feat(verify): add the JIT execution substrate and gasm verify subcommand

Assisted-by: Qwen 3.8 Max Preview
2026-08-02 23:11:30 +02:00
parent 5af12e15ac
commit c9775c2b95
11 changed files with 785 additions and 2 deletions
@@ -0,0 +1,30 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include "textflag.h"
+
+// ABI0 JIT trampoline.  enterJIT switches from the Go stack to a prepared
+// stack and jumps to the assembled function; when the function RETs, control
+// lands in leaveJIT, which restores the Go stack and returns to the Go caller.
+//
+// The prepared stack must begin with the address of leaveJIT (the return
+// address the JIT function will pop), followed by the function's ABI0
+// argument area.
+//
+// Single-threaded: savedSP is a package global, so only one JIT call may be
+// in flight at a time.  gasm verify runs sequentially.
+
+// func enterJIT(fn uintptr, stack uintptr)
+// Switches to the prepared stack and jumps to fn.  Does not return normally;
+// the JIT function's RET transfers control to leaveJIT.
+TEXT ·enterJIT(SB), NOSPLIT, $0-16
+	MOVQ fn+0(FP), AX      // target function address (before SP switch)
+	MOVQ SP, ·savedSP(SB)  // preserve the Go stack pointer
+	MOVQ stack+8(FP), SP   // switch to the prepared stack
+	JMP  AX
+
+// func leaveJIT()
+// Restores the Go stack pointer and returns to enterJIT's caller.
+TEXT ·leaveJIT(SB), NOSPLIT, $0-0
+	MOVQ ·savedSP(SB), SP
+	RET