https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110052
--- Comment #3 from Bernhard Reutner-Fischer <aldot at gcc dot gnu.org> ---
Note that in this particular case myrealloc() is static, maybe i should have
omitted the noipa attribute for it was only meant to simplify analysis and
there is no such attribute in the original code.
Furthermore, i would have hoped that given the placement of the definition of
myrealloc() before the typedef foo_t, it should be unlikely that the usage of
*foo would invalidate such an optimisation _in this particular case_. While the
original code unfortunately does not mark *foo as restrict, adding restrict
would hopefully make it clear that myrealloc() has no business in comparing
foo's struct members, i'd hope?
When i drop the noipa attribute in the v1 testcase to make it similar to the
motivating case, i get:
9: 0000000000000000 44 FUNC GLOBAL DEFAULT 4 bloat
12: 0000000000000000 38 FUNC GLOBAL DEFAULT 6 ok
0000000000000000 <bloat>:
0: 53 push %rbx
1: 48 83 7f 08 00 cmpq $0x0,0x8(%rdi)
6: 48 89 fb mov %rdi,%rbx
9: 8b 47 14 mov 0x14(%rdi),%eax
c: 75 19 jne 27 <bloat+0x27>
e: bf d0 01 00 00 mov $0x1d0,%edi
13: e8 00 00 00 00 callq 18 <bloat+0x18>
18: 48 85 c0 test %rax,%rax
1b: 75 05 jne 22 <bloat+0x22>
1d: e8 00 00 00 00 callq 22 <bloat+0x22>
22: b8 d0 01 00 00 mov $0x1d0,%eax
27: 89 43 14 mov %eax,0x14(%rbx)
2a: 5b pop %rbx
2b: c3 retq
Disassembly of section .text.ok:
0000000000000000 <ok>:
0: 48 83 7f 08 00 cmpq $0x0,0x8(%rdi)
5: 75 1e jne 25 <ok+0x25>
7: 52 push %rdx
8: c7 47 14 d0 01 00 00 movl $0x1d0,0x14(%rdi)
f: bf d0 01 00 00 mov $0x1d0,%edi
14: e8 00 00 00 00 callq 19 <ok+0x19>
19: 48 85 c0 test %rax,%rax
1c: 75 05 jne 23 <ok+0x23>
1e: e8 00 00 00 00 callq 23 <ok+0x23>
23: 58 pop %rax
24: c3 retq
25: c3 retq
