+/* ----------------------------------------------------------------------------
+ x86-64 is almost the same as plain x86.
+
+ I've done it using entirely inline assembler, because I couldn't
+ get gcc to generate the correct subtraction from %rsp by using
+ the local array variable trick. It didn't seem to reserve
+ enough space. Oh well, it's not much harder this way.
+
+ ------------------------------------------------------------------------- */
+
+#ifdef x86_64_TARGET_ARCH
+
+extern StgThreadReturnCode StgRun(StgFunPtr f, StgRegTable *basereg);
+
+static void StgRunIsImplementedInAssembler(void)
+{
+ __asm__ volatile (
+ /*
+ * save callee-saves registers on behalf of the STG code.
+ */
+ ".globl StgRun\n"
+ "StgRun:\n\t"
+ "subq %0, %%rsp\n\t"
+ "movq %%rsp, %%rax\n\t"
+ "addq %0-48, %%rax\n\t"
+ "movq %%rbx,0(%%rax)\n\t"
+ "movq %%rbp,8(%%rax)\n\t"
+ "movq %%r12,16(%%rax)\n\t"
+ "movq %%r13,24(%%rax)\n\t"
+ "movq %%r14,32(%%rax)\n\t"
+ "movq %%r15,40(%%rax)\n\t"
+ /*
+ * Set BaseReg
+ */
+ "movq %%rsi,%%rbx\n\t"
+ /*
+ * grab the function argument from the stack, and jump to it.
+ */
+ "movq %%rdi,%%rax\n\t"
+ "jmp *%%rax\n\t"
+
+ ".global " STG_RETURN "\n"
+ STG_RETURN ":\n\t"
+
+ "movq %%r13, %%rax\n\t" /* Return value in R1 */
+
+ /*
+ * restore callee-saves registers. (Don't stomp on %%rax!)
+ */
+ "movq %%rsp, %%rdx\n\t"
+ "addq %0-48, %%rdx\n\t"
+ "movq 0(%%rdx),%%rbx\n\t" /* restore the registers saved above */
+ "movq 8(%%rdx),%%rbp\n\t"
+ "movq 16(%%rdx),%%r12\n\t"
+ "movq 24(%%rdx),%%r13\n\t"
+ "movq 32(%%rdx),%%r14\n\t"
+ "movq 40(%%rdx),%%r15\n\t"
+ "addq %0, %%rsp\n\t"
+ "retq"
+
+ : : "i"(RESERVED_C_STACK_BYTES+48 /*stack frame size*/));
+}
+
+#endif /* x86-64 */
+