Polymophic stack support (#1117)

Emit valid wasm binaries even for corner cases of unreachable code.

 * emit an unreachable after a node that pushes a value that has unreachable type (where wasm type checking would have pushed a concrete type)
 * conversely, as a hack, emulate the wasm polymorphic stack mode by not emptying the stack when it has one element and that element is unreachable. this lets further pops work (all returning an unreachable element)

6 files changed, 451 insertions, 0 deletions

diff --git a/test/polymorphic_stack.wast b/test/polymorphic_stack.wast
new file mode 100644
index 000000000..2241ab910
--- /dev/null
+++ b/test/polymorphic_stack.wast
@@ -0,0 +1,90 @@
+(module
+  (type $FUNCSIG$ii (func (param i32) (result i32)))
+  (import "env" "table" (table 9 9 anyfunc))
+  (func $break-and-binary (result i32)
+    (block $x (result i32)
+      (f32.add
+        (br_if $x
+          (i32.trunc_u/f64
+            (unreachable)
+          )
+          (i32.trunc_u/f64
+            (unreachable)
+          )
+        )
+        (f32.const 1)
+      )
+    )
+  )
+  (func $call-and-unary (param i32) (result i32)
+    (drop
+      (i64.eqz
+        (call $call-and-unary
+          (unreachable)
+        )
+      )
+    )
+    (drop
+      (i64.eqz
+        (i32.eqz
+          (unreachable)
+        )
+      )
+    )
+    (drop
+      (i64.eqz
+        (call_indirect $FUNCSIG$ii
+          (unreachable)
+          (unreachable)
+        )
+      )
+    )
+  )
+  (func $tee (param $x i32)
+    (local $y f32)
+    (drop
+      (i64.eqz
+        (tee_local $x
+          (unreachable)
+        )
+      )
+    )
+    (drop
+      (tee_local $y
+        (i64.eqz
+          (unreachable)
+        )
+      )
+    )
+  )
+  (func $tee2
+    (local $0 f32)
+    (if
+      (i32.const 259)
+      (set_local $0
+        (unreachable)
+      )
+    )
+  )
+  (func $select
+    (drop
+      (i64.eqz
+        (select
+          (unreachable)
+          (i32.const 1)
+          (i32.const 2)
+        )
+      )
+    )
+  )
+  (func $untaken-break-should-have-value (result i32)
+    (block $x (result i32)
+      (block
+        (br_if $x ;; ok to not have a value, since an untaken branch. but must emit valid binary for wasm
+          (unreachable)
+        )
+      )
+    )
+  )
+)
+
diff --git a/test/polymorphic_stack.wast.from-wast b/test/polymorphic_stack.wast.from-wast
new file mode 100644
index 000000000..b4b88f16b
--- /dev/null
+++ b/test/polymorphic_stack.wast.from-wast
@@ -0,0 +1,93 @@
+(module
+ (type $FUNCSIG$ii (func (param i32) (result i32)))
+ (type $1 (func (result i32)))
+ (type $2 (func (param i32)))
+ (type $3 (func))
+ (import "env" "table" (table 9 9 anyfunc))
+ (memory $0 0)
+ (func $break-and-binary (type $1) (result i32)
+  (block $x (result i32)
+   (f32.add
+    (br_if $x
+     (i32.trunc_u/f64
+      (unreachable)
+     )
+     (i32.trunc_u/f64
+      (unreachable)
+     )
+    )
+    (f32.const 1)
+   )
+  )
+ )
+ (func $call-and-unary (type $FUNCSIG$ii) (param $0 i32) (result i32)
+  (drop
+   (i64.eqz
+    (call $call-and-unary
+     (unreachable)
+    )
+   )
+  )
+  (drop
+   (i64.eqz
+    (i32.eqz
+     (unreachable)
+    )
+   )
+  )
+  (drop
+   (i64.eqz
+    (call_indirect $FUNCSIG$ii
+     (unreachable)
+     (unreachable)
+    )
+   )
+  )
+ )
+ (func $tee (type $2) (param $x i32)
+  (local $y f32)
+  (drop
+   (i64.eqz
+    (tee_local $x
+     (unreachable)
+    )
+   )
+  )
+  (drop
+   (tee_local $y
+    (i64.eqz
+     (unreachable)
+    )
+   )
+  )
+ )
+ (func $tee2 (type $3)
+  (local $0 f32)
+  (if
+   (i32.const 259)
+   (tee_local $0
+    (unreachable)
+   )
+  )
+ )
+ (func $select (type $3)
+  (drop
+   (i64.eqz
+    (select
+     (unreachable)
+     (i32.const 1)
+     (i32.const 2)
+    )
+   )
+  )
+ )
+ (func $untaken-break-should-have-value (type $1) (result i32)
+  (block $x (result i32)
+   (block $block
+    (br_if $x
+     (unreachable)
+    )
+   )
+  )
+ )
+)
diff --git a/test/polymorphic_stack.wast.fromBinary b/test/polymorphic_stack.wast.fromBinary
new file mode 100644
index 000000000..e0ee6577d
--- /dev/null
+++ b/test/polymorphic_stack.wast.fromBinary
@@ -0,0 +1,129 @@
+(module
+ (type $0 (func (param i32) (result i32)))
+ (type $1 (func (result i32)))
+ (type $2 (func (param i32)))
+ (type $3 (func))
+ (import "env" "table" (table 9 9 anyfunc))
+ (memory $0 0)
+ (func $break-and-binary (type $1) (result i32)
+  (block $label$0 (result i32)
+   (unreachable)
+   (i32.trunc_u/f64
+    (unreachable)
+   )
+   (unreachable)
+   (br_if $label$0
+    (i32.trunc_u/f64
+     (unreachable)
+    )
+    (unreachable)
+   )
+   (f32.add
+    (unreachable)
+    (f32.const 1)
+   )
+   (unreachable)
+  )
+ )
+ (func $call-and-unary (type $0) (param $var$0 i32) (result i32)
+  (block $label$0 (result i32)
+   (unreachable)
+   (call $call-and-unary
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (i32.eqz
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (call_indirect $0
+    (unreachable)
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+  )
+ )
+ (func $tee (type $2) (param $var$0 i32)
+  (local $var$1 f32)
+  (block $label$0
+   (unreachable)
+   (tee_local $var$0
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (tee_local $var$1
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (unreachable)
+  )
+  (unreachable)
+ )
+ (func $tee2 (type $3)
+  (local $var$0 f32)
+  (if
+   (i32.const 259)
+   (block $label$0
+    (unreachable)
+    (tee_local $var$0
+     (unreachable)
+    )
+    (unreachable)
+   )
+  )
+ )
+ (func $select (type $3)
+  (unreachable)
+  (select
+   (unreachable)
+   (i32.const 1)
+   (i32.const 2)
+  )
+  (i64.eqz
+   (unreachable)
+  )
+  (drop
+   (unreachable)
+  )
+ )
+ (func $untaken-break-should-have-value (type $1) (result i32)
+  (block $label$0 (result i32)
+   (block $label$1
+    (unreachable)
+    (br_if $label$0
+     (unreachable)
+     (unreachable)
+    )
+    (unreachable)
+    (unreachable)
+   )
+   (unreachable)
+  )
+ )
+)
+
diff --git a/test/polymorphic_stack.wast.fromBinary.noDebugInfo b/test/polymorphic_stack.wast.fromBinary.noDebugInfo
new file mode 100644
index 000000000..857a3660c
--- /dev/null
+++ b/test/polymorphic_stack.wast.fromBinary.noDebugInfo
@@ -0,0 +1,129 @@
+(module
+ (type $0 (func (param i32) (result i32)))
+ (type $1 (func (result i32)))
+ (type $2 (func (param i32)))
+ (type $3 (func))
+ (import "env" "table" (table 9 9 anyfunc))
+ (memory $0 0)
+ (func $0 (type $1) (result i32)
+  (block $label$0 (result i32)
+   (unreachable)
+   (i32.trunc_u/f64
+    (unreachable)
+   )
+   (unreachable)
+   (br_if $label$0
+    (i32.trunc_u/f64
+     (unreachable)
+    )
+    (unreachable)
+   )
+   (f32.add
+    (unreachable)
+    (f32.const 1)
+   )
+   (unreachable)
+  )
+ )
+ (func $1 (type $0) (param $var$0 i32) (result i32)
+  (block $label$0 (result i32)
+   (unreachable)
+   (call $1
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (i32.eqz
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (call_indirect $0
+    (unreachable)
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+  )
+ )
+ (func $2 (type $2) (param $var$0 i32)
+  (local $var$1 f32)
+  (block $label$0
+   (unreachable)
+   (tee_local $var$0
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (i64.eqz
+    (unreachable)
+   )
+   (tee_local $var$1
+    (unreachable)
+   )
+   (drop
+    (unreachable)
+   )
+   (unreachable)
+  )
+  (unreachable)
+ )
+ (func $3 (type $3)
+  (local $var$0 f32)
+  (if
+   (i32.const 259)
+   (block $label$0
+    (unreachable)
+    (tee_local $var$0
+     (unreachable)
+    )
+    (unreachable)
+   )
+  )
+ )
+ (func $4 (type $3)
+  (unreachable)
+  (select
+   (unreachable)
+   (i32.const 1)
+   (i32.const 2)
+  )
+  (i64.eqz
+   (unreachable)
+  )
+  (drop
+   (unreachable)
+  )
+ )
+ (func $5 (type $1) (result i32)
+  (block $label$0 (result i32)
+   (block $label$1
+    (unreachable)
+    (br_if $label$0
+     (unreachable)
+     (unreachable)
+    )
+    (unreachable)
+    (unreachable)
+   )
+   (unreachable)
+  )
+ )
+)
+
diff --git a/test/unit.wast.fromBinary b/test/unit.wast.fromBinary
index 7656dc7d7..78ae640b1 100644
--- a/test/unit.wast.fromBinary
+++ b/test/unit.wast.fromBinary
@@ -479,6 +479,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $unreachable-block-toplevel (type $5) (result i32)
   (block $label$0
@@ -502,6 +503,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $unreachable-block0-toplevel (type $5) (result i32)
   (block $label$0
@@ -540,6 +542,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $unreachable-if-toplevel (type $5) (result i32)
   (if
@@ -567,6 +570,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $unreachable-loop0 (type $5) (result i32)
   (loop $label$0
@@ -577,6 +581,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $unreachable-loop-toplevel (type $5) (result i32)
   (loop $label$0
diff --git a/test/unit.wast.fromBinary.noDebugInfo b/test/unit.wast.fromBinary.noDebugInfo
index bfcc12c6b..3c24886f5 100644
--- a/test/unit.wast.fromBinary.noDebugInfo
+++ b/test/unit.wast.fromBinary.noDebugInfo
@@ -479,6 +479,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $25 (type $5) (result i32)
   (block $label$0
@@ -502,6 +503,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $27 (type $5) (result i32)
   (block $label$0
@@ -540,6 +542,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $30 (type $5) (result i32)
   (if
@@ -567,6 +570,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $32 (type $5) (result i32)
   (loop $label$0
@@ -577,6 +581,7 @@
   (f64.abs
    (unreachable)
   )
+  (unreachable)
  )
  (func $33 (type $5) (result i32)
   (loop $label$0