Restore and fix SpillPointers pass (#4570)

We have some possible use cases for this pass, and so are restoring
it.

This reverts the removal in #3261, fixes compile errors in internal API
changes since then, and flips the direction of the stack for the
wasm backend.

1 files changed, 338 insertions, 0 deletions

diff --git a/test/passes/spill-pointers.wast b/test/passes/spill-pointers.wast
new file mode 100644
index 000000000..4eb05a721
--- /dev/null
+++ b/test/passes/spill-pointers.wast
@@ -0,0 +1,338 @@
+(module
+  (memory 10)
+  (type $ii (func (param i32 i32)))
+  (table 1 1 funcref)
+  (elem (i32.const 0))
+  (import "env" "STACKTOP" (global $STACKTOP$asm2wasm$import i32))
+  (import "env" "segfault" (func $segfault (param i32)))
+  (global $stack_ptr (mut i32) (global.get $STACKTOP$asm2wasm$import))
+
+  (func $nothing
+  )
+  (func $not-alive
+    (local $x i32)
+    (local.set $x (i32.const 1))
+    (call $nothing)
+  )
+  (func $spill
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+  )
+  (func $ignore-non-pointers
+    (local $x i32)
+    (local $y i64)
+    (local $z f32)
+    (local $w f64)
+    (local.set $x (i32.const 1))
+    (local.set $y (i64.const 1))
+    (local.set $z (f32.const 1))
+    (local.set $w (f64.const 1))
+    (call $nothing)
+    (drop (local.get $x))
+    (drop (local.get $y))
+    (drop (local.get $z))
+    (drop (local.get $w))
+  )
+  (func $spill4
+    (local $x i32)
+    (local $y i32)
+    (local $z i32)
+    (local $w i32)
+    (local.set $x (i32.const 1))
+    (local.set $y (i32.const 1))
+    (local.set $z (i32.const 1))
+    (local.set $w (i32.const 1))
+    (call $nothing)
+    (drop (local.get $x))
+    (drop (local.get $y))
+    (drop (local.get $z))
+    (drop (local.get $w))
+  )
+  (func $spill5
+    (local $x i32)
+    (local $y i32)
+    (local $z i32)
+    (local $w i32)
+    (local $a i32)
+    (local.set $x (i32.const 1))
+    (local.set $y (i32.const 1))
+    (local.set $z (i32.const 1))
+    (local.set $w (i32.const 1))
+    (local.set $a (i32.const 1))
+    (call $nothing)
+    (drop (local.get $x))
+    (drop (local.get $y))
+    (drop (local.get $z))
+    (drop (local.get $w))
+    (drop (local.get $a))
+  )
+  (func $some-alive
+    (local $x i32)
+    (local $y i32)
+    (call $nothing)
+    (drop (local.get $x))
+  )
+  (func $spill-args (param $p i32) (param $q i32)
+    (local $x i32)
+    (call $spill-args (i32.const 1) (i32.const 2))
+    (drop (local.get $x))
+  )
+  (func $spill-ret (result i32)
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+    (if (i32.const 1)
+      (return (i32.const 2))
+      (return (i32.const 3))
+    )
+    (i32.const 4)
+  )
+  (func $spill-unreachable (result i32)
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+    (unreachable)
+  )
+  (func $spill-call-call0 (param $p i32) (result i32)
+    (unreachable)
+  )
+  (func $spill-call-call1 (param $p i32) (result i32)
+    (local $x i32)
+    (drop
+      (call $spill-call-call0
+        (call $spill-call-call1
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-call-ret (param $p i32) (result i32)
+    (local $x i32)
+    (drop
+      (call $spill-call-call0
+        (return
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-ret-call (param $p i32) (result i32)
+    (local $x i32)
+    (drop
+      (return
+        (call $spill-call-call0
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-ret-ret (result i32)
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+    (drop
+      (return
+        (return
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-call-othertype (param $y f64)
+    (local $x i32)
+    (call $spill-call-othertype (f64.const 1))
+    (drop (local.get $x))
+  )
+  (func $spill-call_indirect
+    (local $x i32)
+    (call_indirect (type $ii)
+      (i32.const 123)
+      (i32.const 456)
+      (i32.const 789)
+    )
+    (drop (local.get $x))
+  )
+  (func $spill-call_import
+    (local $x i32)
+    (call $segfault
+      (i32.const 200)
+    )
+    (drop (local.get $x))
+  )
+)
+
+(module
+  (memory 10)
+  (type $ii (func (param i32 i32)))
+  (table 1 1 funcref)
+  (elem (i32.const 0))
+  (global $stack_ptr (mut i32) (i32.const 1716592))
+  (export "stackSave" (func $stack_save))
+  (import "env" "segfault" (func $segfault (param i32)))
+  (func $stack_save (result i32)
+    (global.get $stack_ptr)
+  )
+
+  (func $nothing
+  )
+  (func $not-alive
+    (local $x i32)
+    (local.set $x (i32.const 1))
+    (call $nothing)
+  )
+  (func $spill
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+  )
+  (func $ignore-non-pointers
+    (local $x i32)
+    (local $y i64)
+    (local $z f32)
+    (local $w f64)
+    (local.set $x (i32.const 1))
+    (local.set $y (i64.const 1))
+    (local.set $z (f32.const 1))
+    (local.set $w (f64.const 1))
+    (call $nothing)
+    (drop (local.get $x))
+    (drop (local.get $y))
+    (drop (local.get $z))
+    (drop (local.get $w))
+  )
+  (func $spill4
+    (local $x i32)
+    (local $y i32)
+    (local $z i32)
+    (local $w i32)
+    (local.set $x (i32.const 1))
+    (local.set $y (i32.const 1))
+    (local.set $z (i32.const 1))
+    (local.set $w (i32.const 1))
+    (call $nothing)
+    (drop (local.get $x))
+    (drop (local.get $y))
+    (drop (local.get $z))
+    (drop (local.get $w))
+  )
+  (func $spill5
+    (local $x i32)
+    (local $y i32)
+    (local $z i32)
+    (local $w i32)
+    (local $a i32)
+    (local.set $x (i32.const 1))
+    (local.set $y (i32.const 1))
+    (local.set $z (i32.const 1))
+    (local.set $w (i32.const 1))
+    (local.set $a (i32.const 1))
+    (call $nothing)
+    (drop (local.get $x))
+    (drop (local.get $y))
+    (drop (local.get $z))
+    (drop (local.get $w))
+    (drop (local.get $a))
+  )
+  (func $some-alive
+    (local $x i32)
+    (local $y i32)
+    (call $nothing)
+    (drop (local.get $x))
+  )
+  (func $spill-args (param $p i32) (param $q i32)
+    (local $x i32)
+    (call $spill-args (i32.const 1) (i32.const 2))
+    (drop (local.get $x))
+  )
+  (func $spill-ret (result i32)
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+    (if (i32.const 1)
+      (return (i32.const 2))
+      (return (i32.const 3))
+    )
+    (i32.const 4)
+  )
+  (func $spill-unreachable (result i32)
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+    (unreachable)
+  )
+  (func $spill-call-call0 (param $p i32) (result i32)
+    (unreachable)
+  )
+  (func $spill-call-call1 (param $p i32) (result i32)
+    (local $x i32)
+    (drop
+      (call $spill-call-call0
+        (call $spill-call-call1
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-call-ret (param $p i32) (result i32)
+    (local $x i32)
+    (drop
+      (call $spill-call-call0
+        (return
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-ret-call (param $p i32) (result i32)
+    (local $x i32)
+    (drop
+      (return
+        (call $spill-call-call0
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-ret-ret (result i32)
+    (local $x i32)
+    (call $nothing)
+    (drop (local.get $x))
+    (drop
+      (return
+        (return
+          (i32.const 1)
+        )
+      )
+    )
+    (local.get $x)
+  )
+  (func $spill-call-othertype (param $y f64)
+    (local $x i32)
+    (call $spill-call-othertype (f64.const 1))
+    (drop (local.get $x))
+  )
+  (func $spill-call_indirect
+    (local $x i32)
+    (call_indirect (type $ii)
+      (i32.const 123)
+      (i32.const 456)
+      (i32.const 789)
+    )
+    (drop (local.get $x))
+  )
+  (func $spill-call_import
+    (local $x i32)
+    (call $segfault
+      (i32.const 200)
+    )
+    (drop (local.get $x))
+  )
+)