https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43147
H.J. Lu <hjl.tools at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|hjl.tools at gmail dot com |unassigned at gcc dot
gnu.org
Component|target |rtl-optimization
Version|4.4.1 |12.0
--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> ---
From
https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577991.html
Trying 5 -> 7:
5: r85:V4SF=[`*.LC0']
REG_EQUAL const_vector
7: r84:V4SF=vec_select(vec_concat(r85:V4SF,r85:V4SF),parallel)
REG_DEAD r85:V4SF
REG_EQUAL const_vector
Failed to match this instruction:
(set (reg:V4SF 84)
(const_vector:V4SF [
(const_double:SF 3.0e+0 [0x0.cp+2])
(const_double:SF 2.0e+0 [0x0.8p+2])
(const_double:SF 4.0e+0 [0x0.8p+3])
(const_double:SF 1.0e+0 [0x0.8p+1])
]))
(insn 5 2 7 2 (set (reg:V4SF 85)
(mem/u/c:V4SF (symbol_ref/u:DI ("*.LC0") [flags 0x2]) [0 S16
A128]))
"/export/users/liuhongt/install/git_trunk_master_native/lib/gcc/x86_64-pc-linux-gnu/12.0.0/include/xmmintrin.h":746:19
1600 {movv4sf_internal}
(expr_list:REG_EQUAL (const_vector:V4SF [
(const_double:SF 4.0e+0 [0x0.8p+3])
(const_double:SF 3.0e+0 [0x0.cp+2])
(const_double:SF 2.0e+0 [0x0.8p+2])
(const_double:SF 1.0e+0 [0x0.8p+1])
])
(nil)))
(insn 7 5 11 2 (set (reg:V4SF 84)
(vec_select:V4SF (vec_concat:V8SF (reg:V4SF 85)
(reg:V4SF 85))
(parallel [
(const_int 1 [0x1])
(const_int 2 [0x2])
(const_int 4 [0x4])
(const_int 7 [0x7])
])))
"/export/users/liuhongt/install/git_trunk_master_native/lib/gcc/x86_64-pc-linux-gnu/12.0.0/include/xmmintrin.h":746:19
3015 {sse_shufps_v4sf}
(expr_list:REG_DEAD (reg:V4SF 85)
(expr_list:REG_EQUAL (const_vector:V4SF [
(const_double:SF 3.0e+0 [0x0.cp+2])
(const_double:SF 2.0e+0 [0x0.8p+2])
(const_double:SF 4.0e+0 [0x0.8p+3])
(const_double:SF 1.0e+0 [0x0.8p+1])
])
(nil))))
I think pass_combine should be extended to force illegitimate constant
to constant pool and recog load insn again, It looks like a general
optimization that better not do it in the backend.
