[Qemu-devel] [PATCH 17/40] target-arm: Share all common TCG temporaries

[Michael Roth <mdroth@linux.vnet.ibm.com>]

From: Richard Henderson <rth@twiddle.net>

This is a bug fix for aarch64.  At present, we have branches using
the 32-bit (translate.c) versions of cpu_[NZCV]F, but we set the flags
using the 64-bit (translate-a64.c) versions of cpu_[NZCV]F.  From
the view of the TCG code generator, these are unrelated variables.

The bug is hard to see because we currently only read these variables
from branches, and upon reaching a branch TCG will first spill live
variables and then reload the arguments of the branch.  Since the
32-bit versions were never live until reaching the branch, we'd re-read
the data that had just been spilled from the 64-bit versions.

There is currently no such problem with the cpu_exclusive_* variables,
but there's no point in tempting fate.

Cc: qemu-stable@nongnu.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-id: 1441909103-24666-2-git-send-email-rth@twiddle.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit 78bcaa3e37afbd0c5316634f917c13487384b6ca)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 target-arm/translate-a64.c | 22 ----------------------
 target-arm/translate.c     | 10 +++++-----
 target-arm/translate.h     |  8 ++++++++
 3 files changed, 13 insertions(+), 27 deletions(-)

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 689f2be..0f923d3 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -39,16 +39,9 @@
 
 static TCGv_i64 cpu_X[32];
 static TCGv_i64 cpu_pc;
-static TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;
 
 /* Load/store exclusive handling */
-static TCGv_i64 cpu_exclusive_addr;
-static TCGv_i64 cpu_exclusive_val;
 static TCGv_i64 cpu_exclusive_high;
-#ifdef CONFIG_USER_ONLY
-static TCGv_i64 cpu_exclusive_test;
-static TCGv_i32 cpu_exclusive_info;
-#endif
 
 static const char *regnames[] = {
     "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
@@ -104,23 +97,8 @@ void a64_translate_init(void)
                                           regnames[i]);
     }
 
-    cpu_NF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, NF), "NF");
-    cpu_ZF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, ZF), "ZF");
-    cpu_CF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, CF), "CF");
-    cpu_VF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, VF), "VF");
-
-    cpu_exclusive_addr = tcg_global_mem_new_i64(TCG_AREG0,
-        offsetof(CPUARMState, exclusive_addr), "exclusive_addr");
-    cpu_exclusive_val = tcg_global_mem_new_i64(TCG_AREG0,
-        offsetof(CPUARMState, exclusive_val), "exclusive_val");
     cpu_exclusive_high = tcg_global_mem_new_i64(TCG_AREG0,
         offsetof(CPUARMState, exclusive_high), "exclusive_high");
-#ifdef CONFIG_USER_ONLY
-    cpu_exclusive_test = tcg_global_mem_new_i64(TCG_AREG0,
-        offsetof(CPUARMState, exclusive_test), "exclusive_test");
-    cpu_exclusive_info = tcg_global_mem_new_i32(TCG_AREG0,
-        offsetof(CPUARMState, exclusive_info), "exclusive_info");
-#endif
 }
 
 static inline ARMMMUIdx get_a64_user_mem_index(DisasContext *s)
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 69ac18c..4385322 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -64,12 +64,12 @@ TCGv_ptr cpu_env;
 /* We reuse the same 64-bit temporaries for efficiency.  */
 static TCGv_i64 cpu_V0, cpu_V1, cpu_M0;
 static TCGv_i32 cpu_R[16];
-static TCGv_i32 cpu_CF, cpu_NF, cpu_VF, cpu_ZF;
-static TCGv_i64 cpu_exclusive_addr;
-static TCGv_i64 cpu_exclusive_val;
+TCGv_i32 cpu_CF, cpu_NF, cpu_VF, cpu_ZF;
+TCGv_i64 cpu_exclusive_addr;
+TCGv_i64 cpu_exclusive_val;
 #ifdef CONFIG_USER_ONLY
-static TCGv_i64 cpu_exclusive_test;
-static TCGv_i32 cpu_exclusive_info;
+TCGv_i64 cpu_exclusive_test;
+TCGv_i32 cpu_exclusive_info;
 #endif
 
 /* FIXME:  These should be removed.  */
diff --git a/target-arm/translate.h b/target-arm/translate.h
index 9ab978f..679bdbc 100644
--- a/target-arm/translate.h
+++ b/target-arm/translate.h
@@ -62,7 +62,15 @@ typedef struct DisasContext {
     TCGv_i64 tmp_a64[TMP_A64_MAX];
 } DisasContext;
 
+/* Share the TCG temporaries common between 32 and 64 bit modes.  */
 extern TCGv_ptr cpu_env;
+extern TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;
+extern TCGv_i64 cpu_exclusive_addr;
+extern TCGv_i64 cpu_exclusive_val;
+#ifdef CONFIG_USER_ONLY
+extern TCGv_i64 cpu_exclusive_test;
+extern TCGv_i32 cpu_exclusive_info;
+#endif
 
 static inline int arm_dc_feature(DisasContext *dc, int feature)
 {
-- 
1.9.1