[PATCH v2 26/27] target/s390x: Pass original r2 register to BCR

[Richard Henderson]

We do not modify any general-purpose registers in BCR,
which means that we may be able to avoid saving the
value across a branch.

Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/s390x/tcg/insn-data.h.inc |  2 +-
 target/s390x/tcg/translate.c     | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/target/s390x/tcg/insn-data.h.inc b/target/s390x/tcg/insn-data.h.inc
index 54d4250c9f..0e5a1062ae 100644
--- a/target/s390x/tcg/insn-data.h.inc
+++ b/target/s390x/tcg/insn-data.h.inc
@@ -121,7 +121,7 @@
 /* BRANCH INDIRECT ON CONDITION */
     C(0xe347, BIC,     RXY_b, MIE2,0, m2_64w, 0, 0, bc, 0)
 /* BRANCH ON CONDITION */
-    C(0x0700, BCR,     RR_b,  Z,   0, r2_nz, 0, 0, bc, 0)
+    C(0x0700, BCR,     RR_b,  Z,   0, r2_o_nz, 0, 0, bc, 0)
     C(0x4700, BC,      RX_b,  Z,   0, a2, 0, 0, bc, 0)
 /* BRANCH RELATIVE ON CONDITION */
     C(0xa704, BRC,     RI_c,  Z,   0, 0, 0, 0, bc, 0)
diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 268de1359b..7280498290 100644
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -5704,6 +5704,16 @@ static void in2_r2_nz(DisasContext *s, DisasOps *o)
 }
 #define SPEC_in2_r2_nz 0
 
+static void in2_r2_o_nz(DisasContext *s, DisasOps *o)
+{
+    int r2 = get_field(s, r2);
+    if (r2 != 0) {
+        o->in2 = regs[r2];
+        o->g_in2 = true;
+    }
+}
+#define SPEC_in2_r2_o_nz 0
+
 static void in2_r2_8s(DisasContext *s, DisasOps *o)
 {
     o->in2 = tcg_temp_new_i64();
-- 
2.34.1