[wasm][test] Fix empty function bodies

Currently, the empty function bodies actually contain the byte 0, which
is the unreachable opcode. This CL fixes this to be empty function
bodies, and uses the macros more consistently.

This is the sixth CL in a series to improve our module decoder tests and
make them more readable.

R=titzer@chromium.org

Bug: v8:8238
Change-Id: I5f029210b4589797ee194e4082afec2c7bc31561
Reviewed-on: https://chromium-review.googlesource.com/c/1286343Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56736}

test/unittests/wasm/module-decoder-unittest.cc

@@ -88,16 +88,10 @@ struct CheckLEB1 : std::integral_constant<size_t, num> {
 #define FOUR_EMPTY_FUNCTIONS(sig_index) \
   SECTION(Function, ENTRY_COUNT(4), X4(sig_index))
 
-#define ONE_EMPTY_BODY SECTION(Code, ENTRY_COUNT(1), X1(ADD_COUNT(EMPTY_BODY)))
-
-#define TWO_EMPTY_BODIES \
-  SECTION(Code, ENTRY_COUNT(2), X2(ADD_COUNT(EMPTY_BODY)))
-
-#define THREE_EMPTY_BODIES \
-  SECTION(Code, ENTRY_COUNT(3), X3(ADD_COUNT(EMPTY_BODY)))
-
-#define FOUR_EMPTY_BODIES \
-  SECTION(Code, ENTRY_COUNT(4), X4(ADD_COUNT(EMPTY_BODY)))
+#define ONE_EMPTY_BODY SECTION(Code, ENTRY_COUNT(1), X1(EMPTY_BODY))
+#define TWO_EMPTY_BODIES SECTION(Code, ENTRY_COUNT(2), X2(EMPTY_BODY))
+#define THREE_EMPTY_BODIES SECTION(Code, ENTRY_COUNT(3), X3(EMPTY_BODY))
+#define FOUR_EMPTY_BODIES SECTION(Code, ENTRY_COUNT(4), X4(EMPTY_BODY))
 
 #define SIGNATURES_SECTION_VOID_VOID \
   SECTION(Type, ENTRY_COUNT(1), SIG_ENTRY_v_v)
@@ -1917,9 +1911,9 @@ TEST_F(WasmModuleVerifyTest, FunctionBodies_empty) {
 
 TEST_F(WasmModuleVerifyTest, FunctionBodies_one_empty) {
   static const byte data[] = {
-      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),      // --
-      FUNCTION_SIGNATURES_SECTION(1, 0),         // --
-      SECTION(Code, ENTRY_COUNT(1), EMPTY_BODY)  // --
+      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),  // --
+      FUNCTION_SIGNATURES_SECTION(1, 0),     // --
+      ONE_EMPTY_BODY                         // --
   };
   EXPECT_VERIFIES(data);
 }
@@ -1935,9 +1929,9 @@ TEST_F(WasmModuleVerifyTest, FunctionBodies_one_nop) {
 
 TEST_F(WasmModuleVerifyTest, FunctionBodies_count_mismatch1) {
   static const byte data[] = {
-      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),      // --
-      FUNCTION_SIGNATURES_SECTION(2, 0, 0),      // --
-      SECTION(Code, ENTRY_COUNT(1), EMPTY_BODY)  // --
+      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),  // --
+      FUNCTION_SIGNATURES_SECTION(2, 0, 0),  // --
+      ONE_EMPTY_BODY                         // --
   };
   EXPECT_FAILURE(data);
 }
@@ -1964,7 +1958,7 @@ TEST_F(WasmModuleVerifyTest, Names_one_empty) {
   static const byte data[] = {
       SIGNATURES_SECTION(1, SIG_ENTRY_v_v),                      // --
       FUNCTION_SIGNATURES_SECTION(1, 0),                         // --
-      SECTION(Code, ENTRY_COUNT(1), EMPTY_BODY),                 // --
+      ONE_EMPTY_BODY,                                            // --
       SECTION_NAMES(ENTRY_COUNT(1), FOO_STRING, NO_LOCAL_NAMES)  // --
   };
   EXPECT_VERIFIES(data);
@@ -1974,12 +1968,12 @@ TEST_F(WasmModuleVerifyTest, Names_two_empty) {
   // TODO(wasm): This test does not test anything (corrupt name section does not
   // fail validation).
   static const byte data[] = {
-      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),                   // --
-      FUNCTION_SIGNATURES_SECTION(2, 0, 0),                   // --
-      SECTION(Code, ENTRY_COUNT(2), EMPTY_BODY, EMPTY_BODY),  // --
-      SECTION_NAMES(ENTRY_COUNT(2),                           // --
-                    FOO_STRING, NO_LOCAL_NAMES,               // --
-                    FOO_STRING, NO_LOCAL_NAMES),              // --
+      SIGNATURES_SECTION(1, SIG_ENTRY_v_v),       // --
+      FUNCTION_SIGNATURES_SECTION(2, 0, 0),       // --
+      TWO_EMPTY_BODIES,                           // --
+      SECTION_NAMES(ENTRY_COUNT(2),               // --
+                    FOO_STRING, NO_LOCAL_NAMES,   // --
+                    FOO_STRING, NO_LOCAL_NAMES),  // --
   };
   EXPECT_VERIFIES(data);
 }