[Bug target/93930] [8/9/10 Regression] Unnecessary broadcast instructions for AVX512

[jakub at gcc dot gnu.org]

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)))