[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031 --- Comment #13 from Sergei Trofimovich --- The change also fixed original nix-2.4 test failure. Thank you!
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031 Jakub Jelinek changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #12 from Jakub Jelinek --- Fixed now.
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031 --- Comment #11 from CVS Commits --- The master branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:aeca44768d54b089243004d1ef00d34dfa9f6530 commit r12-6643-gaeca44768d54b089243004d1ef00d34dfa9f6530 Author: Jakub Jelinek Date: Mon Jan 17 18:10:34 2022 +0100 c++: Fix cp_genericize_target_expr for TARGET_EXPRs created for global initialization [PR104031] The following patch is miscompiled, cp_genericize_target_expr expects that for the constant part split_nonconstant_init will emit an INIT_EXPR that will initialize it, but that doesn't happen and instead we get DECL_INITIAL on the TARGET_EXPR_SLOT that isn't initialized anywhere in the IL. The problem is that the TARGET_EXPR has been created while current_function_decl was NULL, it is inside a global var initializer. That means the build_local_temp created VAR_DECL has NULL DECL_CONTEXT. Later on when genericizing the ssdf (current_function_decl is already non-NULL), the new cp_genericize_target_expr is called and during split_nonconstant_init it checks is_local_temp, but that due to the NULL DECL_CONTEXT returns false. DECL_CONTEXT is set only later on during gimplification. The following patch fixes it by setting DECL_CONTEXT also inside of cp_genericize_target_expr, which fixes the testcase. But if there are better spots to do that, please let me know... 2022-01-17 Jakub Jelinek PR c++/104031 * cp-gimplify.c (cp_genericize_target_expr): Set DECL_CONTEXT of TARGET_EXPR_SLOT to current_function_decl if it was NULL. * g++.dg/cpp1y/pr104031.C: New test.
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031 --- Comment #10 from Andrew Pinski --- (In reply to Jakub Jelinek from comment #8) > That last testcase isn't very good for the testsuite, because 0 is pretty > common value on the stack, so even without the store the chances that it > will be already zero are high. Yes I didn't think of that while reducing it further. But that explains why it would pass at -O0 really :)
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031 --- Comment #9 from Jakub Jelinek --- Created attachment 52208 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52208=edit gcc12-pr104031.patch This seems to work for the testcase, but dunno if there aren't better fixes.
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
--- Comment #8 from Jakub Jelinek ---
That last testcase isn't very good for the testsuite, because 0 is pretty
common value on the stack, so even without the store the chances that it will
be already zero are high.
42 is less likely...
// PR c++/104031
// { dg-do run { target c++14 } }
// { dg-options "-O2" }
struct A {
A () {}
~A () {}
};
struct B {
A a;
int b = 0;
};
struct C
{
[[gnu::noipa]]
C (B x) { if (x.b != 42) __builtin_abort (); }
};
static C c ({ .a = A{}, .b = 42 });
int
main ()
{
}
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment #7 from Jakub Jelinek ---
My guess is that the problem is that when the TARGET_EXPR_SLOT is created using
build_local_temp, current_function_decl is NULL, it is in s_op global namespace
var initializer.
Eventually we add it to ssdf and call in the new r12-6329 spot
split_nonconstant_init, which has:
743 if (VAR_P (dest) && !is_local_temp (dest))
744 {
745 DECL_INITIAL (dest) = init;
746 TREE_READONLY (dest) = 0;
747 }
but due to the still unchanged DECL_CONTEXT being NULL is_local_temp returns
false and we set DECL_INITIAL instead of what the code expects.
The temporary gets DECL_CONTEXT set only during gimplification.
So, I think either we should fill in TARGET_EXPR_SLOT's DECL_CONTEXT when we
are adding those exprs into ssdf, or the r12-6329 code should ensure the slot
has non-NULL DECL_CONTEXT if current_function_decl or something similar.
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
--- Comment #6 from Sergei Trofimovich ---
> void __static_initialization_and_destruction_0 (int __initialize_p, int
> __priority)
> {
> struct InfoD.2399 D.2453 = {.arityD.2402=0};
Having poked at -fdump-tree-all-raw I now think `= {.arityD.2402=0};` is not a
variable initialization itself, but a reference to `DECL_INITIAL` that would do
an initialization.
Perhaps something was supposed to expand this `DECL_INITIAL` to an actual
initializing statement, but did not for this case.
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
--- Comment #5 from Sergei Trofimovich ---
gcc-11 for comparison did not seem to have `struct InfoD.2399 D.2453 =
{.arityD.2402=0};` style nodes and encoded stores explicitly:
main.cc.244t.optimized:
voidD.48 _GLOBAL__sub_I_main ()
{
struct InfoD.2377 D.2496;
...
D.2496.arityD.2380 = 0;
and produced expected RTL: main.cc.245r.expand:
;; Function _GLOBAL__sub_I_main (_GLOBAL__sub_I_main, funcdef_no=14,
decl_uid=2463, cgraph_uid=15, symbol_order=15) (executed once)
...
;;
;; Full RTL generated for this function:
;;
1: NOTE_INSN_DELETED
3: NOTE_INSN_BASIC_BLOCK 2
2: NOTE_INSN_FUNCTION_BEG
5: [r77:DI-0x4]=0 // <<<--- our lost store
6: {r82:DI=r77:DI-0x8;clobber flags:CC;}
7: si:DI=r82:DI
8: di:DI=`_ZL4s_op'
9: call [`_ZN14RegisterPrimOpC1E4Info'] argc:0
REG_CALL_DECL `_ZN14RegisterPrimOpC1E4Info'
REG_EH_REGION 0
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
--- Comment #4 from Sergei Trofimovich ---
Great test, Andrew!
Something is completely dropped initialization of Info{} input argument to
s_op. As if it's lifetime ends before RegisterPrimOp{} enters:
--- main.s.good 2022-01-14 21:53:42.334571321 +
+++ main.s.bad 2022-01-14 21:53:51.275722971 +
@@ -43,26 +43,25 @@
.p2align 4
.type _GLOBAL__sub_I_main, @function
_GLOBAL__sub_I_main:
.LFB14:
.cfi_startproc
subq$24, %rsp #,
.cfi_def_cfa_offset 32
# ../main.cc:21: });
movl$_ZL4s_op, %edi #,
leaq8(%rsp), %rsi #, tmp84
- movl$0, 12(%rsp)#, D.2496.arityD.2380
call_ZN14RegisterPrimOpC1E4Info #
# ../main.cc:22: int main() {}
addq$24, %rsp #,
.cfi_def_cfa_offset 8
ret
.cfi_endproc
.LFE14:
.size _GLOBAL__sub_I_main, .-_GLOBAL__sub_I_main
.section.init_array,"aw"
.align 8
.quad _GLOBAL__sub_I_main
.local _ZL4s_op
.comm _ZL4s_op,1,1
- .ident "GCC: (GNU) 11.2.0"
+ .ident "GCC: (GNU) 12.0.0 20220109 (experimental)"
.section.note.GNU-stack,"",@progbits
Initial gimple looks valid to me: main.cc.006t.gimple:
void __static_initialization_and_destruction_0 (int __initialize_p, int
__priority)
{
struct InfoD.2399 D.2453 = {.arityD.2402=0};
...
_ZN6vectorC1EvD.2377 ();
...
try { try { try {
# USE = anything
# CLB = anything
_ZN14RegisterPrimOpC1E4InfoD.2413 (_opD.2424, );
} finally {
# USE = anything
# CLB = anything
_ZN4InfoD1EvD.2457 ();
} } finally {
D.2453 = {CLOBBER};
}
Final tree also looks ok: main.cc.250t.optimized:
voidD.48 _GLOBAL__sub_I_mainD.2486 ()
{
struct InfoD.2399 D.2522 = {.arityD.2402=0};
# USE = nonlocal escaped { D.2424 D.2522 } (nonlocal, escaped)
# CLB = nonlocal escaped { D.2424 D.2522 } (nonlocal, escaped)
_ZN14RegisterPrimOpC1E4InfoD.2413 (&_ZL4s_opD.2424, );
D.2522 ={v} {CLOBBER};
First RTL seems to lack the assignment: main.cc.252r.expand:
;; Function _GLOBAL__sub_I_main (_GLOBAL__sub_I_main, funcdef_no=14,
decl_uid=2486, cgraph_uid=15, symbol_order=15) (executed once)
...
;;
;; Full RTL generated for this function:
;;
1: NOTE_INSN_DELETED
3: NOTE_INSN_BASIC_BLOCK 2
2: NOTE_INSN_FUNCTION_BEG
5: {r82:DI=r77:DI-0x8;clobber flags:CC;}
6: si:DI=r82:DI
7: di:DI=`_ZL4s_op'
8: call [`_ZN14RegisterPrimOpC1E4Info'] argc:0
REG_CALL_DECL `_ZN14RegisterPrimOpC1E4Info'
REG_EH_REGION 0
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
--- Comment #3 from Andrew Pinski ---
Reduced testcase without any headers:
struct vector
{
vector(){} ~vector(){}
};
struct Info {
vector args;
int arity = 0;
};
struct RegisterPrimOp
{
[[gnu::noipa, gnu::noinline]]
RegisterPrimOp(Info info) {
if (info.arity != 0)
__builtin_trap();
}
};
static RegisterPrimOp s_op({
.args = vector{},
.arity = 0,
});
int main() {}
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031
--- Comment #2 from Andrew Pinski ---
I can remove std::string but not figure out how to remove std::vector yet:
#include
#include
struct string
{
string(int){}
};
struct allocator
{
allocator(){}
};
struct vector
{
vector(allocator t = allocator{}){}
vector(string, allocator t = allocator{}){}
vector(std::initializer_list&, allocator t = allocator{}){}
};
#if 1
typedef std::vector t;
#else
typedef vector t;
#endif
struct Info {
t args;
int arity;
};
struct RegisterPrimOp
{
RegisterPrimOp(Info && info) __attribute__((noipa, noinline)) {
if (info.arity != 0)
__builtin_trap();
}
};
static RegisterPrimOp s_op({
.args = {1},
.arity = 0,
});
int main() {}
[Bug c++/104031] [12 regression] Global nested constructors generate invalid code since r12-6329-g4f6bc28fc7dd86bd
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104031 Martin Liška changed: What|Removed |Added Last reconfirmed||2022-01-14 Ever confirmed|0 |1 Target Milestone|--- |12.0 Summary|[12 regression] Global |[12 regression] Global |nested constructors |nested constructors |generate invalid code. |generate invalid code since ||r12-6329-g4f6bc28fc7dd86bd Status|UNCONFIRMED |NEW Priority|P3 |P1 CC||jason at gcc dot gnu.org, ||marxin at gcc dot gnu.org Keywords||wrong-code --- Comment #1 from Martin Liška --- Also started with r12-6329-g4f6bc28fc7dd86bd.
