llvm/test/CodeGen/WebAssembly/reg-stackify.ll

; RUN: llc < %s -asm-verbose=false -verify-machineinstrs | FileCheck %s

; Test the register stackifier pass.

target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"

; No because of pointer aliasing.

; CHECK-LABEL: no0:
; CHECK: return $1{{$}}
define i32 @no0(i32* %p, i32* %q) {
  %t = load i32, i32* %q
  store i32 0, i32* %p
  ret i32 %t
}

; No because of side effects.

; CHECK-LABEL: no1:
; CHECK: return $1{{$}}
define i32 @no1(i32* %p, i32* dereferenceable(4) %q) {
  %t = load volatile i32, i32* %q, !invariant.load !0
  store volatile i32 0, i32* %p
  ret i32 %t
}

; Yes because of invariant load and no side effects.

; CHECK-LABEL: yes0:
; CHECK: return $pop0{{$}}
define i32 @yes0(i32* %p, i32* dereferenceable(4) %q) {
  %t = load i32, i32* %q, !invariant.load !0
  store i32 0, i32* %p
  ret i32 %t
}

; Yes because of no intervening side effects.

; CHECK-LABEL: yes1:
; CHECK: return $pop0{{$}}
define i32 @yes1(i32* %q) {
  %t = load volatile i32, i32* %q
  ret i32 %t
}

; Don't schedule stack uses into the stack. To reduce register pressure, the
; scheduler might be tempted to move the definition of $2 down. However, this
; would risk getting incorrect liveness if the instructions are later
; rearranged to make the stack contiguous.

; CHECK-LABEL: stack_uses:
; CHECK-NEXT: .param i32, i32, i32, i32{{$}}
; CHECK-NEXT: .result i32{{$}}
; CHECK-NEXT: block{{$}}
; CHECK-NEXT: i32.const   $push13=, 1{{$}}
; CHECK-NEXT: i32.lt_s    $push0=, $0, $pop13{{$}}
; CHECK-NEXT: i32.const   $push1=, 2{{$}}
; CHECK-NEXT: i32.lt_s    $push2=, $1, $pop1{{$}}
; CHECK-NEXT: i32.xor     $push5=, $pop0, $pop2{{$}}
; CHECK-NEXT: i32.const   $push12=, 1{{$}}
; CHECK-NEXT: i32.lt_s    $push3=, $2, $pop12{{$}}
; CHECK-NEXT: i32.const   $push11=, 2{{$}}
; CHECK-NEXT: i32.lt_s    $push4=, $3, $pop11{{$}}
; CHECK-NEXT: i32.xor     $push6=, $pop3, $pop4{{$}}
; CHECK-NEXT: i32.xor     $push7=, $pop5, $pop6{{$}}
; CHECK-NEXT: i32.const   $push10=, 1{{$}}
; CHECK-NEXT: i32.ne      $push8=, $pop7, $pop10{{$}}
; CHECK-NEXT: br_if       0, $pop8{{$}}
; CHECK-NEXT: i32.const   $push9=, 0{{$}}
; CHECK-NEXT: return      $pop9{{$}}
; CHECK-NEXT: .LBB4_2:
; CHECK-NEXT: end_block{{$}}
; CHECK-NEXT: i32.const   $push14=, 1{{$}}
; CHECK-NEXT: return      $pop14{{$}}
define i32 @stack_uses(i32 %x, i32 %y, i32 %z, i32 %w) {
entry:
  %c = icmp sle i32 %x, 0
  %d = icmp sle i32 %y, 1
  %e = icmp sle i32 %z, 0
  %f = icmp sle i32 %w, 1
  %g = xor i1 %c, %d
  %h = xor i1 %e, %f
  %i = xor i1 %g, %h
  br i1 %i, label %true, label %false
true:
  ret i32 0
false:
  ret i32 1
}

; Test an interesting case where the load has multiple uses and cannot
; be trivially stackified. However, it can be stackified with a tee_local.

; CHECK-LABEL: multiple_uses:
; CHECK-NEXT: .param       i32, i32, i32{{$}}
; CHECK-NEXT: .local       i32{{$}}
; CHECK-NEXT: block{{$}}
; CHECK-NEXT: i32.load    $push0=, 0($2){{$}}
; CHECK-NEXT: tee_local   $push3=, $3=, $pop0{{$}}
; CHECK-NEXT: i32.ge_u    $push1=, $pop3, $1{{$}}
; CHECK-NEXT: br_if       0, $pop1{{$}}
; CHECK-NEXT: i32.lt_u    $push2=, $3, $0{{$}}
; CHECK-NEXT: br_if       0, $pop2{{$}}
; CHECK-NEXT: i32.store   $discard=, 0($2), $3{{$}}
; CHECK-NEXT: .LBB5_3:
; CHECK-NEXT: end_block{{$}}
; CHECK-NEXT: return{{$}}
define void @multiple_uses(i32* %arg0, i32* %arg1, i32* %arg2) nounwind {
bb:
  br label %loop

loop:
  %tmp7 = load i32, i32* %arg2
  %tmp8 = inttoptr i32 %tmp7 to i32*
  %tmp9 = icmp uge i32* %tmp8, %arg1
  %tmp10 = icmp ult i32* %tmp8, %arg0
  %tmp11 = or i1 %tmp9, %tmp10
  br i1 %tmp11, label %back, label %then

then:
  store i32 %tmp7, i32* %arg2
  br label %back

back:
  br i1 undef, label %return, label %loop

return:
  ret void
}

; Don't stackify stores effects across other instructions with side effects.

; CHECK:      side_effects:
; CHECK:      store
; CHECK-NEXT: call
; CHECK-NEXT: store
; CHECK-NEXT: call
declare void @evoke_side_effects()
define hidden void @stackify_store_across_side_effects(double* nocapture %d) {
entry:
  store double 2.0, double* %d
  call void @evoke_side_effects()
  store double 2.0, double* %d
  call void @evoke_side_effects()
  ret void
}

; Div instructions have side effects and can't be reordered, but this entire
; function should still be able to be stackified because it's already in
; tree order.

; CHECK-LABEL: div_tree:
; CHECK-NEXT: .param i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32{{$}}
; CHECK-NEXT: .result     i32{{$}}
; CHECK-NEXT: i32.div_s   $push0=, $0, $1
; CHECK-NEXT: i32.div_s   $push1=, $2, $3
; CHECK-NEXT: i32.div_s   $push2=, $pop0, $pop1
; CHECK-NEXT: i32.div_s   $push3=, $4, $5
; CHECK-NEXT: i32.div_s   $push4=, $6, $7
; CHECK-NEXT: i32.div_s   $push5=, $pop3, $pop4
; CHECK-NEXT: i32.div_s   $push6=, $pop2, $pop5
; CHECK-NEXT: i32.div_s   $push7=, $8, $9
; CHECK-NEXT: i32.div_s   $push8=, $10, $11
; CHECK-NEXT: i32.div_s   $push9=, $pop7, $pop8
; CHECK-NEXT: i32.div_s   $push10=, $12, $13
; CHECK-NEXT: i32.div_s   $push11=, $14, $15
; CHECK-NEXT: i32.div_s   $push12=, $pop10, $pop11
; CHECK-NEXT: i32.div_s   $push13=, $pop9, $pop12
; CHECK-NEXT: i32.div_s   $push14=, $pop6, $pop13
; CHECK-NEXT: return      $pop14
define i32 @div_tree(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f, i32 %g, i32 %h, i32 %i, i32 %j, i32 %k, i32 %l, i32 %m, i32 %n, i32 %o, i32 %p) {
entry:
  %div = sdiv i32 %a, %b
  %div1 = sdiv i32 %c, %d
  %div2 = sdiv i32 %div, %div1
  %div3 = sdiv i32 %e, %f
  %div4 = sdiv i32 %g, %h
  %div5 = sdiv i32 %div3, %div4
  %div6 = sdiv i32 %div2, %div5
  %div7 = sdiv i32 %i, %j
  %div8 = sdiv i32 %k, %l
  %div9 = sdiv i32 %div7, %div8
  %div10 = sdiv i32 %m, %n
  %div11 = sdiv i32 %o, %p
  %div12 = sdiv i32 %div10, %div11
  %div13 = sdiv i32 %div9, %div12
  %div14 = sdiv i32 %div6, %div13
  ret i32 %div14
}

; A simple multiple-use case.

; CHECK-LABEL: simple_multiple_use:
; CHECK-NEXT:  .param      i32, i32{{$}}
; CHECK-NEXT:  i32.mul     $push0=, $1, $0{{$}}
; CHECK-NEXT:  tee_local   $push1=, $0=, $pop0{{$}}
; CHECK-NEXT:  call        use_a@FUNCTION, $pop1{{$}}
; CHECK-NEXT:  call        use_b@FUNCTION, $0{{$}}
; CHECK-NEXT:  return{{$}}
declare void @use_a(i32)
declare void @use_b(i32)
define void @simple_multiple_use(i32 %x, i32 %y) {
  %mul = mul i32 %y, %x
  call void @use_a(i32 %mul)
  call void @use_b(i32 %mul)
  ret void
}

; Multiple uses of the same value in one instruction.

; CHECK-LABEL: multiple_uses_in_same_insn:
; CHECK-NEXT:  .param      i32, i32{{$}}
; CHECK-NEXT:  i32.mul     $push0=, $1, $0{{$}}
; CHECK-NEXT:  tee_local   $push1=, $0=, $pop0{{$}}
; CHECK-NEXT:  call        use_2@FUNCTION, $pop1, $0{{$}}
; CHECK-NEXT:  return{{$}}
declare void @use_2(i32, i32)
define void @multiple_uses_in_same_insn(i32 %x, i32 %y) {
  %mul = mul i32 %y, %x
  call void @use_2(i32 %mul, i32 %mul)
  ret void
}

; Commute operands to achieve better stackifying.

; CHECK-LABEL: commute:
; CHECK-NEXT:  .result     i32{{$}}
; CHECK-NEXT:  i32.call    $push0=, red@FUNCTION{{$}}
; CHECK-NEXT:  i32.call    $push1=, green@FUNCTION{{$}}
; CHECK-NEXT:  i32.add     $push2=, $pop0, $pop1{{$}}
; CHECK-NEXT:  i32.call    $push3=, blue@FUNCTION{{$}}
; CHECK-NEXT:  i32.add     $push4=, $pop2, $pop3{{$}}
; CHECK-NEXT:  return      $pop4{{$}}
declare i32 @red()
declare i32 @green()
declare i32 @blue()
define i32 @commute() {
  %call = call i32 @red()
  %call1 = call i32 @green()
  %add = add i32 %call1, %call
  %call2 = call i32 @blue()
  %add3 = add i32 %add, %call2
  ret i32 %add3
}

; Don't stackify a register when it would move a the def of the register past
; an implicit get_local for the register.

; CHECK-LABEL: no_stackify_past_use:
; CHECK: i32.call        $1=, callee@FUNCTION, $0
; CHECK: i32.const       $push0=, 1
; CHECK: i32.add         $push1=, $0, $pop0
; CHECK: i32.call        $push2=, callee@FUNCTION, $pop1
; CHECK: i32.add         $push3=, $1, $pop2
; CHECK: i32.mul         $push4=, $1, $pop3
; CHECK: return          $pop4
declare i32 @callee(i32)
define i32 @no_stackify_past_use(i32 %arg) {
  %tmp1 = call i32 @callee(i32 %arg)
  %tmp2 = add i32 %arg, 1
  %tmp3 = call i32 @callee(i32 %tmp2)
  %tmp5 = add i32 %tmp3, %tmp1
  %tmp6 = mul i32 %tmp5, %tmp1
  ret i32 %tmp6
}

!0 = !{}