[reference-types] Support passive elem segments (#3572)

Passive element segments do not belong to any table, so the link between
Table and elem needs to be weaker; i.e. an elem may have a table in case
of active segments, or simply be a collection of function references in
case of passive/declarative segments.

This PR takes Table::Segment out and turns it into a first class module
element just like tables and functions. It also implements early support
for parsing, printing, encoding and decoding passive/declarative elem
segments.

4 files changed, 58 insertions, 30 deletions

diff --git a/test/example/c-api-kitchen-sink.c b/test/example/c-api-kitchen-sink.c
index 04f552069..fa23a47ce 100644
--- a/test/example/c-api-kitchen-sink.c
+++ b/test/example/c-api-kitchen-sink.c
@@ -320,7 +320,7 @@ void test_core() {
   BinaryenAddEvent(
     module, "a-event", 0, BinaryenTypeInt32(), BinaryenTypeNone());
 
-  BinaryenAddTable(module, "tab", 0, 100, NULL, 0, makeInt32(module, 0));
+  BinaryenAddTable(module, "tab", 0, 100);
 
   // Exception handling
 
@@ -855,7 +855,17 @@ void test_core() {
 
   // Function table. One per module
   const char* funcNames[] = { BinaryenFunctionGetName(sinker) };
-  BinaryenSetFunctionTable(module, 1, 1, funcNames, 1, BinaryenConst(module, BinaryenLiteralInt32(0)));
+  BinaryenAddTable(module, "0", 1, 1);
+  BinaryenAddActiveElementSegment(
+    module,
+    "0",
+    "0",
+    funcNames,
+    1,
+    BinaryenConst(module, BinaryenLiteralInt32(0)));
+  BinaryenAddPassiveElementSegment(module, "passive", funcNames, 1);
+  BinaryenAddPassiveElementSegment(module, "p2", funcNames, 1);
+  BinaryenRemoveElementSegment(module, "p2");
 
   // Memory. One per module
 
@@ -1382,14 +1392,15 @@ void test_for_each() {
       BinaryenFunctionGetName(fns[2])
     };
     BinaryenExpressionRef constExprRef = BinaryenConst(module, BinaryenLiteralInt32(0));
-    BinaryenSetFunctionTable(module, 1, 1, funcNames, 3, constExprRef);
-    assert(0 == BinaryenIsFunctionTableImported(module));
-    assert(1 == BinaryenGetNumFunctionTableSegments(module));
-    assert(constExprRef == BinaryenGetFunctionTableSegmentOffset(module, 0));
-    assert(3 == BinaryenGetFunctionTableSegmentLength(module, 0));
-    for (i = 0; i != BinaryenGetFunctionTableSegmentLength(module, 0); ++i)
-    {
-      const char * str = BinaryenGetFunctionTableSegmentData(module, 0, i);
+    BinaryenAddTable(module, "0", 1, 1);
+    BinaryenAddActiveElementSegment(
+      module, "0", "0", funcNames, 3, constExprRef);
+    assert(1 == BinaryenGetNumElementSegments(module));
+    BinaryenElementSegmentRef segment =
+      BinaryenGetElementSegmentByIndex(module, 0);
+    assert(constExprRef == BinaryenElementSegmentGetOffset(segment));
+    for (i = 0; i != BinaryenElementSegmentGetLength(segment); ++i) {
+      const char* str = BinaryenElementSegmentGetData(segment, i);
       assert(0 == strcmp(funcNames[i], str));
     }
   }
diff --git a/test/example/c-api-kitchen-sink.txt b/test/example/c-api-kitchen-sink.txt
index 40b7da26e..761b08c85 100644
--- a/test/example/c-api-kitchen-sink.txt
+++ b/test/example/c-api-kitchen-sink.txt
@@ -39,8 +39,10 @@ BinaryenFeatureAll: 8191
  (memory $0 (shared 1 256))
  (data (i32.const 10) "hello, world")
  (data passive "I am passive")
- (table $tab 1 1 funcref)
- (elem (i32.const 0) "$kitchen()sinker")
+ (table $tab 0 100 funcref)
+ (table $0 1 1 funcref)
+ (elem $0 (table $0) (i32.const 0) func "$kitchen()sinker")
+ (elem $passive func "$kitchen()sinker")
  (global $a-global i32 (i32.const 7))
  (global $a-mutable-global (mut f32) (f32.const 7.5))
  (event $a-event (attr 0) (param i32))
@@ -2461,7 +2463,7 @@ validation: 0
  (data (i32.const 10) "hello, world")
  (data (global.get $a-global) "segment data 2")
  (table $0 1 1 funcref)
- (elem (i32.const 0) $fn0 $fn1 $fn2)
+ (elem $0 (i32.const 0) $fn0 $fn1 $fn2)
  (global $a-global i32 (i32.const 125))
  (export "export0" (func $fn0))
  (export "export1" (func $fn1))
diff --git a/test/example/c-api-multiple-tables.c b/test/example/c-api-multiple-tables.c
index 625af444c..c19dcdb6f 100644
--- a/test/example/c-api-multiple-tables.c
+++ b/test/example/c-api-multiple-tables.c
@@ -31,28 +31,42 @@ int main() {
       BinaryenAddFunction(module, "adder", params, results, NULL, 0, add);
 
     const char* funcNames[] = {"adder"};
-    BinaryenAddTable(module,
-                     "tab",
-                     1,
-                     1,
-                     funcNames,
-                     1,
-                     BinaryenConst(module, BinaryenLiteralInt32(0)));
+    BinaryenAddTable(module, "tab", 1, 1);
     assert(BinaryenGetTable(module, "tab") != NULL);
-
-    BinaryenAddTable(module,
-                     "t2",
-                     1,
-                     1,
-                     funcNames,
-                     1,
-                     BinaryenConst(module, BinaryenLiteralInt32(0)));
+    BinaryenAddActiveElementSegment(
+      module,
+      "tab",
+      "0",
+      funcNames,
+      1,
+      BinaryenConst(module, BinaryenLiteralInt32(0)));
+
+    BinaryenAddTable(module, "t2", 1, 1);
+    BinaryenAddActiveElementSegment(
+      module,
+      "t2",
+      "1",
+      funcNames,
+      1,
+      BinaryenConst(module, BinaryenLiteralInt32(0)));
+    BinaryenAddPassiveElementSegment(module, "passive", funcNames, 1);
+    assert(NULL != BinaryenGetElementSegmentByIndex(module, 2));
+    assert(1 == BinayenElementSegmentIsPassive(
+                  BinaryenGetElementSegment(module, "passive")));
     BinaryenTableRef t2 = BinaryenGetTableByIndex(module, 1);
     assert(t2 != NULL);
+    BinaryenElementSegmentRef elem1 = BinaryenGetElementSegment(module, "1");
+    assert(elem1 != NULL);
+    assert(strcmp(BinaryenElementSegmentGetName(elem1), "1") == 0);
+    assert(strcmp(BinaryenElementSegmentGetTable(elem1), "t2") == 0);
+    assert(BinaryenElementSegmentGetLength(elem1) == 1);
+    assert(strcmp(BinaryenElementSegmentGetData(elem1, 0), funcNames[0]) == 0);
 
     assert(strcmp(BinaryenTableGetName(t2), "t2") == 0);
     BinaryenTableSetName(t2, "table2");
     assert(strcmp(BinaryenTableGetName(t2), "table2") == 0);
+    BinaryenElementSegmentSetTable(elem1, "table2");
+    assert(strcmp(BinaryenElementSegmentGetTable(elem1), "table2") == 0);
     assert(BinaryenTableGetInitial(t2) == 1);
     BinaryenTableSetInitial(t2, 2);
     assert(BinaryenTableGetInitial(t2) == 2);
diff --git a/test/example/c-api-multiple-tables.txt b/test/example/c-api-multiple-tables.txt
index 5b2858e91..8a2963729 100644
--- a/test/example/c-api-multiple-tables.txt
+++ b/test/example/c-api-multiple-tables.txt
@@ -1,9 +1,10 @@
 (module
  (type $i32_i32_=>_i32 (func (param i32 i32) (result i32)))
  (table $tab 1 1 funcref)
- (elem (table $tab) (i32.const 0) func $adder)
+ (elem $0 (table $tab) (i32.const 0) func $adder)
  (table $table2 2 2 funcref)
- (elem (table $table2) (i32.const 0) func $adder)
+ (elem $1 (table $table2) (i32.const 0) func $adder)
+ (elem $passive func $adder)
  (func $adder (param $0 i32) (param $1 i32) (result i32)
   (i32.add
    (local.get $0)