https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93930
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The cost changes affect the RTL LIM.-Set in insn 22 is invariant (0), cost 32, depends on -Set in insn 27 is invariant (1), cost 32, depends on -Set in insn 32 is invariant (2), cost 32, depends on -Set in insn 37 is invariant (3), cost 32, depends on -Set in insn 61 is invariant (4), cost 32, depends on -Set in insn 66 is invariant (5), cost 32, depends on -Set in insn 71 is invariant (6), cost 32, depends on -Set in insn 76 is invariant (7), cost 32, depends on -Set in insn 101 is invariant (8), cost 32, depends on -Set in insn 106 is invariant (9), cost 32, depends on -Set in insn 111 is invariant (10), cost 32, depends on -Set in insn 116 is invariant (11), cost 32, depends on -Decided to move invariant 0 -- gain 32 -Decided to move invariant 1 -- gain 32 -Decided to move invariant 2 -- gain 32 -Decided to move invariant 3 -- gain 32 -Decided to move invariant 4 -- gain 32 -Decided to move invariant 5 -- gain 32 -Decided to move invariant 6 -- gain 32 -Decided to move invariant 7 -- gain 32 -Decided to move invariant 8 -- gain 32 -Decided to move invariant 9 -- gain 32 -Decided to move invariant 10 -- gain 10 -Decided to move invariant 11 -- gain 30 +Set in insn 22 is invariant (0), cost 4, depends on +Set in insn 27 is invariant (1), cost 4, depends on +Set in insn 32 is invariant (2), cost 4, depends on +Set in insn 37 is invariant (3), cost 4, depends on +Set in insn 61 is invariant (4), cost 4, depends on +Set in insn 66 is invariant (5), cost 4, depends on +Set in insn 71 is invariant (6), cost 4, depends on +Set in insn 76 is invariant (7), cost 4, depends on +Set in insn 101 is invariant (8), cost 4, depends on +Set in insn 106 is invariant (9), cost 4, depends on +Set in insn 111 is invariant (10), cost 4, depends on +Set in insn 116 is invariant (11), cost 4, depends on +Decided to move invariant 0 -- gain 4 +Decided to move invariant 1 -- gain 4 +Decided to move invariant 2 -- gain 4 +Decided to move invariant 3 -- gain 4 +Decided to move invariant 4 -- gain 4 +Decided to move invariant 5 -- gain 4 +Decided to move invariant 6 -- gain 4 +Decided to move invariant 7 -- gain 4 +Decided to move invariant 8 -- gain 4 +Decided to move invariant 9 -- gain 4 which means invariant 10 and 11 aren't moved anymore. Those two are: -(insn 111 106 116 3 (set (reg:V16SF 210) - (vec_duplicate:V16SF (vec_select:SF (reg:V4SF 234) - (parallel [ - (const_int 0 [0]) - ])))) "include/avx512fintrin.h":207 4206 {avx512f_vec_dupv16sf} - (expr_list:REG_EQUAL (const_vector:V16SF [ - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - (const_double:SF 2.3e+1 [0x0.b8p+5]) - ]) - (nil))) -(insn 116 111 139 3 (set (reg:V16SF 214) - (vec_duplicate:V16SF (vec_select:SF (reg:V4SF 235) - (parallel [ - (const_int 0 [0]) - ])))) "include/avx512fintrin.h":207 4206 {avx512f_vec_dupv16sf} - (expr_list:REG_EQUAL (const_vector:V16SF [ - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - (const_double:SF 2.4e+1 [0x0.cp+5]) - ]) - (nil))) and I bet the reason they are using the const costs are the REG_EQUAL notes. The setters of their sources are: (insn 169 168 170 3 (set (reg:V4SF 234) (mem/u/c:V4SF (symbol_ref/u:DI ("*.LC10") [flags 0x2]) [2 S16 A128])) -1 (expr_list:REG_EQUAL (const_vector:V4SF [ (const_double:SF 2.3e+1 [0x0.b8p+5]) (const_double:SF 0.0 [0x0.0p+0]) (const_double:SF 0.0 [0x0.0p+0]) (const_double:SF 0.0 [0x0.0p+0]) ]) (nil))) (insn 170 169 22 3 (set (reg:V4SF 235) (mem/u/c:V4SF (symbol_ref/u:DI ("*.LC11") [flags 0x2]) [2 S16 A128])) -1 (expr_list:REG_EQUAL (const_vector:V4SF [ (const_double:SF 2.4e+1 [0x0.cp+5]) (const_double:SF 0.0 [0x0.0p+0]) (const_double:SF 0.0 [0x0.0p+0]) (const_double:SF 0.0 [0x0.0p+0]) ]) (nil)))