand_p (reaching_def))
locus = UNKNOWN_LOCATION;
/* If SSA update didn't insert this PHI the argument
might have a location already, keep that. */
else if (gimple_phi_arg_has_location (phi, arg_i))
locus = gimple_phi_arg_location (phi, arg_i);
else
{
gimple *stmt = SSA_NAME_DEF_STMT (reaching_def);
@ -2147,7 +2151,6 @@ rewrite_update_phi_arguments (basic_block bb)
gimple_phi_arg_set_location (phi, arg_i, locus);
}
if (e->flags & EDGE_ABNORMAL)
SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1;
}