[wasm] Introduce jiterpreter control flow pass (#83247)

* Checkpoint CFG

Generate fallthrough in CFG

Generate branch block header partially in cfg

Emit branches in CFG

Checkpoint: Emit loop and exit return in CFG (broken)

Fix CFG emitting function header in the wrong place

Improve accuracy of cfg size estimation

Remove log messages

Checkpoint: Forward branches partially working

Fix non-conditional branches not being added to target table
Remove fallthrough

* Implement backward branches via a dispatch table

* Cleanup

* Cleanup

* Remove use of DataView since it has a hazard around heap growth
Use copyWithin to implement appendBytes where possible
More accurate overhead calculation

src/mono/mono/mini/interp/jiterpreter.c

@@ -1281,6 +1281,31 @@ mono_jiterp_get_member_offset (int member) {
 	}
 }
 
+#define JITERP_NUMBER_MODE_U32 0
+#define JITERP_NUMBER_MODE_I32 1
+#define JITERP_NUMBER_MODE_F32 2
+#define JITERP_NUMBER_MODE_F64 3
+
+EMSCRIPTEN_KEEPALIVE void
+mono_jiterp_write_number_unaligned (void *dest, double value, int mode) {
+	switch (mode) {
+		case JITERP_NUMBER_MODE_U32:
+			*((uint32_t *)dest) = (uint32_t)value;
+			return;
+		case JITERP_NUMBER_MODE_I32:
+			*((int32_t *)dest) = (int32_t)value;
+			return;
+		case JITERP_NUMBER_MODE_F32:
+			*((float *)dest) = (float)value;
+			return;
+		case JITERP_NUMBER_MODE_F64:
+			*((double *)dest) = value;
+			return;
+		default:
+			g_assert_not_reached();
+	}
+}
+
 // HACK: fix C4206
 EMSCRIPTEN_KEEPALIVE
 #endif // HOST_BROWSER

src/mono/wasm/runtime/cwraps.ts

@@ -100,6 +100,7 @@ const fn_signatures: SigLine[] = [
     [false, "mono_jiterp_encode_leb52", "number", ["number", "number", "number"]],
     [false, "mono_jiterp_encode_leb64_ref", "number", ["number", "number", "number"]],
     [false, "mono_jiterp_encode_leb_signed_boundary", "number", ["number", "number", "number"]],
+    [false, "mono_jiterp_write_number_unaligned", "void", ["number", "number", "number"]],
     [true, "mono_jiterp_type_is_byref", "number", ["number"]],
     [true, "mono_jiterp_get_size_of_stackval", "number", []],
     [true, "mono_jiterp_parse_option", "number", ["string"]],
@@ -234,6 +235,7 @@ export interface t_Cwraps {
     mono_jiterp_debug_count(): number;
     mono_jiterp_get_trace_hit_count(traceIndex: number): number;
     mono_jiterp_get_polling_required_address(): Int32Ptr;
+    mono_jiterp_write_number_unaligned(destination: VoidPtr, value: number, mode: number): void;
 }
 
 const wrapped_c_functions: t_Cwraps = <any>{};