Emit and use adhoc function descriptor for code_gen_prologue on PPC64

Thus avoiding fragile inline assembly hackery to call into generated
code.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4939 c046a42c-6fe2-441c-8c8c-71466251a162

tcg/ppc64/tcg-target.c

@@ -773,6 +773,7 @@ static void tcg_out_qemu_st (TCGContext *s, const TCGArg *args, int opc)
 void tcg_target_qemu_prologue (TCGContext *s)
 {
     int i, frame_size;
+    uint64_t addr;
 
     frame_size = 0
         + 8                     /* back chain */
@@ -786,6 +787,12 @@ void tcg_target_qemu_prologue (TCGContext *s)
         ;
     frame_size = (frame_size + 15) & ~15;
 
+    /* First emit adhoc function descriptor */
+    addr = (uint64_t) s->code_ptr + 24;
+    tcg_out32 (s, addr >> 32); tcg_out32 (s, addr); /* entry point */
+    s->code_ptr += 16;          /* skip TOC and environment pointer */
+
+    /* Prologue */
     tcg_out32 (s, MFSPR | RT (0) | LR);
     tcg_out32 (s, STDU | RS (1) | RA (1) | (-frame_size & 0xffff));
     for (i = 0; i < ARRAY_SIZE (tcg_target_callee_save_regs); ++i)
@@ -796,10 +803,11 @@ void tcg_target_qemu_prologue (TCGContext *s)
                        )
             );
     tcg_out32 (s, STD | RS (0) | RA (1) | (frame_size + 20));
-    tcg_out32 (s, STD | RS (2) | RA (1) | (frame_size + 40));
 
     tcg_out32 (s, MTSPR | RS (3) | CTR);
     tcg_out32 (s, BCCTR | BO_ALWAYS);
+
+    /* Epilogue */
     tb_ret_addr = s->code_ptr;
 
     for (i = 0; i < ARRAY_SIZE (tcg_target_callee_save_regs); ++i)
@@ -810,7 +818,6 @@ void tcg_target_qemu_prologue (TCGContext *s)
                        )
             );
     tcg_out32 (s, LD | RT (0) | RA (1) | (frame_size + 20));
-    tcg_out32 (s, LD | RT (2) | RA (1) | (frame_size + 40));
     tcg_out32 (s, MTSPR | RS (0) | LR);
     tcg_out32 (s, ADDI | RT (1) | RA (1) | frame_size);
     tcg_out32 (s, BCLR | BO_ALWAYS);

tcg/tcg.h

@@ -413,24 +413,9 @@ uint64_t tcg_helper_divu_i64(uint64_t arg1, uint64_t arg2);
 uint64_t tcg_helper_remu_i64(uint64_t arg1, uint64_t arg2);
 
 extern uint8_t code_gen_prologue[];
-#ifdef __powerpc__
-#ifdef __powerpc64__
-#define tcg_qemu_tb_exec(tb_ptr)                                        \
-    ({ unsigned long p;                                                 \
-       asm volatile (                                                   \
-         "mtctr %1\n\t"                                                 \
-         "mr 3,%2\n\t"                                                  \
-         "bctrl\n\t"                                                    \
-         "mr %0,3\n\t"                                                  \
-         : "=r" (p)                                                     \
-         : "r" (code_gen_prologue), "r" (tb_ptr)                        \
-         : "3", "4", "5", "6", "7", "8", "9", "10", "11", "12");        \
-    p;                                                                  \
-    })
-#else
+#if defined(__powerpc__) && !defined(__powerpc64__)
 #define tcg_qemu_tb_exec(tb_ptr) \
     ((long REGPARM __attribute__ ((longcall)) (*)(void *))code_gen_prologue)(tb_ptr)
-#endif
 #else
 #define tcg_qemu_tb_exec(tb_ptr) ((long REGPARM (*)(void *))code_gen_prologue)(tb_ptr)
 #endif