llvm/test/CodeGen/AArch64/implicit-null-check.ll

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -verify-machineinstrs -O3 -mtriple=aarch64-unknown-unknown -enable-implicit-null-checks | FileCheck %s

; Basic test for implicit null check conversion - this is analogous to the
; file with the same name in the X86 tree, but adjusted to remove patterns
; related to memory folding of arithmetic (since aarch64 doesn't), and add
; a couple of aarch64 specific tests.

define i32 @imp_null_check_load_fallthrough(ptr %x) {
; CHECK-LABEL: imp_null_check_load_fallthrough:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp0:
; CHECK-NEXT:    ldr w0, [x0] // on-fault: .LBB0_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB0_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 not_null:
  %t = load i32, ptr %x
  ret i32 %t

is_null:
  ret i32 42
}


define i32 @imp_null_check_load_reorder(ptr %x) {
; CHECK-LABEL: imp_null_check_load_reorder:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp1:
; CHECK-NEXT:    ldr w0, [x0] // on-fault: .LBB1_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB1_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %t = load i32, ptr %x
  ret i32 %t
}

define i32 @imp_null_check_unordered_load(ptr %x) {
; CHECK-LABEL: imp_null_check_unordered_load:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp2:
; CHECK-NEXT:    ldr w0, [x0] // on-fault: .LBB2_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB2_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %t = load atomic i32, ptr %x unordered, align 4
  ret i32 %t
}


; TODO: Can be converted into implicit check.
;; Probably could be implicit, but we're conservative for now
define i32 @imp_null_check_seq_cst_load(ptr %x) {
; CHECK-LABEL: imp_null_check_seq_cst_load:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB3_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ldar w0, [x0]
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB3_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %t = load atomic i32, ptr %x seq_cst, align 4
  ret i32 %t
}

;; Might be memory mapped IO, so can't rely on fault behavior
define i32 @imp_null_check_volatile_load(ptr %x) {
; CHECK-LABEL: imp_null_check_volatile_load:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB4_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ldr w0, [x0]
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB4_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %t = load volatile i32, ptr %x, align 4
  ret i32 %t
}


define i8 @imp_null_check_load_i8(ptr %x) {
; CHECK-LABEL: imp_null_check_load_i8:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp3:
; CHECK-NEXT:    ldrb w0, [x0] // on-fault: .LBB5_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB5_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i8 42

 not_null:
  %t = load i8, ptr %x
  ret i8 %t
}

define i256 @imp_null_check_load_i256(ptr %x) {
; CHECK-LABEL: imp_null_check_load_i256:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB6_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ldp x2, x3, [x0, #16]
; CHECK-NEXT:    ldp x0, x1, [x0]
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB6_2:
; CHECK-NEXT:    mov x1, xzr
; CHECK-NEXT:    mov x2, xzr
; CHECK-NEXT:    mov x3, xzr
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i256 42

 not_null:
  %t = load i256, ptr %x
  ret i256 %t
}



define i32 @imp_null_check_gep_load(ptr %x) {
; CHECK-LABEL: imp_null_check_gep_load:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp4:
; CHECK-NEXT:    ldr w0, [x0, #128] // on-fault: .LBB7_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB7_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %x.gep = getelementptr i32, ptr %x, i32 32
  %t = load i32, ptr %x.gep
  ret i32 %t
}

define i32 @imp_null_check_add_result(ptr %x, i32 %p) {
; CHECK-LABEL: imp_null_check_add_result:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp5:
; CHECK-NEXT:    ldr w8, [x0] // on-fault: .LBB8_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    add w0, w8, w1
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB8_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %t = load i32, ptr %x
  %p1 = add i32 %t, %p
  ret i32 %p1
}

; Can hoist over a potential faulting instruction as long as we don't
; change the conditions under which the instruction faults.
define i32 @imp_null_check_hoist_over_udiv(ptr %x, i32 %a, i32 %b) {
; CHECK-LABEL: imp_null_check_hoist_over_udiv:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB9_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    udiv w8, w1, w2
; CHECK-NEXT:    ldr w9, [x0]
; CHECK-NEXT:    add w0, w9, w8
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB9_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %p1 = udiv i32 %a, %b
  %t = load i32, ptr %x
  %res = add i32 %t, %p1
  ret i32 %res
}


; TODO: We should be able to hoist this - we can on x86, why isn't this
; working for aarch64?  Aliasing?
define i32 @imp_null_check_hoist_over_unrelated_load(ptr %x, ptr %y, ptr %z) {
; CHECK-LABEL: imp_null_check_hoist_over_unrelated_load:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB10_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ldr w8, [x1]
; CHECK-NEXT:    ldr w0, [x0]
; CHECK-NEXT:    str w8, [x2]
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB10_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %t0 = load i32, ptr %y
  %t1 = load i32, ptr %x
  store i32 %t0, ptr %z
  ret i32 %t1
}

define i32 @imp_null_check_gep_load_with_use_dep(ptr %x, i32 %a) {
; CHECK-LABEL: imp_null_check_gep_load_with_use_dep:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp6:
; CHECK-NEXT:    ldr w8, [x0] // on-fault: .LBB11_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    add w9, w0, w1
; CHECK-NEXT:    add w8, w9, w8
; CHECK-NEXT:    add w0, w8, #4
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB11_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %x.loc = getelementptr i32, ptr %x, i32 1
  %y = ptrtoint ptr %x.loc to i32
  %b = add i32 %a, %y
  %t = load i32, ptr %x
  %z = add i32 %t, %b
  ret i32 %z
}

;; TODO: We could handle this case as we can lift the fence into the
;; previous block before the conditional without changing behavior.
define i32 @imp_null_check_load_fence1(ptr %x) {
; CHECK-LABEL: imp_null_check_load_fence1:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB12_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    dmb ishld
; CHECK-NEXT:    ldr w0, [x0]
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB12_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

is_null:
  ret i32 42

not_null:
  fence acquire
  %t = load i32, ptr %x
  ret i32 %t
}

;; TODO: We could handle this case as we can lift the fence into the
;; previous block before the conditional without changing behavior.
define i32 @imp_null_check_load_fence2(ptr %x) {
; CHECK-LABEL: imp_null_check_load_fence2:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB13_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    dmb ish
; CHECK-NEXT:    ldr w0, [x0]
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB13_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

is_null:
  ret i32 42

not_null:
  fence seq_cst
  %t = load i32, ptr %x
  ret i32 %t
}

; TODO: We can fold to implicit null here, not sure why this isn't working
define void @imp_null_check_store(ptr %x) {
; CHECK-LABEL: imp_null_check_store:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB14_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    mov w8, #1
; CHECK-NEXT:    str w8, [x0]
; CHECK-NEXT:  .LBB14_2: // %common.ret
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret void

 not_null:
  store i32 1, ptr %x
  ret void
}

;; TODO: can be implicit
define void @imp_null_check_unordered_store(ptr %x) {
; CHECK-LABEL: imp_null_check_unordered_store:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:    cbz x0, .LBB15_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    mov w8, #1
; CHECK-NEXT:    str w8, [x0]
; CHECK-NEXT:  .LBB15_2: // %common.ret
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret void

 not_null:
  store atomic i32 1, ptr %x unordered, align 4
  ret void
}

define i32 @imp_null_check_neg_gep_load(ptr %x) {
; CHECK-LABEL: imp_null_check_neg_gep_load:
; CHECK:       // %bb.0: // %entry
; CHECK-NEXT:  .Ltmp7:
; CHECK-NEXT:    ldur w0, [x0, #-128] // on-fault: .LBB16_2
; CHECK-NEXT:  // %bb.1: // %not_null
; CHECK-NEXT:    ret
; CHECK-NEXT:  .LBB16_2:
; CHECK-NEXT:    mov w0, #42
; CHECK-NEXT:    ret
 entry:
  %c = icmp eq ptr %x, null
  br i1 %c, label %is_null, label %not_null, !make.implicit !0

 is_null:
  ret i32 42

 not_null:
  %x.gep = getelementptr i32, ptr %x, i32 -32
  %t = load i32, ptr %x.gep
  ret i32 %t
}

!0 = !{}