https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78837
Bug ID: 78837
Summary: missing -Walloca-larger-than on a call in a ternary
expression
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
Both -Walloca-larger-than and -Walloc-larger-than fail to diagnose calls where
the called function is the result of a ternary operator, as in (n < 123 ?
alloca : malloc)(n):
$ cat d.c && gcc -O2 -S -Walloca-larger-than=10 -Walloc-size-larger-than=10 d.c
void f0 (void*);
void f1 (unsigned n)
{
void *p;
if (n < 32)
n = 32;
if (n < 123)
p = __builtin_alloca (n);
else
p = __builtin_malloc (n);
f0 (p);
}
void f2 (unsigned n)
{
if (n < 32)
n = 32;
void *p = (123 < n ? __builtin_malloc: __builtin_alloca)(n); // missing
warning
f0 (p);
}
d.c: In function ‘f1’:
d.c:11:7: warning: argument to ‘alloca’ may be too large
[-Walloca-larger-than=]
p = __builtin_alloca (n);
~~^~~~~~~~~~~~~~~~~~~~~~
d.c:11:7: note: limit is 10 bytes, but argument may be as large as 122
d.c:13:7: warning: argument 1 range [32, 4294967295] exceeds maximum object
size 10 [-Walloc-size-larger-than=]
p = __builtin_malloc (n);
~~^~~~~~~~~~~~~~~~~~~~~~
d.c:13:7: note: in a call to built-in allocation function ‘__builtin_malloc’
