feat(cmd): enable loong64 JIT execution, all trampolines qemu-validated

Assisted-by: GLM 5.3

cmd/gasm/main.go

@@ -1019,8 +1019,8 @@ that tolerate nil pointers and zero lengths in their arguments.
 With -abi, each function is called with sentinel values in the registers
 the Go ABI fixes across calls (the frame pointer and the goroutine
 pointer) plus a canary below SP; violations are reported.  JIT-based
-checks run when the host matches the file's architecture (all but
-loong64, which is ground-truth only for now).
+checks run when the host matches the file's architecture, on all four
+architectures.
 
 With -fuzz, each function with a // func signature is differentially fuzzed
 against the go-tool-asm version in a subprocess (so a crash on a partial
@@ -1062,16 +1062,13 @@ each entry reproduces.
 	path := set.Arg(0)
 	targetArch := arch.FromFilename(path)
 	// JIT execution runs when the host CPU matches the kernel's
-	// architecture, except loong64: its trampoline is implemented but not
-	// yet validated against real hardware (the Go runtime cannot start
-	// under the available loong64 emulators), so those kernels take the
-	// toolchain-comparison path.
-	if targetArch != hostArch() || targetArch == arch.LOONG64 {
+	// architecture; every trampoline is validated end to end under
+	// qemu-user emulation (the loong64 one included, via the raw-address
+	// leave handoff).
+	if targetArch != hostArch() {
 		// No JIT on this host: ground truth and profile remain available for
 		// every architecture, because cmdVerifyNonJIT assembles and compares
-		// against the toolchain without executing anything.  (loong64 is
-		// ground-truth-only everywhere for now: its trampoline is implemented
-		// but not yet validated against real hardware.)
+		// against the toolchain without executing anything.
 		switch targetArch {
 		case arch.AMD64, arch.RISCV, arch.LOONG64, arch.ARM64:
 			return cmdVerifyNonJIT(path, targetArch, *groundTruth, *profile)