Add support for multi-value proposal (#861)

Use the `--enable-multi-value` flag to enable.

A lot of code already "worked" with multi-value, and just needed to
remove the restrictions. Most of the other changes are modifying the
callback APIs to be more general, e.g. taking more than 1 result type.

* Types are now stored as the negative values; this works nicely with
  the encoding of inline function types (used for block signatures),
  which are always positive values.
* Remove `BlockSignature` and use `BlockDeclaration` instead, which
  is just a typedef to `FuncSignature`. This allows for explicit or
  implicit type specifications on the block signatures.
* Allow for >1 "keep" values in the DropKeep interpreter instruction

7 files changed, 345 insertions, 3 deletions

diff --git a/test/typecheck/bad-block-multi-mismatch.txt b/test/typecheck/bad-block-multi-mismatch.txt
new file mode 100644
index 00000000..5c73842c
--- /dev/null
+++ b/test/typecheck/bad-block-multi-mismatch.txt
@@ -0,0 +1,58 @@
+;;; TOOL: wat2wasm
+;;; ARGS: --enable-multi-value
+;;; ERROR: 1
+(module
+  ;; too few results
+  (func
+    block (result i32 i32)
+      i32.const 0
+    end
+    return)
+
+  ;; too many results
+  (func
+    block (result i32 i32)
+      i32.const 0
+      i32.const 0
+      i32.const 0
+    end
+    return)
+
+  ;; result type mismatch
+  (func
+    block (result f32 i32)
+      i32.const 0
+      i32.const 1
+    end
+    return)
+
+  ;; too few params
+  (func
+    block (param i32)
+      drop
+    end)
+
+  ;; param type mismatch
+  (func
+    f32.const 0
+    block (param i32)
+      drop
+    end)
+)
+(;; STDERR ;;;
+out/test/typecheck/bad-block-multi-mismatch.txt:9:5: error: type mismatch in block, expected [i32, i32] but got [i32]
+    end
+    ^^^
+out/test/typecheck/bad-block-multi-mismatch.txt:18:5: error: type mismatch in block, expected [] but got [i32]
+    end
+    ^^^
+out/test/typecheck/bad-block-multi-mismatch.txt:26:5: error: type mismatch in block, expected [f32, i32] but got [i32, i32]
+    end
+    ^^^
+out/test/typecheck/bad-block-multi-mismatch.txt:31:5: error: type mismatch in block, expected [i32] but got []
+    block (param i32)
+    ^^^^^
+out/test/typecheck/bad-block-multi-mismatch.txt:38:5: error: type mismatch in block, expected [i32] but got [f32]
+    block (param i32)
+    ^^^^^
+;;; STDERR ;;)
diff --git a/test/typecheck/bad-expr-if.txt b/test/typecheck/bad-expr-if.txt
index 453c832a..efcf54f3 100644
--- a/test/typecheck/bad-expr-if.txt
+++ b/test/typecheck/bad-expr-if.txt
@@ -13,7 +13,4 @@
 out/test/typecheck/bad-expr-if.txt:11:5: error: type mismatch in i32.add, expected [i32, i32] but got [i32]
     i32.add))
     ^^^^^^^
-out/test/typecheck/bad-expr-if.txt:11:5: error: type mismatch in function, expected [] but got [i32]
-    i32.add))
-    ^^^^^^^
 ;;; STDERR ;;)
diff --git a/test/typecheck/bad-if-multi-mismatch.txt b/test/typecheck/bad-if-multi-mismatch.txt
new file mode 100644
index 00000000..5008f669
--- /dev/null
+++ b/test/typecheck/bad-if-multi-mismatch.txt
@@ -0,0 +1,85 @@
+;;; TOOL: wat2wasm
+;;; ARGS: --enable-multi-value
+;;; ERROR: 1
+(module
+  ;; too many results
+  (func
+    i32.const 0
+    if (result i32 i64)
+      i32.const 0
+      i32.const 0
+      i64.const 0
+    else
+      i32.const 0
+      i32.const 0
+      i64.const 0
+    end
+    return)
+
+  ;; too few results
+  (func
+    i32.const 0
+    if (result i32 f64)
+      f64.const 0
+    else
+      f64.const 0
+    end
+    return)
+
+  ;; result type mismatch
+  (func
+    i32.const 0
+    if (result i32 f64)
+      f32.const 0
+      f64.const 0
+    else
+      f32.const 0
+      f64.const 0
+    end
+    return)
+
+  ;; too few params
+  (func
+    i32.const 0
+    if (param i32)
+      drop
+    else
+      drop
+    end)
+
+  ;; param type mismatch
+  (func
+    f32.const 0
+    i32.const 0
+    if (param i32)
+      drop
+    else
+      drop
+    end)
+)
+(;; STDERR ;;;
+out/test/typecheck/bad-if-multi-mismatch.txt:11:7: error: type mismatch in if true branch, expected [] but got [i32]
+      i64.const 0
+      ^^^^^^^^^
+out/test/typecheck/bad-if-multi-mismatch.txt:16:5: error: type mismatch in if false branch, expected [] but got [i32]
+    end
+    ^^^
+out/test/typecheck/bad-if-multi-mismatch.txt:23:7: error: type mismatch in if true branch, expected [i32, f64] but got [f64]
+      f64.const 0
+      ^^^^^^^^^
+out/test/typecheck/bad-if-multi-mismatch.txt:26:5: error: type mismatch in if false branch, expected [i32, f64] but got [f64]
+    end
+    ^^^
+out/test/typecheck/bad-if-multi-mismatch.txt:34:7: error: type mismatch in if true branch, expected [i32, f64] but got [f32, f64]
+      f64.const 0
+      ^^^^^^^^^
+out/test/typecheck/bad-if-multi-mismatch.txt:38:5: error: type mismatch in if false branch, expected [i32, f64] but got [f32, f64]
+    end
+    ^^^
+out/test/typecheck/bad-if-multi-mismatch.txt:44:5: error: type mismatch in if, expected [i32] but got []
+    if (param i32)
+    ^^
+out/test/typecheck/bad-if-multi-mismatch.txt:54:5: error: type mismatch in if, expected [i32] but got [f32]
+    if (param i32)
+    ^^
+;;; STDERR ;;)
diff --git a/test/typecheck/bad-loop-multi-mismatch.txt b/test/typecheck/bad-loop-multi-mismatch.txt
new file mode 100644
index 00000000..1592aa4c
--- /dev/null
+++ b/test/typecheck/bad-loop-multi-mismatch.txt
@@ -0,0 +1,58 @@
+;;; TOOL: wat2wasm
+;;; ARGS: --enable-multi-value
+;;; ERROR: 1
+(module
+  ;; too few results
+  (func
+    loop (result i32 i32)
+      i32.const 0
+    end
+    return)
+
+  ;; too many results
+  (func
+    loop (result i32 i32)
+      i32.const 0
+      i32.const 0
+      i32.const 0
+    end
+    return)
+
+  ;; result type mismatch
+  (func
+    loop (result f32 i32)
+      i32.const 0
+      i32.const 1
+    end
+    return)
+
+  ;; too few params
+  (func
+    loop (param i32)
+      drop
+    end)
+
+  ;; param type mismatch
+  (func
+    f32.const 0
+    loop (param i32)
+      drop
+    end)
+)
+(;; STDERR ;;;
+out/test/typecheck/bad-loop-multi-mismatch.txt:9:5: error: type mismatch in loop, expected [i32, i32] but got [i32]
+    end
+    ^^^
+out/test/typecheck/bad-loop-multi-mismatch.txt:18:5: error: type mismatch in loop, expected [] but got [i32]
+    end
+    ^^^
+out/test/typecheck/bad-loop-multi-mismatch.txt:26:5: error: type mismatch in loop, expected [f32, i32] but got [i32, i32]
+    end
+    ^^^
+out/test/typecheck/bad-loop-multi-mismatch.txt:31:5: error: type mismatch in loop, expected [i32] but got []
+    loop (param i32)
+    ^^^^
+out/test/typecheck/bad-loop-multi-mismatch.txt:38:5: error: type mismatch in loop, expected [i32] but got [f32]
+    loop (param i32)
+    ^^^^
+;;; STDERR ;;)
diff --git a/test/typecheck/br-multi.txt b/test/typecheck/br-multi.txt
new file mode 100644
index 00000000..9457d9fd
--- /dev/null
+++ b/test/typecheck/br-multi.txt
@@ -0,0 +1,42 @@
+;;; TOOL: wat2wasm
+;;; ARGS: --enable-multi-value
+(module
+  ;; block
+  (func
+    block (result i32 i64)
+      i32.const 1
+      i64.const 2
+      br 0
+    end
+    return)
+
+  ;; loop
+  (func
+    loop (result i32 i64)
+      br 0
+    end
+    return)
+
+  ;; loop w/ param
+  (func
+    i32.const 1
+    loop (param i32)
+      drop         ;; drop loop param
+      i32.const 2  ;; push loop param for br
+      br 0
+    end)
+
+  ;; if
+  (func
+    i32.const 1
+    if (result i32 i64)
+      i32.const 1
+      i64.const 2
+      br 0
+    else
+      i32.const 3
+      i64.const 4
+      br 0
+    end
+    return)
+)
diff --git a/test/typecheck/brif-multi.txt b/test/typecheck/brif-multi.txt
new file mode 100644
index 00000000..afda493e
--- /dev/null
+++ b/test/typecheck/brif-multi.txt
@@ -0,0 +1,50 @@
+;;; TOOL: wat2wasm
+;;; ARGS: --enable-multi-value
+(module
+  ;; block
+  (func
+    block (result i32 i64)
+      i32.const 1
+      i64.const 2
+      i32.const 0  ;; cond
+      br_if 0
+    end
+    return)
+
+  ;; loop
+  (func
+    loop (result i32 i64)
+      i32.const 0  ;; cond
+      br_if 0
+      i32.const 1
+      i64.const 2
+    end
+    return)
+
+  ;; loop w/ param
+  (func
+    i32.const 1
+    loop (param i32)
+      drop         ;; drop loop param
+      i32.const 2  ;; push loop param for br
+      i32.const 0  ;; cond
+      br_if 0
+      drop         ;; drop `i32.const 2`
+    end)
+
+  ;; if
+  (func
+    i32.const 1
+    if (result i32 i64)
+      i32.const 1
+      i64.const 2
+      i32.const 0  ;; cond
+      br_if 0
+    else
+      i32.const 3
+      i64.const 4
+      i32.const 0  ;; cond
+      br_if 0
+    end
+    return)
+)
diff --git a/test/typecheck/brtable-multi.txt b/test/typecheck/brtable-multi.txt
new file mode 100644
index 00000000..9ed7bdd0
--- /dev/null
+++ b/test/typecheck/brtable-multi.txt
@@ -0,0 +1,52 @@
+;;; TOOL: wat2wasm
+;;; ARGS: --enable-multi-value
+(module
+  ;; block
+  (func
+    block (result f32 f32)
+      block
+        block (result f32 f32)
+          f32.const 1
+          f32.const 2
+          i32.const 0  ;; key
+          br_table 0 2
+        end
+        drop
+        drop
+      end
+      f32.const 3
+      f32.const 4
+    end
+    return)
+
+  ;; loop
+  (func
+    loop (result f32 f32)
+      loop
+        loop (result f32 f32)
+          i32.const 0  ;; key
+          br_table 0 2
+        end
+        drop
+        drop
+      end
+      f32.const 3
+      f32.const 4
+    end
+    return)
+
+  ;; loop w/ param
+  (func
+    i32.const 1
+    loop (param i32)
+      drop  ;; loop param
+      loop
+        i32.const 2
+        loop (param i32)
+          ;; br param is passed through as loop param
+          i32.const 0  ;; key
+          br_table 0 2
+        end
+      end
+    end)
+)