[Qemu-devel] [PATCH] target-arm: Set carry flag correctly for Thumb2 ORNS

[Peter Maydell]

The code for Thumb2 ORNS (or negated and set flags) was trashing
a TCG input register which was needed later for use in calculating
flags, with the effect that the carry flag was always set with
the wrong sense. Fix this by using a TCG temporary instead.

Signed-off-by: Peter Maydell <address@hidden>
---
 target-arm/translate.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/target-arm/translate.c b/target-arm/translate.c
index dbd958b..8f4e16b 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -7326,10 +7326,17 @@ gen_thumb2_data_op(DisasContext *s, int op, int conds, 
uint32_t shifter_out, TCG
         logic_cc = conds;
         break;
     case 3: /* orn */
-        tcg_gen_not_i32(t1, t1);
-        tcg_gen_or_i32(t0, t0, t1);
+    {
+        /* We can't just invert t1 in place because we might need it
+         * to calculate the carry flag later.
+         */
+        TCGv tmp = tcg_temp_new_i32();
+        tcg_gen_not_i32(tmp, t1);
+        tcg_gen_or_i32(t0, t0, tmp);
+        tcg_temp_free_i32(tmp);
         logic_cc = conds;
         break;
+    }
     case 4: /* eor */
         tcg_gen_xor_i32(t0, t0, t1);
         logic_cc = conds;
-- 
1.7.1