[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

src/runtime/runtime-wasm.cc

Index: src/runtime/runtime-wasm.cc
diff --git a/src/runtime/runtime-wasm.cc b/src/runtime/runtime-wasm.cc
index e840eb464e9797325d5a89514ff82c3a94b3d3c0..161f7f4d52331fc0a371b20c14593ff773c84f41 100644
--- a/src/runtime/runtime-wasm.cc
+++ b/src/runtime/runtime-wasm.cc
@@ -15,6 +15,7 @@
 #include "src/v8memory.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-objects.h"
+#include "src/wasm/wasm-opcodes.h"
 
 namespace v8 {
 namespace internal {
@@ -61,14 +62,14 @@ RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
       wasm::GrowMemory(isolate, instance, delta_pages));
 }
 
-RUNTIME_FUNCTION(Runtime_ThrowWasmError) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(2, args.length());
-  CONVERT_SMI_ARG_CHECKED(message_id, 0);
-  CONVERT_SMI_ARG_CHECKED(byte_offset, 1);
+Object* ThrowRuntimeError(Isolate* isolate, int message_id, int byte_offset) {
   Handle<Object> error_obj = isolate->factory()->NewWasmRuntimeError(
       static_cast<MessageTemplate::Template>(message_id));
 
+  if (FLAG_wasm_trap_if) {
+    return isolate->Throw(*error_obj);
+  }
+
   // For wasm traps, the byte offset (a.k.a source position) can not be
   // determined from relocation info, since the explicit checks for traps
   // converge in one singe block which calls this runtime function.
@@ -115,6 +116,26 @@ RUNTIME_FUNCTION(Runtime_ThrowWasmError) {
   return isolate->Throw(*error_obj);
 }
 
+RUNTIME_FUNCTION(Runtime_ThrowWasmError) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(2, args.length());
+  CONVERT_SMI_ARG_CHECKED(message_id, 0);
+  CONVERT_SMI_ARG_CHECKED(byte_offset, 1);
+  return ThrowRuntimeError(isolate, message_id, byte_offset);
+}
+
+#define DECLARE_ENUM(name)                                                    \
+  RUNTIME_FUNCTION(Runtime_ThrowWasm##name) {                                 \

[titzer, 2016/12/12 14:21:34]

Can you factor the common code out of this macro into a helper function so that
we don't have N copies of it?

[ahaas, 2016/12/13 12:38:59]

Done.

+    HandleScope scope(isolate);                                               \
+    int message_id = wasm::WasmOpcodes::TrapReasonToMessageId(wasm::k##name); \
+    printf("Throw trap %s\n",                                                 \
+           wasm::WasmOpcodes::TrapReasonMessage(wasm::k##name));              \
+    int byte_offset = 1;                                                      \
+    return ThrowRuntimeError(isolate, message_id, byte_offset);               \
+  }
+FOREACH_WASM_TRAPREASON(DECLARE_ENUM)
+#undef DECLARE_ENUM
+
 RUNTIME_FUNCTION(Runtime_WasmThrowTypeError) {
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());