llvm/test/CodeGen/RISCV/vlenb.ll

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -O3 < %s -mtriple=riscv32 | FileCheck %s

; These tests demonstrate optimizations involving copies from VLENB.

define void @unused_copy_is_dead() {
; CHECK-LABEL: unused_copy_is_dead:
; CHECK:       # %bb.0: # %entry
; CHECK-NEXT:    ret
entry:
  call i32 @llvm.read_register.i32(metadata !0)
  ret void
}

define i32 @simple_cse() {
; CHECK-LABEL: simple_cse:
; CHECK:       # %bb.0: # %entry
; CHECK-NEXT:    csrr a0, vlenb
; CHECK-NEXT:    sub a0, a0, a0
; CHECK-NEXT:    ret
entry:
  %v1 = call i32 @llvm.read_register.i32(metadata !0)
  %v2 = call i32 @llvm.read_register.i32(metadata !0)
  %sub = sub i32 %v1, %v2
  ret i32 %sub
}

define i32 @sink_to_use_branch(i1 %c) {
; CHECK-LABEL: sink_to_use_branch:
; CHECK:       # %bb.0: # %entry
; CHECK-NEXT:    andi a0, a0, 1
; CHECK-NEXT:    beqz a0, .LBB2_2
; CHECK-NEXT:  # %bb.1: # %used
; CHECK-NEXT:    csrr a0, vlenb
; CHECK-NEXT:  .LBB2_2: # %unused
; CHECK-NEXT:    ret
entry:
  %v1 = call i32 @llvm.read_register.i32(metadata !0)
  br i1 %c, label %used, label %unused
used:
  ret i32 %v1
unused:
  ret i32 0
}

define i32 @sink_to_use_call() {
; CHECK-LABEL: sink_to_use_call:
; CHECK:       # %bb.0: # %entry
; CHECK-NEXT:    addi sp, sp, -16
; CHECK-NEXT:    .cfi_def_cfa_offset 16
; CHECK-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
; CHECK-NEXT:    sw s0, 8(sp) # 4-byte Folded Spill
; CHECK-NEXT:    .cfi_offset ra, -4
; CHECK-NEXT:    .cfi_offset s0, -8
; CHECK-NEXT:    csrr s0, vlenb
; CHECK-NEXT:    call unknown
; CHECK-NEXT:    mv a0, s0
; CHECK-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
; CHECK-NEXT:    lw s0, 8(sp) # 4-byte Folded Reload
; CHECK-NEXT:    .cfi_restore ra
; CHECK-NEXT:    .cfi_restore s0
; CHECK-NEXT:    addi sp, sp, 16
; CHECK-NEXT:    .cfi_def_cfa_offset 0
; CHECK-NEXT:    ret
entry:
  %v1 = call i32 @llvm.read_register.i32(metadata !0)
  call void @unknown() ; maythrow
  ret i32 %v1
}

define void @machine_licm() {
; CHECK-LABEL: machine_licm:
; CHECK:       # %bb.0: # %entry
; CHECK-NEXT:    addi sp, sp, -16
; CHECK-NEXT:    .cfi_def_cfa_offset 16
; CHECK-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
; CHECK-NEXT:    sw s0, 8(sp) # 4-byte Folded Spill
; CHECK-NEXT:    .cfi_offset ra, -4
; CHECK-NEXT:    .cfi_offset s0, -8
; CHECK-NEXT:    csrr s0, vlenb
; CHECK-NEXT:  .LBB4_1: # %loop
; CHECK-NEXT:    # =>This Inner Loop Header: Depth=1
; CHECK-NEXT:    mv a0, s0
; CHECK-NEXT:    call use
; CHECK-NEXT:    j .LBB4_1
entry:
  br label %loop

loop:
  %v1 = call i32 @llvm.read_register.i32(metadata !0)
  call void @use(i32 %v1)
  br label %loop
}

declare void @unknown()
declare void @use(i32)

!0 = !{!"vlenb"}