[PATCH v2 10/12] tools/nolibc: loongarch/crt.h: shrink _start with _start_c

[Zhangjin Wu]

move most of the _start operations to _start_c().

Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
 tools/include/nolibc/loongarch/crt.h | 39 +++-------------------------
 1 file changed, 4 insertions(+), 35 deletions(-)

diff --git a/tools/include/nolibc/loongarch/crt.h b/tools/include/nolibc/loongarch/crt.h
index 253d2fccea1e..00bfc36b0747 100644
--- a/tools/include/nolibc/loongarch/crt.h
+++ b/tools/include/nolibc/loongarch/crt.h
@@ -8,22 +8,8 @@
 #define _NOLIBC_LOONGARCH_CRT_H
 
 #if __loongarch_grlen == 32
-#define LONGLOG      "2"
-#define SZREG        "4"
-#define REG_L        "ld.w"
-#define LONG_S       "st.w"
-#define LONG_ADD     "add.w"
-#define LONG_ADDI    "addi.w"
-#define LONG_SLL     "slli.w"
 #define LONG_BSTRINS "bstrins.w"
 #else /* __loongarch_grlen == 64 */
-#define LONGLOG      "3"
-#define SZREG        "8"
-#define REG_L        "ld.d"
-#define LONG_S       "st.d"
-#define LONG_ADD     "add.d"
-#define LONG_ADDI    "addi.d"
-#define LONG_SLL     "slli.d"
 #define LONG_BSTRINS "bstrins.d"
 #endif
 
@@ -32,28 +18,11 @@ void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_
 {
 	__asm__ volatile (
 #ifdef _NOLIBC_STACKPROTECTOR
-		"bl __stack_chk_init\n"               /* initialize stack protector                          */
+		"bl __stack_chk_init\n"            /* initialize stack protector                     */
 #endif
-		REG_L        " $a0, $sp, 0\n"         /* argc (a0) was in the stack                          */
-		LONG_ADDI    " $a1, $sp, "SZREG"\n"   /* argv (a1) = sp + SZREG                              */
-		LONG_SLL     " $a2, $a0, "LONGLOG"\n" /* envp (a2) = SZREG*argc ...                          */
-		LONG_ADDI    " $a2, $a2, "SZREG"\n"   /*             + SZREG (skip null)                     */
-		LONG_ADD     " $a2, $a2, $a1\n"       /*             + argv                                  */
-
-		"move          $a3, $a2\n"            /* iterate a3 over envp to find auxv (after NULL)      */
-		"0:\n"                                /* do {                                                */
-		REG_L        " $a4, $a3, 0\n"         /*   a4 = *a3;                                         */
-		LONG_ADDI    " $a3, $a3, "SZREG"\n"   /*   a3 += sizeof(void*);                              */
-		"bne           $a4, $zero, 0b\n"      /* } while (a4);                                       */
-		"la.pcrel      $a4, _auxv\n"          /* a4 = &_auxv                                         */
-		LONG_S       " $a3, $a4, 0\n"         /* store a3 into _auxv                                 */
-
-		"la.pcrel      $a3, environ\n"        /* a3 = &environ                                       */
-		LONG_S       " $a2, $a3, 0\n"         /* store envp(a2) into environ                         */
-		LONG_BSTRINS " $sp, $zero, 3, 0\n"    /* sp must be 16-byte aligned                          */
-		"bl            main\n"                /* main() returns the status code, we'll exit with it. */
-		"li.w          $a7, 93\n"             /* NR_exit == 93                                       */
-		"syscall       0\n"
+		"move          $a0, $sp\n"         /* save stack pointer to $a0, as arg1 of _start_c */
+		LONG_BSTRINS " $sp, $zero, 3, 0\n" /* $sp must be 16-byte aligned                    */
+		"bl            _start_c\n"         /* transfer to c runtime                          */
 	);
 	__builtin_unreachable();
 }
-- 
2.25.1