[wasm-split] Run RemoveUnusedElements on secondary modules

src/ir/module-splitting.cpp

@@ -316,6 +316,7 @@ struct ModuleSplitter {
   void exportImportCalledPrimaryFunctions();
   void setupTablePatching();
   void shareImportableItems();
+  void removeUnusedSecondaryElements();
 
   ModuleSplitter(Module& primary, const Config& config)
     : config(config), secondaryPtr(initSecondary(primary)), primary(primary),
@@ -334,6 +335,7 @@ struct ModuleSplitter {
     exportImportCalledPrimaryFunctions();
     setupTablePatching();
     shareImportableItems();
+    removeUnusedSecondaryElements();
   }
 };
 
@@ -872,6 +874,15 @@ void ModuleSplitter::shareImportableItems() {
   }
 }
 
+void ModuleSplitter::removeUnusedSecondaryElements() {
+  // TODO: It would be better to be more selective about only exporting and
+  // importing those items that the secondary module needs. This would reduce
+  // code size in the primary module as well.
+  PassRunner runner(&secondary);
+  runner.add("remove-unused-module-elements");
+  runner.run();
+}
+
 } // anonymous namespace
 
 Results splitFunctions(Module& primary, const Config& config) {

src/tools/wasm-split/wasm-split.cpp

@@ -69,11 +69,15 @@ uint64_t hashFile(const std::string& filename) {
   return uint64_t(digest);
 }
 
-void adjustTableSize(Module& wasm, int initialSize) {
+void adjustTableSize(Module& wasm, int initialSize, bool secondary = false) {
   if (initialSize < 0) {
     return;
   }
   if (wasm.tables.empty()) {
+    if (secondary) {
+      // It's not a problem if the table is not used in the secondary module.
+      return;
+    }
     Fatal() << "--initial-table used but there is no table";
   }
 
@@ -336,7 +340,7 @@ void splitModule(const WasmSplitOptions& options) {
   auto& secondary = splitResults.secondary;
 
   adjustTableSize(wasm, options.initialTableSize);
-  adjustTableSize(*secondary, options.initialTableSize);
+  adjustTableSize(*secondary, options.initialTableSize, /*secondary=*/true);
 
   if (options.symbolMap) {
     writeSymbolMap(wasm, options.primaryOutput + ".symbols");
@@ -435,9 +439,6 @@ void multiSplitModule(const WasmSplitOptions& options) {
     // TODO: symbolMap, placeholderMap, emitModuleNames
     // TODO: Support --emit-text and use .wast in that case.
     auto moduleName = options.outPrefix + mod + ".wasm";
-    PassRunner runner(&*splitResults.secondary);
-    runner.add("remove-unused-module-elements");
-    runner.run();
     writeModule(*splitResults.secondary, moduleName, options);
   }
   writeModule(wasm, options.output, options);

test/example/module-splitting.txt

@@ -33,11 +33,6 @@ After:
 )
 Secondary:
 (module
- (type $0 (func (param i32)))
- (import "primary" "%memory" (memory $mem 3 42 shared))
- (import "primary" "%table" (table $tab 3 42 funcref))
- (import "primary" "%global" (global $glob (mut i32)))
- (import "primary" "%tag" (tag $e (param i32)))
 )
 
 
@@ -64,11 +59,6 @@ After:
 )
 Secondary:
 (module
- (type $0 (func (param i32)))
- (import "primary" "%memory" (memory $mem 3 42 shared))
- (import "primary" "%table" (table $tab 3 42 funcref))
- (import "primary" "%global" (global $glob (mut i32)))
- (import "primary" "%tag" (tag $e (param i32)))
 )
 
 
@@ -99,11 +89,6 @@ After:
 )
 Secondary:
 (module
- (type $0 (func (param i32)))
- (import "primary" "mem" (memory $mem 3 42 shared))
- (import "primary" "tab" (table $tab 3 42 funcref))
- (import "primary" "glob" (global $glob (mut i32)))
- (import "primary" "e" (tag $e (param i32)))
 )
 
 
@@ -171,7 +156,6 @@ After:
 )
 Secondary:
 (module
- (import "primary" "%table" (table $table 1 funcref))
 )
 
 
@@ -197,7 +181,6 @@ After:
 )
 Secondary:
 (module
- (import "primary" "%table" (table $table 2 funcref))
 )
 
 
@@ -226,8 +209,6 @@ After:
 )
 Secondary:
 (module
- (import "primary" "%table" (table $table 1 funcref))
- (import "primary" "%global" (global $base i32))
 )
 
 
@@ -256,8 +237,6 @@ After:
 )
 Secondary:
 (module
- (import "primary" "%table" (table $table 2 funcref))
- (import "primary" "%global" (global $base i32))
 )
 
 
@@ -297,7 +276,6 @@ After:
 )
 Secondary:
 (module
- (import "primary" "%table" (table $table 1000 funcref))
 )
 
 
@@ -324,8 +302,6 @@ After:
 )
 Secondary:
 (module
- (import "primary" "%table" (table $table 1000 funcref))
- (import "primary" "%global" (global $base i32))
 )
 
 
@@ -342,10 +318,6 @@ After:
 )
 Secondary:
 (module
- (type $0 (func (param i32) (result i32)))
- (func $foo (type $0) (param $0 i32) (result i32)
-  (local.get $0)
- )
 )
 
 
@@ -415,8 +387,7 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_1" (table $0 1 funcref))
- (import "primary" "%table" (table $table 1 funcref))
- (elem $0 (table $0) (i32.const 0) func $foo)
+ (elem $0 (i32.const 0) $foo)
  (func $foo (type $0) (param $0 i32) (result i32)
   (local.get $0)
  )
@@ -454,8 +425,7 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_1" (table $0 1 funcref))
- (import "primary" "%table" (table $table 2 funcref))
- (elem $0 (table $0) (i32.const 0) func $foo)
+ (elem $0 (i32.const 0) $foo)
  (func $foo (type $0) (param $0 i32) (result i32)
   (local.get $0)
  )
@@ -501,8 +471,7 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_2" (table $0 1 funcref))
- (import "primary" "%table" (table $table 1000 funcref))
- (elem $0 (table $0) (i32.const 0) func $foo)
+ (elem $0 (i32.const 0) $foo)
  (func $foo (type $0) (param $0 i32) (result i32)
   (local.get $0)
  )
@@ -551,9 +520,7 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_2" (table $0 1 funcref))
- (import "primary" "%table" (table $table 1000 funcref))
- (import "primary" "%global" (global $base i32))
- (elem $0 (table $0) (i32.const 0) func $foo)
+ (elem $0 (i32.const 0) $foo)
  (func $foo (type $0) (param $0 i32) (result i32)
   (local.get $0)
  )
@@ -602,9 +569,7 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_2" (table $0 1 funcref))
- (import "primary" "%table" (table $table 1000 funcref))
- (import "primary" "%global" (global $base i32))
- (elem $0 (table $0) (i32.const 0) func $foo)
+ (elem $0 (i32.const 0) $foo)
  (func $foo (type $0) (param $0 i32) (result i32)
   (local.get $0)
  )
@@ -661,9 +626,7 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_2" (table $0 1 funcref))
- (import "primary" "%table" (table $table 1000 funcref))
- (import "primary" "%global" (global $base i32))
- (elem $0 (table $0) (i32.const 0) func $foo)
+ (elem $0 (i32.const 0) $foo)
  (func $foo (type $0) (param $0 i32) (result i32)
   (local.get $0)
  )
@@ -717,11 +680,6 @@ After:
 )
 Secondary:
 (module
- (type $0 (func))
- (import "primary" "%bar" (func $bar (type $0)))
- (func $foo (type $0)
-  (call $bar)
- )
 )
 
 
@@ -776,13 +734,6 @@ After:
 )
 Secondary:
 (module
- (type $0 (func))
- (func $bar (type $0)
-  (nop)
- )
- (func $foo (type $0)
-  (call $bar)
- )
 )
 
 
@@ -879,8 +830,7 @@ Secondary:
 (module
  (type $0 (func))
  (import "primary" "%table_1" (table $0 2 funcref))
- (import "primary" "%table" (table $table 4 funcref))
- (elem $0 (table $0) (i32.const 0) func $foo $baz)
+ (elem $0 (i32.const 0) $foo $baz)
  (func $baz (type $0)
   (nop)
  )
@@ -944,9 +894,7 @@ Secondary:
 (module
  (type $0 (func))
  (import "primary" "%table_1" (table $0 2 funcref))
- (import "primary" "%table" (table $table 4 funcref))
- (import "primary" "%global" (global $base i32))
- (elem $0 (table $0) (i32.const 0) func $foo $baz)
+ (elem $0 (i32.const 0) $foo $baz)
  (func $baz (type $0)
   (nop)
  )
@@ -1010,8 +958,7 @@ Secondary:
 (module
  (type $0 (func))
  (import "primary" "%table_1" (table $0 3 funcref))
- (import "primary" "%table" (table $table 4 funcref))
- (elem $0 (table $0) (i32.const 0) func $foo $bar $quux)
+ (elem $0 (i32.const 0) $foo $bar $quux)
  (func $bar (type $0)
   (nop)
  )
@@ -1081,9 +1028,7 @@ Secondary:
 (module
  (type $0 (func))
  (import "primary" "%table_1" (table $0 3 funcref))
- (import "primary" "%table" (table $table 4 funcref))
- (import "primary" "%global" (global $base i32))
- (elem $0 (table $0) (i32.const 0) func $foo $bar $quux)
+ (elem $0 (i32.const 0) $foo $bar $quux)
  (func $bar (type $0)
   (nop)
  )
@@ -1136,10 +1081,8 @@ Secondary:
 (module
  (type $0 (func))
  (import "primary" "%table_2" (table $0 1 funcref))
- (import "primary" "%table" (table $table 2 funcref))
- (import "primary" "%global" (global $base i32))
  (import "primary" "%foo" (func $foo (type $0)))
- (elem $0 (table $0) (i32.const 0) func $bar)
+ (elem $0 (i32.const 0) $bar)
  (func $bar (type $0)
   (call $foo)
  )
@@ -1185,9 +1128,8 @@ Secondary:
 (module
  (type $0 (func (param i32) (result i32)))
  (import "primary" "%table_2" (table $0 1 funcref))
- (import "primary" "%table" (table $table 1 1 funcref))
  (import "primary" "%foo" (func $foo (type $0) (param i32) (result i32)))
- (elem $0 (table $0) (i32.const 0) func $bar)
+ (elem $0 (i32.const 0) $bar)
  (func $bar (type $0) (param $0 i32) (result i32)
   (call $foo
    (i32.const 1)
@@ -1279,28 +1221,5 @@ Minimized names primary:
 
 Minimized names secondary:
 (module
- (type $0 (func))
- (import "primary" "%a" (func $0 (type $0)))
- (import "primary" "%c" (func $1 (type $0)))
- (import "primary" "%d" (func $2 (type $0)))
- (import "primary" "already_exported" (func $3 (type $0)))
- (import "primary" "%e" (func $4 (type $0)))
- (import "primary" "%f" (func $5 (type $0)))
- (import "primary" "%g" (func $6 (type $0)))
- (import "primary" "%b" (func $7 (type $0)))
- (import "primary" "%h" (func $8 (type $0)))
- (import "primary" "%i" (func $9 (type $0)))
- (func $call (type $0)
-  (call $0)
-  (call $1)
-  (call $2)
-  (call $3)
-  (call $4)
-  (call $5)
-  (call $6)
-  (call $7)
-  (call $8)
-  (call $9)
- )
 )
 

test/lit/wasm-split/basic.wast

@@ -174,7 +174,6 @@
 ;; KEEP-BOTH-PRIMARY-NEXT: )
 
 ;; KEEP-BOTH-SECONDARY:      (module
-;; KEEP-BOTH-SECONDARY-NEXT:  (import "primary" "%table" (table $table 1 1 funcref))
 ;; KEEP-BOTH-SECONDARY-NEXT: )
 
 ;; SPLIT-BAR-SUPERSEDE: warning: function bar was to be kept in primary module. However it will now be split out into secondary module.

test/lit/wasm-split/initial-table-used.wast

@@ -0,0 +1,22 @@
+;; Test that the --initial-table flag works as expected when the secondary
+;; module uses the table.
+
+;; RUN: wasm-split %s --instrument --initial-table=1234 -S | filecheck %s
+
+;; RUN: wasm-split %s -g -o1 %t.1.wasm -o2 %t.2.wasm --split-funcs=use-table --initial-table=1234
+;; RUN: wasm-dis %t.1.wasm | filecheck %s
+;; RUN: wasm-dis %t.2.wasm | filecheck %s
+
+;; CHECK: (table $table 1234 funcref)
+
+(module
+ (table $table 3 funcref)
+ (func $use-table
+  (call_indirect
+   (i32.const 0)
+  )
+ )
+ (func $use-use-table
+  (call $use-table)
+ )
+)

test/lit/wasm-split/initial-table.wast

@@ -1,10 +1,9 @@
-;; Test that the --initial-table flag works as expected
+;; Test that the --initial-table flag works as expected.
 
 ;; RUN: wasm-split %s --instrument --initial-table=1234 -S | filecheck %s
 
 ;; RUN: wasm-split %s -g -o1 %t.1.wasm -o2 %t.2.wasm --initial-table=1234
 ;; RUN: wasm-dis %t.1.wasm | filecheck %s
-;; RUN: wasm-dis %t.2.wasm | filecheck %s
 
 ;; CHECK: (table $table 1234 funcref)