[wasm] Get rid of extra wrappers when import another wasm export

test/mjsunit/wasm/test-import-export-wrapper.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-wasm --allow-natives-syntax
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+var expect_elison = 0;
+var expect_no_elison = 1;
+// function calls stack: first_export -> first_func -> first_import ->
+// second_export -> second_import
+// In this case, first_import and second_export have same signature,
+// So that wrappers will be removed
+(function TestWasmWrapperElison() {
+    var second_module = new WasmModuleBuilder();
+    var sig_index = second_module.addType(kSig_v_i);
+    second_module.addImportWithModule("import_module_2", "import_name_2", sig_index);
+    second_module.addFunction("second_export", sig_index)
+                .addBody([
+                    kExprGetLocal, 0,
+                    kExprCallImport, kArity1, 0,
+                ])
+                .exportFunc();
+
+    var first_module = new WasmModuleBuilder();
+    var sig_index = first_module.addType(kSig_v_i);
+    first_module.addImportWithModule("import_module_1", "import_name_1", sig_index);
+    first_module.addFunction("first_export", sig_index)
+                .addBody([
+                    kExprGetLocal, 0,
+                    kExprCallFunction, kArity1, 1
+                ])
+                .exportFunc();
+    first_module.addFunction("first_func", sig_index)
+                .addBody([
+                    kExprI32Const, 1,
+                    kExprGetLocal, 0,
+                    kExprI32Add,
+                    kExprCallImport, kArity1, 0
+                ]);
+
+    var f = second_module.instantiate({import_module_2:{import_name_2:print}})
+        .exports.second_export;
+    var the_export = first_module.instantiate({import_module_1:{import_name_1:f}})

[Mircea Trofin, 2016/08/04 00:51:28]

don't you want to still call the_export, to make sure code is executed as
expected (same comment for below)

[Chen, 2016/08/04 17:21:53]

Done.

+        .exports.first_export;
+    %CheckWasmWrapperElison(the_export, expect_elison);
+})();
+
+// function calls stack: first_export -> first_func -> first_import ->
+// second_export -> second_import
+// In this case, second_export has less params than first_import,
+// So that wrappers will not be removed
+(function TestWasmWrapperNoElisonLessParams() {
+    var second_module = new WasmModuleBuilder();
+    var sig_index_1 = second_module.addType(kSig_v_i);
+    second_module.addImportWithModule("import_module_2", "import_name_2", sig_index_1);
+    second_module.addFunction("second_export", sig_index_1)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprCallImport, kArity1, 0
+        ])
+        .exportFunc();
+
+    var first_module = new WasmModuleBuilder();
+    var sig_index_2 = first_module.addType(kSig_v_ii);
+    first_module.addImportWithModule("import_module_1", "import_name_1", sig_index_2);
+    first_module.addFunction("first_export", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallFunction, kArity2, 1
+        ])
+        .exportFunc();
+    first_module.addFunction("first_func", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallImport, kArity2, 0
+        ]);
+
+    var f = second_module.instantiate({import_module_2:{import_name_2:print}})
+        .exports.second_export;
+    var the_export = first_module.instantiate({import_module_1:{import_name_1:f}})
+        .exports.first_export;
+    %CheckWasmWrapperElison(the_export, expect_no_elison);
+})();
+
+// function calls stack: first_export -> first_func -> first_import ->
+// second_export -> second_import
+// In this case, second_export has more params than first_import,
+// So that wrappers will not be removed
+(function TestWasmWrapperNoElisonMoreParams() {
+    var second_module = new WasmModuleBuilder();
+    var sig_index_3 = second_module.addType(kSig_v_iii);
+    second_module.addImportWithModule("import_module_2", "import_name_2", sig_index_3);
+    second_module.addFunction("second_export", sig_index_3)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprGetLocal, 2,
+            kExprCallImport, kArity3, 0
+        ])
+        .exportFunc();
+
+    var first_module = new WasmModuleBuilder();
+    var sig_index_2 = first_module.addType(kSig_v_ii);
+    first_module.addImportWithModule("import_module_1", "import_name_1", sig_index_2);
+    first_module.addFunction("first_export", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallFunction, kArity2, 1
+        ])
+        .exportFunc();
+    first_module.addFunction("first_func", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallImport, kArity2, 0
+        ]);
+
+    var f = second_module.instantiate({import_module_2:{import_name_2:print}})
+        .exports.second_export;
+    var the_export = first_module.instantiate({import_module_1:{import_name_1:f}})
+        .exports.first_export;
+    %CheckWasmWrapperElison(the_export, expect_no_elison);
+})();
+
+// function calls stack: first_export -> first_func -> first_import ->
+// second_export -> second_import
+// In this case, second_export has different params type with first_import,
+// So that wrappers will not be removed
+(function TestWasmWrapperNoElisonTypeMismatch() {
+    var second_module = new WasmModuleBuilder();
+    var sig_index_2 = second_module.addType(kSig_v_dd);
+    second_module.addImportWithModule("import_module_2", "import_name_2", sig_index_2);
+    second_module.addFunction("second_export", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallImport, kArity2, 0
+        ])
+        .exportFunc();
+
+    var first_module = new WasmModuleBuilder();
+    var sig_index_2 = first_module.addType(kSig_v_ii);
+    first_module.addImportWithModule("import_module_1", "import_name_1", sig_index_2);
+    first_module.addFunction("first_export", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallFunction, kArity2, 1
+        ])
+        .exportFunc();
+    first_module.addFunction("first_func", sig_index_2)
+        .addBody([
+            kExprGetLocal, 0,
+            kExprGetLocal, 1,
+            kExprCallImport, kArity2, 0
+        ]);
+
+    var f = second_module.instantiate({import_module_2:{import_name_2:print}})
+        .exports.second_export;
+    var the_export = first_module.instantiate({import_module_1:{import_name_1:f}})
+        .exports.first_export;
+    %CheckWasmWrapperElison(the_export, expect_no_elison);
+})();