https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118779
Bug ID: 118779
Summary: [15 Regression] clisp miscompilation since r15-580
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jakub at gcc dot gnu.org
Target Milestone: ---
Created attachment 60409
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60409&action=edit
package.i
clisp package.c seems to be miscompiled since
r15-580-gf3e5f4c58591f5dacdd14a65ec47bbe310df02a0
/opt/notnfs/gcc-bisect/obj/gcc/cc1.r15-579 -quiet -fexceptions -fpie
-fstack-protector-strong -m64 -march=x86-64 -mtune=generic
-fstack-clash-protection -fcf-protection -mtls-dialect=gnu2
-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -O -fwrapv
-fno-strict-aliasing package.i -std=gnu2x -fdump-tree-dom3-details-folding
-fdump-tree-slsr
vs.
/opt/notnfs/gcc-bisect/obj/gcc/cc1.r15-580 -quiet -fexceptions -fpie
-fstack-protector-strong -m64 -march=x86-64 -mtune=generic
-fstack-clash-protection -fcf-protection -mtls-dialect=gnu2
-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -O -fwrapv
-fno-strict-aliasing package.i -std=gnu2x -fdump-tree-dom3-details-folding
-fdump-tree-slsr
has identical slsr dump but in dom3 I see only in the r15-580 dump in
rehash_symtab function (noinline added by me, but it still reproduces with
that).
Applying pattern match.pd:7200, generic-match-6.cc:1457
[6] Registering jump thread: (13, 14) incoming edge; (14, 18) normal;
where match.pd:7200 at that revision was
98998245d99f (Richard Biener 2016-04-29 08:36:49 +0000 7194) /*
Simplify pointer equality compares using PTA. */
98998245d99f (Richard Biener 2016-04-29 08:36:49 +0000 7195) (for
neeq (ne eq)
98998245d99f (Richard Biener 2016-04-29 08:36:49 +0000 7196)
(simplify
98998245d99f (Richard Biener 2016-04-29 08:36:49 +0000 7197) (neeq
@0 @1)
98998245d99f (Richard Biener 2016-04-29 08:36:49 +0000 7198) (if
(POINTER_TYPE_P (TREE_TYPE (@0))
98998245d99f (Richard Biener 2016-04-29 08:36:49 +0000 7199)
&& ptrs_compare_unequal (@0, @1))
f913ff2adc41 (Thomas Koenig 2018-04-07 23:52:03 +0000 7200) {
constant_boolean_node (neeq != EQ_EXPR, type); })))
_126 = (unsigned int) _9;
_127 = _126 + 4294967295;
_128 = (sizetype) _127;
_129 = _128 + 1;
_130 = _129 * 8;
_131 = (void * *) _130;
...
<bb 7> [local count: 738197516]:
# offset_66 = PHI <0B(6), offset_101(9)>
...
offset_101 = offset_66 + 8;
if (offset_101 != _131)
...
_119 = (unsigned int) _9;
_120 = _119 + 4294967295;
_121 = (sizetype) _120;
_122 = _121 + 1;
_123 = _122 * 8;
_124 = (void * *) _123;
...
<bb 11> [local count: 738197528]:
# offset_69 = PHI <0B(10), offset_108(14)>
...
offset_108 = offset_69 + 8;
if (offset_108 != _124)
bb 7 is one loop, bb 11 is another.
Now, _131 and _124 to me look to be the same thing.
In the source, those 2 loops are
{
{ gcv_object_t* offset = 0;
{ uintWL count = oldsize;
do {
{ object oldentry =
*(gcv_object_t*)(((UBYTE*)(&((Svector)((oint)(((STACK[-1-(sintP)(2)])))-1UL))->data[0])+((aint)offset))
);
if ((((oint)(oldentry) & 7) == (3UL +0)))
do {
((STACK[-1-(sintP)(-1)]) = ((((Cons)((oint)(oldentry)-3UL))->cdr)),
STACK -= -1);
(((Cons)((oint)(oldentry)-3UL))->cdr) = ((STACK[-1-(sintP)(2)]));
((STACK[-1-(sintP)(2)])) = oldentry;
newinsert((((Cons)((oint)(oldentry)-3UL))->car),newsize);
oldentry = (STACK -= 1, (STACK[-1-(sintP)(-1)]));
} while ((((oint)(oldentry) & 7) == (3UL +0)));
offset++;
}} while (--count);
}}}
{
{ gcv_object_t* offset = 0;
{ uintWL count;
do { if (!(sizeof(count)==sizeof(uintL))) {
dotimes_called_with_count_of_wrong_size(); }; { count = (oldsize); do {{ {
object oldentry =
*(gcv_object_t*)(((UBYTE*)(&((Svector)((oint)(((STACK[-1-(sintP)(2)])))-1UL))->data[0])+((aint)offset)));
if (!((((oldentry) == (((object)((UBYTE*)(&symbol_tab_data.S_nil)+(1UL)))))) ||
(((oint)(oldentry) & 7) == (3UL +0)))) { ((STACK[-1-(sintP)(-1)]) = (oldentry),
STACK -= -1); newinsert(oldentry,newsize); (STACK -= (sintP)(1)); } offset++;
}}} while (--count != 0); }; } while(0)
# 224 "../src/package.d"
;
}}}
Arguably, maybe the 2 offset vars should have aint type and use offset+=sizeof
(gcv_object_t); instead of offset++.
