https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87094
Bug ID: 87094
Summary: Suboptimal accounting for stack growth in inlining
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: amonakov at gcc dot gnu.org
CC: marxin at gcc dot gnu.org
Target Milestone: ---
On this small example:
void g(int, char *);
static void f(int x)
{
char c[2048];
g(x, c);
}
void h(int x)
{
f(x);
}
GCC does not inline f into h due to reaching stack growth limit. However, since
f is called unconditionally, the original stack growth is at least max(f_stack,
h_stack), and post-inlining stack growth is at most f_stack+h_stack.
Since h_stack is 0, both are equal and inlining should be considered.
If h called f only conditionally, avoiding inlining would be correct.
