[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[muecker at gwdg dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

--- Comment #8 from Martin Uecker  ---
https://gcc.gnu.org/pipermail/gcc-patches/2023-February/611562.html

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[muecker at gwdg dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

--- Comment #7 from Martin Uecker  ---


* gimplify_type_size does not recurse into pointer, record, or function types
(the later are not mentioned). 

* the C FE has code to emit fake TYPE_DECLs for pointer types in
c-decl.cc/grokdeclarator 

* In the FE, size expressions in parameters go into pending_sizes and emitted
at a start of a function c-decl.cc/store_parm_decls

* function.cc/gimplify_parm_type only considers types with non-constant size
and otherwise recurses only into pointer types


How all this fits together is a bit of mystery to me. 

Modifying gimplify_parm_type to also recurse into function types seems to fix
this bug (and PR107557) but I am not sure if this is the right fix. Then there
should also be similar missing cases related to records/unions?

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[muecker at gwdg dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

--- Comment #6 from Martin Uecker  ---
Actually, I meant PR84305 for C.

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[muecker at gwdg dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

--- Comment #5 from Martin Uecker  ---
Probably related to PR88256

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[muecker at gwdg dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

--- Comment #4 from Martin Uecker  ---

The specific problem is triggered by the change to pointer_int_sum in
gcc/c-family/c-common.cc, but the underlying problem is older. The following
example fails since gcc 7:

void f(int n, int (*a(void))[n])
{
sizeof (*a());
}

int (*a(void))[1];

void g(void)
{
f(1, a);
}


https://godbolt.org/z/645ahfrzx

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[muecker at gwdg dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

--- Comment #3 from Martin Uecker  ---
Smaller example:

void f(int n, int (*a(void))[n])
{
(a())[0];
}

void g(void)
{
int (*a(void))[1];
f(1, a);
}

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining since r12-5338-g4e6bf0b9dd5585df

[marxin at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

Martin Liška  changed:

   What|Removed |Added

Summary|[12/13 Regression] ICE in   |[12/13 Regression] ICE in
   |make_ssa_name_fn with VLA   |make_ssa_name_fn with VLA
   |types in arguments and  |types in arguments and
   |inlining|inlining since
   ||r12-5338-g4e6bf0b9dd5585df
 CC||marxin at gcc dot gnu.org,
   ||muecker at gwdg dot de

--- Comment #2 from Martin Liška  ---
Started with r12-5338-g4e6bf0b9dd5585df.

[Bug c/108423] [12/13 Regression] ICE in make_ssa_name_fn with VLA types in arguments and inlining

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108423

Richard Biener  changed:

   What|Removed |Added

  Component|middle-end  |c
 Status|UNCONFIRMED |NEW
 Ever confirmed|0   |1
   Priority|P3  |P2
   Last reconfirmed||2023-01-17

--- Comment #1 from Richard Biener  ---
#3  0x01697500 in remap_ssa_name (name=, 
id=0x7fffd910) at /home/rguenther/src/trunk/gcc/tree-inline.cc:237
237   new_tree = make_ssa_name (remap_type (TREE_TYPE (name), id));
(gdb) p debug_tree (name)
 
nothrow
def_stmt 
version:1 in-free-list>
$1 = void

so another case with a missing/misplaced DECL_EXPR for the VLA size.