https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34653
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|target |rtl-optimization
--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
For the original testcase here is what other compilers do:
LLVM trunk:
movzbl (%rdi), %eax
shrq %rax
andl $120, %eax
movq table(%rax), %rax
retq
ICC 2021.3.0:
movzbl (%rdi), %eax #5.29
shrq $4, %rax #6.23
movq table(,%rax,8), %rax #6.10
ret
MSVC:
movzx eax, BYTE PTR [rcx]
lea rcx, OFFSET FLAT:unsigned long * table ; table
shr rax, 4
mov eax, DWORD PTR [rcx+rax*4]
ret 0
GCC trunk:
movzbl (%rdi), %eax
shrq $4, %rax
movq table(,%rax,8), %rax
Trying 7 -> 8:
7: r89:DI=zero_extend([r92:DI])
REG_DEAD r92:DI
8: {r90:DI=r89:DI 0>>0x4;clobber flags:CC;}
REG_DEAD r89:DI
REG_UNUSED flags:CC
Failed to match this instruction:
(parallel [
(set (reg:DI 90)
(zero_extract:DI (mem:QI (reg:DI 92) [0 *p_4(D)+0 S1 A8])
(const_int 4 [0x4])
(const_int 4 [0x4])))
(clobber (reg:CC 17 flags))
])
Failed to match this instruction:
(set (reg:DI 90)
(zero_extract:DI (mem:QI (reg:DI 92) [0 *p_4(D)+0 S1 A8])
(const_int 4 [0x4])
(const_int 4 [0x4])))
Failed to match this instruction:
(set (reg:DI 90)
(and:DI (subreg:DI (lshiftrt:QI (mem:QI (reg:DI 92) [0 *p_4(D)+0 S1 A8])
(const_int 4 [0x4])) 0)
(const_int 15 [0xf])))
