[Qemu-devel] [mttcg RFC v4 6/6] target-arm: Use a runtime helper for excl accesses

[Alvise Rigo <a.rigo@virtualopensystems.com>]

Instead of using TCG's load and store instructions, use a runtime helper
as a hook for the slow-path.

This is a proof of concept to verify that this approach is actually
working.
At the moment only the 32bit STREX is relying on this new code-path and
it's working as expected.

Signed-off-by: Alvise Rigo <a.rigo@virtualopensystems.com>
---
 target-arm/helper.h    |  2 ++
 target-arm/op_helper.c | 11 +++++++++++
 target-arm/translate.c | 12 +++++++++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/target-arm/helper.h b/target-arm/helper.h
index c77bf04..c4da74a 100644
--- a/target-arm/helper.h
+++ b/target-arm/helper.h
@@ -534,6 +534,8 @@ DEF_HELPER_4(atomic_cmpxchg64, i32, env, i32, i64, i32)
 DEF_HELPER_1(atomic_clear, void, env)
 DEF_HELPER_3(atomic_claim, void, env, i32, i64)
 
+DEF_HELPER_4(stcond_aa32_i32, i32, env, i32, i32, i32)
+
 #ifdef TARGET_AARCH64
 #include "helper-a64.h"
 #endif
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index ba8c5f5..53dcdde 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -1095,3 +1095,14 @@ uint32_t HELPER(ror_cc)(CPUARMState *env, uint32_t x, uint32_t i)
         return ((uint32_t)x >> shift) | (x << (32 - shift));
     }
 }
+
+uint32_t HELPER(stcond_aa32_i32)(CPUARMState *env, uint32_t val, uint32_t addr,
+                                                            uint32_t index)
+{
+    CPUArchState *state = env;
+    TCGMemOpIdx op;
+
+    op = make_memop_idx(MO_LEUL, index);
+
+    return helper_le_stcondl_mmu(state, addr, val, op, 0);
+}
diff --git a/target-arm/translate.c b/target-arm/translate.c
index d90a27b..591ce97 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -1006,6 +1006,17 @@ static inline void gen_aa32_stex64(TCGv_i32 is_dirty, TCGv_i64 val,
 
 #endif
 
+/* Use the runtime helper for 32bit exclusive stores. */
+static inline void gen_aa32_stex32(TCGv_i32 is_dirty, TCGv_i32 val,
+                                   TCGv_i32 addr, int index)
+{
+    TCGv index_tmp = tcg_temp_new_i32();
+
+    tcg_gen_movi_i32(index_tmp, index);
+    gen_helper_stcond_aa32_i32(is_dirty, cpu_env, val, addr, index_tmp);
+    tcg_temp_free_i32(index_tmp);
+}
+
 DO_GEN_LD(8s, MO_SB)
 DO_GEN_LD(8u, MO_UB)
 DO_GEN_LD(8uex, MO_UB | MO_EXCL)
@@ -1021,7 +1032,6 @@ DO_GEN_ST(32, MO_TEUL)
 /* Load/Store exclusive generators (always unsigned) */
 DO_GEN_STEX(8, MO_UB)
 DO_GEN_STEX(16, MO_TEUW)
-DO_GEN_STEX(32, MO_TEUL)
 
 static inline void gen_set_pc_im(DisasContext *s, target_ulong val)
 {
-- 
2.5.0