ST: Refine OSX asm.

trunk/3rdparty/st-srs/md_darwin.S

@@ -11,17 +11,17 @@
      */
     #define JB_RBX  0
     #define JB_RBP  1
-    #define JB_R12  2                   /* Backup IP, https://www.cnblogs.com/Five100Miles/p/8458561.html */
-    #define JB_R13  3                   /* Backup SP, https://www.cnblogs.com/Five100Miles/p/8458561.html */
-    #define JB_R14  4                   /* Backup LR, https://www.cnblogs.com/Five100Miles/p/8458561.html */
-    #define JB_R15  5                   /* Backup PC, https://www.cnblogs.com/Five100Miles/p/8458561.html */
+    #define JB_R12  2                   /* The first six integer or pointer arguments are passed in registers RDI, RSI, RDX, RCX, R8, R9. */
+    #define JB_R13  3                   /* If the callee wishes to use registers RBX, RSP, RBP, and R12–R15, it must restore their original values before returning control to the caller. */
+    #define JB_R14  4                   /* @see https://en.wikipedia.org/wiki/X86_calling_conventions */
+    #define JB_R15  5                   /* @see https://www.cnblogs.com/Five100Miles/p/8458561.html */
     #define JB_RSP  6
     #define JB_PC   7
 
     .file "md_darwin.S"
     .text
 
-    /* _st_md_cxt_save(__jmp_buf env) */ /* The env is rdi, http://blog.chinaunix.net/uid-20157960-id-1974354.html */
+    /* _st_md_cxt_save(__jmp_buf env) */ /* The env is rdi, https://en.wikipedia.org/wiki/X86_calling_conventions */
     .globl __st_md_cxt_save
         .align 16
     __st_md_cxt_save:
@@ -35,18 +35,18 @@
         movq %r14, (JB_R14*8)(%rdi)     /* Save r14 to env[4], *(int64_t*)(rdi+4)=r14 */
         movq %r15, (JB_R15*8)(%rdi)     /* Save r15 to env[5], *(int64_t*)(rdi+5)=r15 */
         /* Save SP */
-        leaq 8(%rsp), %rdx              /* Save *(int64_t*)(rsp+8) to rdx, https://my.oschina.net/guonaihong/blog/508907 */
-        movq %rdx, (JB_RSP*8)(%rdi)     /* Save rdx(rsp) to env[6], *(int64_t*)(rdi+6)=rdx */
+        leaq 8(%rsp), %r8              /* Save *(int64_t*)(rsp+8) to r8, https://github.com/ossrs/state-threads/issues/11#issuecomment-888709759 */
+        movq %r8, (JB_RSP*8)(%rdi)     /* Save r8(rsp) to env[6], *(int64_t*)(rdi+6)=r8 */
         /* Save PC we are returning to */
-        movq (%rsp), %rax               /* Save PC(parent function address) %(rsp) to rax */
-        movq %rax, (JB_PC*8)(%rdi)      /* Save rax(PC) to env[7], *(int64_t*)(rdi+7)=rax */
+        movq (%rsp), %r9               /* Save PC(parent function address) %(rsp) to r9 */
+        movq %r9, (JB_PC*8)(%rdi)      /* Save r9(PC) to env[7], *(int64_t*)(rdi+7)=r9 */
         xorq %rax, %rax                 /* Reset rax to 0 */
         ret
 
 
     /****************************************************************/
 
-    /* _st_md_cxt_restore(__jmp_buf env, int val) */ /* The env is rdi, val is esi/rsi, http://blog.chinaunix.net/uid-20157960-id-1974354.html */
+    /* _st_md_cxt_restore(__jmp_buf env, int val) */ /* The env is rdi, val is esi/rsi, https://en.wikipedia.org/wiki/X86_calling_conventions */
     .globl __st_md_cxt_restore
         .align 16
     __st_md_cxt_restore:
@@ -64,10 +64,11 @@
         mov $01, %eax                   /*          val=1;          */
         cmove %eax, %esi                /*      }                   */
         mov %esi, %eax                  /*      return val;         */
-        movq (JB_PC*8)(%rdi), %rdx      /* Load rdx(PC) from env[7] */
+        /* Restore PC and RSP */
+        movq (JB_PC*8)(%rdi), %r8      /* Load r8(PC) from env[7] */
         movq (JB_RSP*8)(%rdi), %rsp     /* Load rsp from env[6] */
         /* Jump to saved PC */
-        jmpq *%rdx                      /* Jump to rdx(PC) */
+        jmpq *%r8                      /* Jump to r8(PC) */
 
     /****************************************************************/