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[Qemu-devel] [PATCH] tcp/mips: Change TCG_AREG0 (fp -> s0)
From: |
Stefan Weil |
Subject: |
[Qemu-devel] [PATCH] tcp/mips: Change TCG_AREG0 (fp -> s0) |
Date: |
Fri, 9 Apr 2010 09:36:25 +0200 |
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 was 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.
Cc: Aurelien Jarno <address@hidden>
Signed-off-by: Stefan Weil <address@hidden>
---
dyngen-exec.h | 2 +-
tcg/mips/tcg-target.c | 6 ++++--
tcg/mips/tcg-target.h | 2 +-
3 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/dyngen-exec.h b/dyngen-exec.h
index b9f6969..85a2616 100644
--- a/dyngen-exec.h
+++ b/dyngen-exec.h
@@ -61,7 +61,7 @@ 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..c9094ee 100644
--- a/tcg/mips/tcg-target.c
+++ b/tcg/mips/tcg-target.c
@@ -1450,7 +1450,9 @@ 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 +1461,7 @@ 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 */
};
@@ -1524,6 +1525,7 @@ void tcg_target_init(TCGContext *s)
tcg_regset_set_reg(s->reserved_regs, TCG_REG_AT); /* internal use */
tcg_regset_set_reg(s->reserved_regs, TCG_REG_T0); /* internal use */
tcg_regset_set_reg(s->reserved_regs, TCG_REG_RA); /* return address */
+ tcg_regset_set_reg(s->reserved_regs, TCG_REG_FP); /* frame pointer */
tcg_regset_set_reg(s->reserved_regs, TCG_REG_SP); /* stack pointer */
tcg_add_target_add_op_defs(mips_op_defs);
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