[llvm] [RegAlloc][RISCV] Increase the spill weight by target factor (PR #113675)

[Philip Reames via llvm-commits]

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@@ -2038,231 +2037,145 @@ define <vscale x 16 x i64> @vp_ctpop_nxv16i64(<vscale x 16 x i64> %va, <vscale x
 ; RV32-NEXT:    addi a3, a3, -1
 ; RV32-NEXT:    and a2, a3, a2
 ; RV32-NEXT:    vsetvli zero, a2, e64, m8, ta, ma
-; RV32-NEXT:    vsrl.vi v8, v16, 1, v0.t
-; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    li a4, 48
-; RV32-NEXT:    mul a3, a3, a4
-; RV32-NEXT:    add a3, sp, a3
-; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vs8r.v v8, (a3) # Unknown-size Folded Spill
+; RV32-NEXT:    vsrl.vi v24, v16, 1, v0.t
 ; RV32-NEXT:    lui a3, 349525
 ; RV32-NEXT:    addi a3, a3, 1365
 ; RV32-NEXT:    vsetvli a4, zero, e32, m8, ta, ma
 ; RV32-NEXT:    vmv.v.x v8, a3
 ; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    slli a3, a3, 5
-; RV32-NEXT:    add a3, sp, a3
-; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vs8r.v v8, (a3) # Unknown-size Folded Spill
-; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    slli a3, a3, 5
-; RV32-NEXT:    add a3, sp, a3
-; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vl8r.v v8, (a3) # Unknown-size Folded Reload
-; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    li a4, 48
+; RV32-NEXT:    li a4, 24
 ; RV32-NEXT:    mul a3, a3, a4
 ; RV32-NEXT:    add a3, sp, a3
 ; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vl8r.v v24, (a3) # Unknown-size Folded Reload
+; RV32-NEXT:    vs8r.v v8, (a3) # Unknown-size Folded Spill
 ; RV32-NEXT:    vsetvli zero, a2, e64, m8, ta, ma
-; RV32-NEXT:    vand.vv v8, v24, v8, v0.t
-; RV32-NEXT:    vsub.vv v16, v16, v8, v0.t
+; RV32-NEXT:    vand.vv v24, v24, v8, v0.t
+; RV32-NEXT:    vsub.vv v16, v16, v24, v0.t
 ; RV32-NEXT:    lui a3, 209715
 ; RV32-NEXT:    addi a3, a3, 819
 ; RV32-NEXT:    vsetvli a4, zero, e32, m8, ta, ma
 ; RV32-NEXT:    vmv.v.x v8, a3
-; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    li a4, 48
-; RV32-NEXT:    mul a3, a3, a4
-; RV32-NEXT:    add a3, sp, a3
-; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vs8r.v v8, (a3) # Unknown-size Folded Spill
-; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    li a4, 48
-; RV32-NEXT:    mul a3, a3, a4
-; RV32-NEXT:    add a3, sp, a3
-; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vl8r.v v8, (a3) # Unknown-size Folded Reload
 ; RV32-NEXT:    vsetvli zero, a2, e64, m8, ta, ma
-; RV32-NEXT:    vand.vv v8, v16, v8, v0.t
+; RV32-NEXT:    vand.vv v24, v16, v8, v0.t
 ; RV32-NEXT:    vsrl.vi v16, v16, 2, v0.t
 ; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    li a4, 48
+; RV32-NEXT:    li a4, 40
 ; RV32-NEXT:    mul a3, a3, a4
 ; RV32-NEXT:    add a3, sp, a3
 ; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vl8r.v v24, (a3) # Unknown-size Folded Reload
-; RV32-NEXT:    vand.vv v16, v16, v24, v0.t
-; RV32-NEXT:    vadd.vv v8, v8, v16, v0.t
-; RV32-NEXT:    vsrl.vi v16, v8, 4, v0.t
-; RV32-NEXT:    vadd.vv v8, v8, v16, v0.t
+; RV32-NEXT:    vs8r.v v8, (a3) # Unknown-size Folded Spill
+; RV32-NEXT:    vand.vv v16, v16, v8, v0.t
+; RV32-NEXT:    vadd.vv v16, v24, v16, v0.t
+; RV32-NEXT:    vsrl.vi v24, v16, 4, v0.t
+; RV32-NEXT:    vadd.vv v16, v16, v24, v0.t
 ; RV32-NEXT:    lui a3, 61681
 ; RV32-NEXT:    addi a3, a3, -241
 ; RV32-NEXT:    vsetvli a4, zero, e32, m8, ta, ma
-; RV32-NEXT:    vmv.v.x v16, a3
+; RV32-NEXT:    vmv.v.x v8, a3
 ; RV32-NEXT:    csrr a3, vlenb
-; RV32-NEXT:    li a4, 24
-; RV32-NEXT:    mul a3, a3, a4
+; RV32-NEXT:    slli a3, a3, 4
 ; RV32-NEXT:    add a3, sp, a3
 ; RV32-NEXT:    addi a3, a3, 16
-; RV32-NEXT:    vs8r.v v16, (a3) # Unknown-size Folded Spill
+; RV32-NEXT:    vs8r.v v8, (a3) # Unknown-size Folded Spill
----------------
preames wrote:

This case looks suspicious.  We have existing logic to rematerialize a vmv.v.x instead of spilling it.  Why didn't that kick in here?  Both before and after.

https://github.com/llvm/llvm-project/pull/113675