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c-family: Avoid ICE on va_arg [PR99324]

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build_va_arg calls the middle-end mark_addressable, which e.g. requires that
cfun is non-NULL.  The following patch calls instead c_common_mark_addressable_vec
which is the c-family variant similarly to the FE c_mark_addressable and
cxx_mark_addressable, except that it doesn't error on addresses of register
variables.  As the taking of the address is artificial for the .VA_ARG
ifn and when that is lowered goes away, it is similar case to the vector
subscripting for which c_common_mark_addressable_vec has been added.

2021-03-03  Jakub Jelinek  <jakub@redhat.com>

	PR c/99324
	* c-common.c (build_va_arg): Call c_common_mark_addressable_vec
	instead of mark_addressable.  Fix a comment typo -
	neutrallly -> neutrally.

	* gcc.c-torture/compile/pr99324.c: New test.
This commit is contained in:
Jakub Jelinek 2021-03-03 09:55:19 +01:00
parent b5040344b9
commit ba09d11a9d
2 changed files with 22 additions and 3 deletions
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6
gcc/c-family/c-common.c
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@ -4553,7 +4553,7 @@ build_va_arg (location_t loc, tree expr, tree type)
if (canon_va_type == NULL_TREE)
error_at (loc, "first argument to %<va_arg%> not of type %<va_list%>");
/* Let's handle things neutrallly, if expr:
/* Let's handle things neutrally, if expr:
- has undeclared type, or
- is not an va_list type. */
return build_va_arg_1 (loc, type, error_mark_node);
@ -4565,7 +4565,7 @@ build_va_arg (location_t loc, tree expr, tree type)
/* Take the address, to get '&ap'. Note that &ap is not a va_list
type. */
mark_addressable (expr);
c_common_mark_addressable_vec (expr);
expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (expr)), expr);
return build_va_arg_1 (loc, type, expr);
@ -4627,7 +4627,7 @@ build_va_arg (location_t loc, tree expr, tree type)
/* Take the address, to get '&ap'. Make sure it's a pointer to array
elem type. */
mark_addressable (expr);
c_common_mark_addressable_vec (expr);
expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (canon_va_type)),
expr);

19
gcc/testsuite/gcc.c-torture/compile/pr99324.c Normal file
View File

@ -0,0 +1,19 @@
/* PR c/99324 */
#include <stdarg.h>
int
foo (int x, ...)
{
va_list a;
va_start (a, x);
int b[6] = {};
int bar (c)
int c[1][va_arg (a, int)];
{
return sizeof c[0];
}
int r = bar (b);
va_end (a);
return r;
}