https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103542
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Blocks| |56456
CC| |msebor at gcc dot gnu.org
--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
The IL for the function is below. It seems quite inefficient compared to GCC
9.
void get_default_config.part.0 (const uint32_t id)
{
uint32_t error;
uint32_t entry;
unsigned int _4;
uint32_t * _5;
<bb 2> [local count: 118111600]:
goto <bb 4>; [100.00%]
<bb 3> [local count: 955630225]:
entry_2 = entry_1 + 1;
<bb 4> [local count: 1073741824]:
# entry_1 = PHI <entry_2(3), 0(2)>
_4 = config[id_3(D)].num_apples;
if (entry_1 < _4)
goto <bb 3>; [89.00%]
else
goto <bb 5>; [11.00%]
<bb 5> [local count: 118111600]:
config[id_3(D)].num_apples = 0;
_5 = &config[id_3(D)].num_lemons;
switch (id_3(D)) <default: <L4> [20.00%], case 0: <L0> [20.00%], case 1: <L1>
[20.00%], case 2: <L2> [20.00%], case 3: <L3> [20.00%]>
<bb 6> [local count: 23622320]:
<L0>:
MEM <struct fruit_config[4]> [(uint32_t *)&config][0].num_lemons = 0;
goto <bb 11>; [100.00%]
<bb 7> [local count: 23622320]:
<L1>:
MEM <struct fruit_config[4]> [(uint32_t *)&config][1].num_lemons = 0;
goto <bb 11>; [100.00%]
<bb 8> [local count: 23622320]:
<L2>:
MEM <struct fruit_config[4]> [(uint32_t *)&config][2].num_lemons = 0;
goto <bb 11>; [100.00%]
<bb 9> [local count: 23622320]:
<L3>:
MEM <struct fruit_config[4]> [(uint32_t *)&config][3].num_lemons = 0;
goto <bb 11>; [100.00%]
<bb 10> [local count: 23622320]:
<L4>:
MEM <struct fruit_config[4]> [(uint32_t *)&config][id_3(D)].num_lemons = 0;
<<< -Warray-bounds
<bb 11> [local count: 118111602]:
# error_14 = PHI <0(7), 255(10), 0(6), 0(9), 0(8)>
config[id_3(D)].num_lemons = 0;
config[id_3(D)].lemons = 0B;
foo (0);
return;
}
In GCC 9 both the function and the final assembly are much more compact:
et_default_config.part.0 (const uint32_t id)
{
struct fruit_config[4] * _2;
sizetype _13;
sizetype _14;
<bb 2> [local count: 118111601]:
_13 = (sizetype) id_3(D);
_14 = _13 * 16;
_2 = &config + _14;
MEM[(unsigned int *)_2] = 0;
config[id_3(D)].lemons = 0B;
foo (0); [tail call]
return;
}
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56456
[Bug 56456] [meta-bug] bogus/missing -Warray-bounds
