Register fp (frame pointer) is a bad choice for compilations
without optimisation, because the compiler makes heavy use
of this register (so the resulting code crashes).
Register s0 had been used for TCG_AREG1 in earlier releases,
but was no longer used and is now free for TCG_AREG0.
The resulting code works for compilations without
optimisation (tested with qemu mips in qemu mips
on x86 host).
v2:
* Remove s0 from tcg_target_callee_save_regs and add fp there.
Hint from Aurelien Jarno, thanks.
* Add fp to list of reserved registers.
v3:
* Don't add fp to list of reserved registers
Thanks to Richard Henderson.
* Remove s0 from tcg_target_reg_alloc_order.
Cc: Aurelien Jarno <aurel...@aurel32.net>
Cc: Richard Henderson <r...@twiddle.net>
Signed-off-by: Stefan Weil <w...@mail.berlios.de>
---
dyngen-exec.h | 2 +-
tcg/mips/tcg-target.c | 7 +++++--
tcg/mips/tcg-target.h | 2 +-
3 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/dyngen-exec.h b/dyngen-exec.h
index d04eda8..0700a2d 100644
--- a/dyngen-exec.h
+++ b/dyngen-exec.h
@@ -59,7 +59,7 @@ extern int printf(const char *, ...);
#elif defined(__hppa__)
#define AREG0 "r17"
#elif defined(__mips__)
-#define AREG0 "fp"
+#define AREG0 "s0"
#elif defined(__sparc__)
#ifdef CONFIG_SOLARIS
#define AREG0 "g2"
diff --git a/tcg/mips/tcg-target.c b/tcg/mips/tcg-target.c
index f4fb615..31296fc 100644
--- a/tcg/mips/tcg-target.c
+++ b/tcg/mips/tcg-target.c
@@ -69,7 +69,9 @@ static const char * const
tcg_target_reg_names[TCG_TARGET_NB_REGS] = {
/* check if we really need so many registers :P */
static const int tcg_target_reg_alloc_order[] = {
+#if 0 /* used for the global env (TCG_AREG0), so don't use it here */
TCG_REG_S0,
+#endif
TCG_REG_S1,
TCG_REG_S2,
TCG_REG_S3,
@@ -1450,7 +1452,9 @@ static const TCGTargetOpDef mips_op_defs[] = {
};
static int tcg_target_callee_save_regs[] = {
+#if 0 /* used for the global env (TCG_AREG0), so no need to save */
TCG_REG_S0,
+#endif
TCG_REG_S1,
TCG_REG_S2,
TCG_REG_S3,
@@ -1459,8 +1463,7 @@ static int tcg_target_callee_save_regs[] = {
TCG_REG_S6,
TCG_REG_S7,
TCG_REG_GP,
- /* TCG_REG_FP, */ /* currently used for the global env, so np
- need to save */
+ TCG_REG_FP,
TCG_REG_RA, /* should be last for ABI compliance */
};
diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index 0292d33..0028bfa 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -97,7 +97,7 @@ enum {
#undef TCG_TARGET_HAS_ext16u_i32 /* andi rt, rs, 0xffff */
/* Note: must be synced with dyngen-exec.h */
-#define TCG_AREG0 TCG_REG_FP
+#define TCG_AREG0 TCG_REG_S0
/* guest base is supported */
#define TCG_TARGET_HAS_GUEST_BASE
--
1.7.0
