https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116054
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization, ra
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Before RA:
```
(call_insn 16 15 44 3 (parallel [
(set (reg:DI 10 a0)
(call (mem:SI (symbol_ref:SI ("_Z18esp_timer_get_timev") [flags
0x41] <function_decl 0x7399a835df00 esp_timer_get_time>) [0 esp_timer_get_time
S4 A32])
(const_int 0 [0])))
(use (unspec:SI [
(const_int 0 [0])
] UNSPEC_CALLEE_CC))
(clobber (reg:SI 1 ra))
]) "/app/example.cpp":18:33 355 {call_value_internal}
(expr_list:REG_CALL_DECL (symbol_ref:SI ("_Z18esp_timer_get_timev") [flags
0x41] <function_decl 0x7399a835df00 esp_timer_get_time>)
(nil))
(nil))
(insn 44 16 45 3 (set (reg:SI 141)
(reg:SI 10 a0)) "/app/example.cpp":18:33 211 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 10 a0)
(nil)))
(insn 45 44 46 3 (set (reg:SI 142 [+4 ])
(reg:SI 11 a1 [+4 ])) "/app/example.cpp":18:33 211 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 11 a1 [+4 ])
(nil)))
(insn 46 45 47 3 (set (subreg:SI (reg:DI 136 [ _7 ]) 0)
(reg:SI 141)) "/app/example.cpp":18:33 211 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 141)
(nil)))
(insn 47 46 18 3 (set (subreg:SI (reg:DI 136 [ _7 ]) 4)
(reg:SI 142 [+4 ])) "/app/example.cpp":18:33 211 {*movsi_internal}
(expr_list:REG_DEAD (reg:SI 142 [+4 ])
(nil)))
```
Afterwards:
```
(call_insn 16 15 46 3 (parallel [
(set (reg:DI 10 a0)
(call (mem:SI (symbol_ref:SI ("_Z18esp_timer_get_timev") [flags
0x41] <function_decl 0x775adc3adc00 esp_timer_get_time>) [0 esp_timer_get_time
S4 A32])
(const_int 0 [0])))
(use (unspec:SI [
(const_int 0 [0])
] UNSPEC_CALLEE_CC))
(clobber (reg:SI 1 ra))
]) "/app/example.cpp":18:33 431 {call_value_internal}
(expr_list:REG_CALL_DECL (symbol_ref:SI ("_Z18esp_timer_get_timev") [flags
0x41] <function_decl 0x775adc3adc00 esp_timer_get_time>)
(nil))
(nil))
(insn 46 16 47 3 (set (reg:SI 18 s2 [orig:136 _7 ] [136])
(reg:SI 10 a0 [141])) "/app/example.cpp":18:33 276 {*movsi_internal}
(nil))
(insn 47 46 18 3 (set (reg:SI 19 s3 [ _7+4 ])
(reg:SI 11 a1 [orig:142+4 ] [142])) "/app/example.cpp":18:33 276
{*movsi_internal}
(nil))
```
Note in GCC 13 and before there was a clobber of reg pseduo 136 between insn
between insn 45 and 46 (in the before RA) which seems to allow the RA to be
better in this case.
