llvm/test/CodeGen/ARM/musttail.ll

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc -mtriple=armv7a-none-eabi %s -o - | FileCheck %s

declare i32 @many_args_callee(i32 %0, i32 %1, i32 %2, i32 %3, i32 %4, i32 %5)

define i32 @many_args_tail(i32 %0, i32 %1, i32 %2, i32 %3, i32  %4, i32  %5) {
; CHECK-LABEL: many_args_tail:
; CHECK:       @ %bb.0:
; CHECK-NEXT:    mov r0, #5
; CHECK-NEXT:    mov r1, #2
; CHECK-NEXT:    str r0, [sp]
; CHECK-NEXT:    mov r0, #6
; CHECK-NEXT:    str r0, [sp, #4]
; CHECK-NEXT:    mov r0, #1
; CHECK-NEXT:    mov r2, #3
; CHECK-NEXT:    mov r3, #4
; CHECK-NEXT:    b many_args_callee
  %ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
  ret i32 %ret
}

define i32 @many_args_musttail(i32 %0, i32 %1, i32 %2, i32 %3, i32  %4, i32  %5) {
; CHECK-LABEL: many_args_musttail:
; CHECK:       @ %bb.0:
; CHECK-NEXT:    mov r0, #5
; CHECK-NEXT:    mov r1, #2
; CHECK-NEXT:    str r0, [sp]
; CHECK-NEXT:    mov r0, #6
; CHECK-NEXT:    str r0, [sp, #4]
; CHECK-NEXT:    mov r0, #1
; CHECK-NEXT:    mov r2, #3
; CHECK-NEXT:    mov r3, #4
; CHECK-NEXT:    b many_args_callee
  %ret = musttail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
  ret i32 %ret
}

; This function has more arguments than it's tail-callee. This isn't valid for
; the musttail attribute, but can still be tail-called as a non-guaranteed
; optimisation, because the outgoing arguments to @many_args_callee fit in the
; stack space allocated by the caller of @more_args_tail.
define i32 @more_args_tail(i32 %0, i32 %1, i32 %2, i32 %3, i32  %4, i32 %5, i32 %6) {
; CHECK-LABEL: more_args_tail:
; CHECK:       @ %bb.0:
; CHECK-NEXT:    mov r0, #5
; CHECK-NEXT:    mov r1, #2
; CHECK-NEXT:    str r0, [sp]
; CHECK-NEXT:    mov r0, #6
; CHECK-NEXT:    str r0, [sp, #4]
; CHECK-NEXT:    mov r0, #1
; CHECK-NEXT:    mov r2, #3
; CHECK-NEXT:    mov r3, #4
; CHECK-NEXT:    b many_args_callee
  %ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
  ret i32 %ret
}

; Again, this isn't valid for musttail, but can be tail-called in practice
; because the stack size if the same.
define i32 @different_args_tail(i64 %0, i64 %1, i64 %2) {
; CHECK-LABEL: different_args_tail:
; CHECK:       @ %bb.0:
; CHECK-NEXT:    mov r0, #5
; CHECK-NEXT:    mov r1, #2
; CHECK-NEXT:    str r0, [sp]
; CHECK-NEXT:    mov r0, #6
; CHECK-NEXT:    str r0, [sp, #4]
; CHECK-NEXT:    mov r0, #1
; CHECK-NEXT:    mov r2, #3
; CHECK-NEXT:    mov r3, #4
; CHECK-NEXT:    b many_args_callee
  %ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
  ret i32 %ret
}

; Here, the caller requires less stack space for it's arguments than the
; callee, so it would not ba valid to do a tail-call.
define i32 @fewer_args_tail(i32 %0, i32 %1, i32 %2, i32 %3, i32  %4) {
; CHECK-LABEL: fewer_args_tail:
; CHECK:       @ %bb.0:
; CHECK-NEXT:    .save {r11, lr}
; CHECK-NEXT:    push {r11, lr}
; CHECK-NEXT:    .pad #8
; CHECK-NEXT:    sub sp, sp, #8
; CHECK-NEXT:    mov r1, #6
; CHECK-NEXT:    mov r0, #5
; CHECK-NEXT:    strd r0, r1, [sp]
; CHECK-NEXT:    mov r0, #1
; CHECK-NEXT:    mov r1, #2
; CHECK-NEXT:    mov r2, #3
; CHECK-NEXT:    mov r3, #4
; CHECK-NEXT:    bl many_args_callee
; CHECK-NEXT:    add sp, sp, #8
; CHECK-NEXT:    pop {r11, pc}
  %ret = tail call i32 @many_args_callee(i32 1, i32 2, i32 3, i32 4, i32 5, i32 6)
  ret i32 %ret
}

declare void @sret_callee(ptr sret({ double, double }) align 8)

; Functions which return by sret can be tail-called because the incoming sret
; pointer gets passed through to the callee.
define void @sret_caller_tail(ptr sret({ double, double }) align 8 %result) {
; CHECK-LABEL: sret_caller_tail:
; CHECK:       @ %bb.0: @ %entry
; CHECK-NEXT:    b sret_callee
entry:
  tail call void @sret_callee(ptr sret({ double, double }) align 8 %result)
  ret void
}

define void @sret_caller_musttail(ptr sret({ double, double }) align 8 %result) {
; CHECK-LABEL: sret_caller_musttail:
; CHECK:       @ %bb.0: @ %entry
; CHECK-NEXT:    b sret_callee
entry:
  musttail call void @sret_callee(ptr sret({ double, double }) align 8 %result)
  ret void
}