https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121306
Bug ID: 121306
Summary: [16 Regression] testcase failures after
r16-2614-g965564eafb721f on x86_64
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Target: x86_64
gcc.target/i386/pr78904-1b.c started to fail after this change (this is not
fixed by the fix for the wrong code issue; PR 121302).
with this change we have:
```
Trying 9 -> 10:
9:
{r107:QI=zero_extract(r110:DI,0x8,0x8)#0&zero_extract(r103:DI,0x8,0x8)#0;clobber
flags:CC;}
REG_UNUSED flags:CC
REG_DEAD r110:DI
10: zero_extract(r103:DI,0x8,0x8)=r107:QI#0
REG_DEAD r107:QI
Failed to match this instruction:
(set (zero_extract:DI (reg/v:DI 103 [ a ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
(lshiftrt:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8])))
Failed to match this instruction:
(set (reg/v:DI 103 [ a ])
(ior:DI (and:DI (reg/v:DI 103 [ a ])
(const_int -65281 [0xffffffffffff00ff]))
(and:DI (ashift:DI (lshiftrt:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8]))
(const_int 8 [0x8]))
(const_int 65280 [0xff00]))))
```
But without we get:
```
Trying 9 -> 10:
9:
{r107:QI=zero_extract(r110:DI,0x8,0x8)#0&zero_extract(r103:DI,0x8,0x8)#0;clobber
flags:CC;}
REG_UNUSED flags:CC
REG_DEAD r110:DI
10: zero_extract(r103:DI,0x8,0x8)=r107:QI#0
REG_DEAD r107:QI
Successfully matched this instruction:
(set (zero_extract:DI (reg/v:DI 103 [ a ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
(zero_extract:DI (and:DI (reg:DI 110 [ b ])
(reg/v:DI 103 [ a ]))
(const_int 8 [0x8])
(const_int 8 [0x8])))
```
I think this is because we lost the `&0xff` which was required to recognize the
zero_extract.
