[llvm] [RISCV] Fold vmv.s.x into load from stack (PR #109774)

[Craig Topper via llvm-commits]

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@@ -0,0 +1,162 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=riscv32 -mattr=+v -verify-machineinstrs | FileCheck --check-prefixes=CHECK,RV32 %s
+; RUN: llc < %s -mtriple=riscv64 -mattr=+v -verify-machineinstrs | FileCheck --check-prefixes=CHECK,RV64 %s
+
+define i64 @i64(<vscale x 1 x i64> %v, i1 %c) {
+; RV32-LABEL: i64:
+; RV32:       # %bb.0:
+; RV32-NEXT:    addi sp, sp, -16
+; RV32-NEXT:    .cfi_def_cfa_offset 16
+; RV32-NEXT:    csrr a1, vlenb
+; RV32-NEXT:    slli a1, a1, 1
+; RV32-NEXT:    sub sp, sp, a1
+; RV32-NEXT:    .cfi_escape 0x0f, 0x0d, 0x72, 0x00, 0x11, 0x10, 0x22, 0x11, 0x02, 0x92, 0xa2, 0x38, 0x00, 0x1e, 0x22 # sp + 16 + 2 * vlenb
+; RV32-NEXT:    addi a1, sp, 16
+; RV32-NEXT:    vs1r.v v8, (a1) # Unknown-size Folded Spill
+; RV32-NEXT:    andi a0, a0, 1
+; RV32-NEXT:    #APP
+; RV32-NEXT:    #NO_APP
+; RV32-NEXT:    beqz a0, .LBB0_2
+; RV32-NEXT:  # %bb.1: # %truebb
+; RV32-NEXT:    li a0, 32
+; RV32-NEXT:    vl1r.v v9, (a1) # Unknown-size Folded Reload
+; RV32-NEXT:    vsetivli zero, 1, e64, m1, ta, ma
+; RV32-NEXT:    vsrl.vx v8, v9, a0
+; RV32-NEXT:    vmv.x.s a1, v8
+; RV32-NEXT:    vmv.x.s a0, v9
+; RV32-NEXT:    j .LBB0_3
+; RV32-NEXT:  .LBB0_2: # %falsebb
+; RV32-NEXT:    li a1, 0
+; RV32-NEXT:  .LBB0_3: # %falsebb
+; RV32-NEXT:    csrr a2, vlenb
+; RV32-NEXT:    slli a2, a2, 1
+; RV32-NEXT:    add sp, sp, a2
+; RV32-NEXT:    addi sp, sp, 16
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: i64:
+; RV64:       # %bb.0:
+; RV64-NEXT:    addi sp, sp, -16
+; RV64-NEXT:    .cfi_def_cfa_offset 16
+; RV64-NEXT:    csrr a1, vlenb
+; RV64-NEXT:    slli a1, a1, 1
+; RV64-NEXT:    sub sp, sp, a1
+; RV64-NEXT:    .cfi_escape 0x0f, 0x0d, 0x72, 0x00, 0x11, 0x10, 0x22, 0x11, 0x02, 0x92, 0xa2, 0x38, 0x00, 0x1e, 0x22 # sp + 16 + 2 * vlenb
+; RV64-NEXT:    addi a1, sp, 16
+; RV64-NEXT:    vs1r.v v8, (a1) # Unknown-size Folded Spill
+; RV64-NEXT:    andi a0, a0, 1
+; RV64-NEXT:    #APP
+; RV64-NEXT:    #NO_APP
+; RV64-NEXT:    beqz a0, .LBB0_2
+; RV64-NEXT:  # %bb.1: # %truebb
+; RV64-NEXT:    ld a0, 16(sp) # 8-byte Folded Reload
+; RV64-NEXT:  .LBB0_2: # %falsebb
+; RV64-NEXT:    csrr a1, vlenb
+; RV64-NEXT:    slli a1, a1, 1
+; RV64-NEXT:    add sp, sp, a1
+; RV64-NEXT:    addi sp, sp, 16
+; RV64-NEXT:    ret
+  tail call void asm sideeffect "", "~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9},~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19},~{v20},~{v21},~{v22},~{v23},~{v24},~{v25},~{v26},~{v27},~{v28},~{v29},~{v30},~{v31}"()
+  br i1 %c, label %truebb, label %falsebb
+truebb:
+  %x = extractelement <vscale x 1 x i64> %v, i32 0
+  ret i64 %x
+falsebb:
+  ret i64 0
+}
+
+define i32 @i32(<vscale x 2 x i32> %v, i1 %c) {
+; CHECK-LABEL: i32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi sp, sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    csrr a1, vlenb
+; CHECK-NEXT:    slli a1, a1, 1
+; CHECK-NEXT:    sub sp, sp, a1
+; CHECK-NEXT:    .cfi_escape 0x0f, 0x0d, 0x72, 0x00, 0x11, 0x10, 0x22, 0x11, 0x02, 0x92, 0xa2, 0x38, 0x00, 0x1e, 0x22 # sp + 16 + 2 * vlenb
+; CHECK-NEXT:    addi a1, sp, 16
+; CHECK-NEXT:    vs1r.v v8, (a1) # Unknown-size Folded Spill
+; CHECK-NEXT:    andi a0, a0, 1
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    beqz a0, .LBB1_2
+; CHECK-NEXT:  # %bb.1: # %truebb
+; CHECK-NEXT:    lw a0, 16(sp) # 8-byte Folded Reload
+; CHECK-NEXT:  .LBB1_2: # %falsebb
+; CHECK-NEXT:    csrr a1, vlenb
+; CHECK-NEXT:    slli a1, a1, 1
+; CHECK-NEXT:    add sp, sp, a1
+; CHECK-NEXT:    addi sp, sp, 16
+; CHECK-NEXT:    ret
+  tail call void asm sideeffect "", "~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9},~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19},~{v20},~{v21},~{v22},~{v23},~{v24},~{v25},~{v26},~{v27},~{v28},~{v29},~{v30},~{v31}"()
+  br i1 %c, label %truebb, label %falsebb
+truebb:
+  %x = extractelement <vscale x 2 x i32> %v, i32 0
+  ret i32 %x
+falsebb:
+  ret i32 0
+}
+
+define i16 @i16(<vscale x 4 x i16> %v, i1 %c) {
+; CHECK-LABEL: i16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi sp, sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    csrr a1, vlenb
----------------
topperc wrote:

> We could have rescheduled the extractelement to avoid the need to spill entirely.

The "scheduler" is per basic block. So it would need to be something else that is capable of hoisting.

https://github.com/llvm/llvm-project/pull/109774