[RT] Support expressions in element segments (#3666)

This PR adds support for `ref.null t` as a valid element segment
item. The abbreviated format of `(elem ... func $f $g...)` is kept in
both printing and binary emitting if all items are `ref.func`s. Public
APIs aren't updated in this PR.

9 files changed, 39 insertions, 9 deletions

diff --git a/test/multi-table.wast b/test/multi-table.wast
index 378d4018a..cbfa369e0 100644
--- a/test/multi-table.wast
+++ b/test/multi-table.wast
@@ -1,6 +1,7 @@
 (module
   (import "a" "b" (table $t1 1 10 funcref))
   (table $t2 3 3 funcref)
+  (table $t3 4 4 funcref)
 
   ;; add to $t1
   (elem (i32.const 0) $f)
@@ -9,7 +10,10 @@
   (elem (table $t2) (i32.const 0) func $f)
   (elem $activeNonZeroOffset (table $t2) (offset (i32.const 1)) func $f $g)
 
-  (elem $passive func $f $g)
+  (elem $e3-1 (table $t3) (i32.const 0) funcref (ref.func $f) (ref.null func))
+  (elem $e3-2 (table $t3) (offset (i32.const 2)) funcref (item ref.func $f) (item (ref.func $g)))
+
+  (elem $passive funcref (item ref.func $f) (item (ref.func $g)) (ref.null func))
   (elem $empty func)
   (elem $declarative declare func $h)
 
diff --git a/test/multi-table.wast.from-wast b/test/multi-table.wast.from-wast
index f60bab8cb..80c081354 100644
--- a/test/multi-table.wast.from-wast
+++ b/test/multi-table.wast.from-wast
@@ -5,7 +5,10 @@
  (table $t2 3 3 funcref)
  (elem (table $t2) (i32.const 0) func $f)
  (elem $activeNonZeroOffset (table $t2) (i32.const 1) func $f $g)
- (elem $passive func $f $g)
+ (table $t3 4 4 funcref)
+ (elem $e3-1 (table $t3) (i32.const 0) funcref (ref.func $f) (ref.null func))
+ (elem $e3-2 (table $t3) (i32.const 2) func $f $g)
+ (elem $passive funcref (ref.func $f) (ref.func $g) (ref.null func))
  (elem declare func $h)
  (func $f
   (drop
diff --git a/test/multi-table.wast.fromBinary b/test/multi-table.wast.fromBinary
index 13604e69d..9918b6183 100644
--- a/test/multi-table.wast.fromBinary
+++ b/test/multi-table.wast.fromBinary
@@ -5,7 +5,10 @@
  (table $t2 3 3 funcref)
  (elem (table $t2) (i32.const 0) func $f)
  (elem $activeNonZeroOffset (table $t2) (i32.const 1) func $f $g)
- (elem $passive func $f $g)
+ (table $t3 4 4 funcref)
+ (elem $e3-1 (table $t3) (i32.const 0) funcref (ref.func $f) (ref.null func))
+ (elem $e3-2 (table $t3) (i32.const 2) func $f $g)
+ (elem $passive funcref (ref.func $f) (ref.func $g) (ref.null func))
  (elem declare func $h)
  (func $f
   (drop
diff --git a/test/multi-table.wast.fromBinary.noDebugInfo b/test/multi-table.wast.fromBinary.noDebugInfo
index 77e2ea439..638ee7329 100644
--- a/test/multi-table.wast.fromBinary.noDebugInfo
+++ b/test/multi-table.wast.fromBinary.noDebugInfo
@@ -5,7 +5,10 @@
  (table $0 3 3 funcref)
  (elem (table $0) (i32.const 0) func $0)
  (elem (table $0) (i32.const 1) func $0 $1)
- (elem func $0 $1)
+ (table $1 4 4 funcref)
+ (elem (table $1) (i32.const 0) funcref (ref.func $0) (ref.null func))
+ (elem (table $1) (i32.const 2) func $0 $1)
+ (elem funcref (ref.func $0) (ref.func $1) (ref.null func))
  (elem declare func $2)
  (func $0
   (drop
diff --git a/test/passes/converge_O3_metrics.bin.txt b/test/passes/converge_O3_metrics.bin.txt
index 2df4a4b0b..4c1bed30d 100644
--- a/test/passes/converge_O3_metrics.bin.txt
+++ b/test/passes/converge_O3_metrics.bin.txt
@@ -7,7 +7,7 @@ total
  [memory-data]  : 28      
  [table-data]   : 429     
  [tables]       : 0       
- [total]        : 129     
+ [total]        : 558     
  [vars]         : 4       
  Binary         : 12      
  Block          : 8       
@@ -23,6 +23,7 @@ total
  LocalGet       : 18      
  LocalSet       : 7       
  Loop           : 1       
+ RefFunc        : 429     
  Store          : 5       
 (module
  (type $i32_i32_i32_=>_i32 (func (param i32 i32 i32) (result i32)))
@@ -249,7 +250,7 @@ total
  [memory-data]  : 28      
  [table-data]   : 429     
  [tables]       : 0       
- [total]        : 129     
+ [total]        : 558     
  [vars]         : 4       
  Binary         : 12      
  Block          : 8       
@@ -265,6 +266,7 @@ total
  LocalGet       : 18      
  LocalSet       : 7       
  Loop           : 1       
+ RefFunc        : 429     
  Store          : 5       
 (module
  (type $i32_i32_i32_=>_i32 (func (param i32 i32 i32) (result i32)))
diff --git a/test/passes/func-metrics.txt b/test/passes/func-metrics.txt
index 1ca5d2fd9..61d97ddad 100644
--- a/test/passes/func-metrics.txt
+++ b/test/passes/func-metrics.txt
@@ -7,8 +7,9 @@ global
  [memory-data]  : 9       
  [table-data]   : 3       
  [tables]       : 1       
- [total]        : 3       
+ [total]        : 6       
  Const          : 3       
+ RefFunc        : 3       
 func: empty
  [binary-bytes] : 3       
  [total]        : 1       
diff --git a/test/passes/fuzz_metrics_noprint.bin.txt b/test/passes/fuzz_metrics_noprint.bin.txt
index eb24adfa4..d2b5e37e9 100644
--- a/test/passes/fuzz_metrics_noprint.bin.txt
+++ b/test/passes/fuzz_metrics_noprint.bin.txt
@@ -7,7 +7,7 @@ total
  [memory-data]  : 4       
  [table-data]   : 17      
  [tables]       : 1       
- [total]        : 5797    
+ [total]        : 5814    
  [vars]         : 160     
  Binary         : 467     
  Block          : 810     
@@ -24,6 +24,7 @@ total
  LocalSet       : 292     
  Loop           : 127     
  Nop            : 69      
+ RefFunc        : 17      
  Return         : 259     
  Select         : 53      
  Store          : 53      
diff --git a/test/passes/metrics_all-features.txt b/test/passes/metrics_all-features.txt
index ae746355d..14c1bc72d 100644
--- a/test/passes/metrics_all-features.txt
+++ b/test/passes/metrics_all-features.txt
@@ -7,13 +7,14 @@ total
  [memory-data]  : 9       
  [table-data]   : 3       
  [tables]       : 1       
- [total]        : 27      
+ [total]        : 30      
  [vars]         : 1       
  Binary         : 1       
  Block          : 1       
  Const          : 15      
  Drop           : 6       
  If             : 4       
+ RefFunc        : 3       
 (module
  (type $0 (func (param i32)))
  (type $i32_i32_=>_none (func (param i32 i32)))
diff --git a/test/spec/call_indirect_refnull.wast b/test/spec/call_indirect_refnull.wast
new file mode 100644
index 000000000..f1b4f5978
--- /dev/null
+++ b/test/spec/call_indirect_refnull.wast
@@ -0,0 +1,12 @@
+(module
+  (table $t 1 1 funcref)
+  (elem (table $t) (i32.const 0) funcref (ref.null func))
+
+  (func $call-refnull (export "call-refnull") (result f32)
+    (call_indirect (result f32) (i32.const 0))
+  )
+)
+(assert_trap
+  (invoke "call-refnull")
+  "uninitialized table element"
+)
\ No newline at end of file