[Bug target/98957] [11 Regression] [x86] Odd code generation for 8-bit left shift

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98957

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The first change is during cse1:
 (insn 10 9 11 2 (parallel [
             (set (reg:HI 90)
                 (and:HI (subreg:HI (reg:QI 89) 0)
                     (const_int 1 [0x1])))
             (clobber (reg:CC 17 flags))
         ]) "pr98957.c":3:14 489 {*andhi_1}
      (expr_list:REG_DEAD (reg:QI 89)
         (expr_list:REG_UNUSED (reg:CC 17 flags)
             (nil))))
 (insn 11 10 12 2 (set (reg:QI 86)
         (subreg:QI (reg:HI 90) 0)) "pr98957.c":3:14 77 {*movqi_internal}
      (expr_list:REG_DEAD (reg:HI 90)
         (nil)))
 (insn 12 11 16 2 (set (reg:QI 83 [ <retval> ])
         (subreg:QI (reg:HI 90) 0)) "pr98957.c":3:14 77 {*movqi_internal}
      (expr_list:REG_DEAD (reg:QI 86)
         (nil)))
 (insn 16 12 17 2 (set (reg/i:QI 0 ax)
-        (subreg:QI (reg:HI 90) 0)) "pr98957.c":4:1 77 {*movqi_internal}
+        (reg:QI 86)) "pr98957.c":4:1 77 {*movqi_internal}
      (expr_list:REG_DEAD (reg:QI 83 [ <retval> ])
         (nil)))
and that then changes how combine handles it.