https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65534
Bug ID: 65534
Summary: tailcall not optimized away
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: aldot at gcc dot gnu.org
CC: hubicka at ucw dot cz, rguenth at gcc dot gnu.org
Maybe this could be optimized by a thunk or by creating the alias automatically
or the like? Or is tailcall supposed to do this already?
trunk@221345
$ gcc -Os -c missed-opt.c -o missed-opt.plain.o
$ gcc -Os -c missed-opt.c -o missed-opt.manual.o -DOPTIMIZE_MANUALLY
$ size missed-opt.*.o
text data bss dec hex filename
86 0 0 86 56 missed-opt.manual.o
104 0 0 104 68 missed-opt.plain.o
$ cat missed-opt.c ; echo EOF
static int fd = -1;
extern void dummy0(void);
extern void dummy1(int);
extern void setutent(void) __attribute__ ((__nothrow__ ));
extern __typeof (setutent) setutent __asm__ ("" "__GI_setutent")
__attribute__ ((visibility ("hidden")));
extern void getutent(void) __attribute__ ((__nothrow__ ));
extern __typeof (getutent) getutent __asm__ ("" "__GI_getutent")
__attribute__ ((visibility ("hidden")));
static void __setutent_unlocked(void) {
if (fd < 0) {
dummy0();
if (fd < 0) {
dummy0();
if (fd < 0)
return;
}
return;
}
dummy1(fd);
}
#ifndef OPTIMIZE_MANUALLY
void setutent(void) {
((void)0);
__setutent_unlocked();
((void)0);
}
#else
extern __typeof (__setutent_unlocked) setutent
__attribute__ ((alias ("__setutent_unlocked")));
#endif
extern __typeof (setutent) __EI_setutent __asm__("" "setutent");
extern __typeof (setutent) __EI_setutent
__attribute__((alias ("" "__GI_setutent")));
static void __getutent_unlocked(void) {
if (fd < 0)
__setutent_unlocked();
}
#ifndef OPTIMIZE_MANUALLY
void getutent(void) {
((void)0);
__getutent_unlocked();
((void)0);
}
#else
extern __typeof (__getutent_unlocked) getutent
__attribute__ ((alias ("__getutent_unlocked")));
#endif
extern __typeof (getutent) __EI_getutent __asm__("" "getutent");
extern __typeof (getutent) __EI_getutent
__attribute__((alias ("" "__GI_getutent")));
EOF
