tcg-hppa: Fix GUEST_BASE initialization in prologue.

Load from the guest_base variable rather than embed a constant.
Always reserve TCG_GUEST_BASE_REG if guest base support enabled.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

tcg/hppa/tcg-target.c

@@ -34,10 +34,6 @@ static const char * const tcg_target_reg_names[TCG_TARGET_NB_REGS] = {
 /* This is an 8 byte temp slot in the stack frame.  */
 #define STACK_TEMP_OFS -16
 
-#ifndef GUEST_BASE
-#define GUEST_BASE 0
-#endif
-
 #ifdef CONFIG_USE_GUEST_BASE
 #define TCG_GUEST_BASE_REG TCG_REG_R16
 #else
@@ -1649,9 +1645,13 @@ void tcg_target_qemu_prologue(TCGContext *s)
                    TCG_REG_SP, -frame_size + i * 4);
     }
 
-    if (GUEST_BASE != 0) {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_GUEST_BASE_REG, GUEST_BASE);
-    }
+#ifdef CONFIG_USE_GUEST_BASE
+    /* Note that GUEST_BASE can change after the prologue is generated.
+       To combat that, load the value from the variable instead of
+       embedding a constant here.  */
+    tcg_out_ld(s, TCG_TYPE_PTR, TCG_GUEST_BASE_REG,
+               TCG_REG_R0, (tcg_target_long)&guest_base);
+#endif
 
     /* Jump to TB, and adjust R18 to be the return address.  */
     tcg_out32(s, INSN_BLE_SR4 | INSN_R2(TCG_REG_R26));
@@ -1696,9 +1696,9 @@ void tcg_target_init(TCGContext *s)
     tcg_regset_set_reg(s->reserved_regs, TCG_REG_DP);  /* data pointer */
     tcg_regset_set_reg(s->reserved_regs, TCG_REG_SP);  /* stack pointer */
     tcg_regset_set_reg(s->reserved_regs, TCG_REG_R31); /* ble link reg */
-    if (GUEST_BASE != 0) {
-        tcg_regset_set_reg(s->reserved_regs, TCG_GUEST_BASE_REG);
-    }
+#ifdef CONFIG_USE_GUEST_BASE
+    tcg_regset_set_reg(s->reserved_regs, TCG_GUEST_BASE_REG);
+#endif
 
     tcg_add_target_add_op_defs(hppa_op_defs);
 }