add copy and patch jit infrastructure with a stencil compilation pipeline

Author: friendlymatthew

Cargo.lock

@@ -1,5 +1,5 @@
 [workspace]
-members = ["gabagool", "gabagool-debug-adapter"]
+members = ["gabagool", "gabagool-debug-adapter", "gabagool-stencils"]
 default-members = ["gabagool"]
 resolver = "2"
 

Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "gabagool-stencils"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+
+[dependencies]

gabagool-stencils/Cargo.toml

@@ -0,0 +1,14 @@
+pub fn add(left: u64, right: u64) -> u64 {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}

gabagool-stencils/src/lib.rs

@@ -0,0 +1,36 @@
+
+#ifndef STENCIL_CONTEXT_H
+#define STENCIL_CONTEXT_H
+
+#include <stdint.h>
+
+typedef struct StencilContext StencilContext;
+
+// every stencil must be a funciton with this signature
+typedef void (*StencilFn)(StencilContext *ctx);
+
+typedef struct {
+  uint64_t imm0;
+  uint64_t imm1;
+} OpImmediate;
+
+// this is the entire execution state, passed to every stencil
+struct StencilContext {
+  uint64_t *stack;
+  uint64_t stack_pointer;
+  uint64_t *locals;
+  uint64_t *mem_base;
+  uint64_t mem_len;
+  uint64_t *globals;
+  const OpImmediate *imm_table;
+  const StencilFn *fn_table;
+  uint32_t pc;
+  uint8_t snapshot_flag;
+  uint8_t exit_reason;
+  uint32_t exit_value;
+};
+
+#define EXIT_SNAPSHOT 0
+#define EXIT_RETURN 1
+
+#endif

gabagool-stencils/src/stencil_context.h

@@ -0,0 +1,29 @@
+
+#include "stencil_context.h"
+
+void nop(StencilContext *ctx) {
+  ctx->pc += 1;
+
+  if (ctx->snapshot_flag) {
+    ctx->exit_reason = EXIT_SNAPSHOT;
+    return;
+  }
+
+  __attribute__((musttail)) return ctx->fn_table[ctx->pc](ctx);
+}
+
+void i32_const(StencilContext *ctx) {
+  ctx->stack[ctx->stack_pointer] = (uint32_t)ctx->imm_table[ctx->pc].imm0;
+
+  ctx->stack_pointer += 1;
+  ctx->pc += 1;
+
+  if (ctx->snapshot_flag) {
+    ctx->exit_reason = EXIT_SNAPSHOT;
+    return;
+  }
+
+  __attribute__((musttail)) return ctx->fn_table[ctx->pc](ctx);
+}
+
+void return_(StencilContext *ctx) { ctx->exit_reason = EXIT_RETURN; }

gabagool-stencils/src/stencils.c

@@ -10,11 +10,19 @@ license.workspace = true
 
 [dev-dependencies]
 insta = "1"
+wat = "1"
+
+[dependencies]
+libc = { version = "0.2.183", optional = true }
 
 [build-dependencies]
 wast = { version = "245.0.1", optional = true }
+cc = { version = "1.2.57", optional = true }
+object = { version = "0.38.1", optional = true }
+
 
 [features]
 core-tests = ["wast"]
 component-tests = []
 debugger = []
+jit = ["cc", "libc", "object"]