[Qemu-devel] [PATCH 2/7] target-ppc: Introduce gen_set_cr1_from_fpscr

[Tom Musta <tommusta@gmail.com>]

The Power ISA supports a mode in many floating point instructions whereby
the Condition Register field 1 (CR[1]) receives a copy of the Floating
Point Status (FPSCR) bits 32:35, also known as FX, FEX VX and OX.

The existing QEMU code is mostly wrong -- CR[1] is set to the Floating
Point Condition Code (FPSCR[FPCC]).  Furthermore, this code is buried
inside the code that generates the FPSCR[FPRF] code, which is awkward.

Introduce a new generator utility that correctly sets CR[1] from the
FPSCR bits.  Subsequent patches will correct various segments of
the defective code and will clean up the gen_compute_fprf()
utility.

Signed-off-by: Tom Musta <tommusta@gmail.com>
---
 target-ppc/translate.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index d03daea..7775bf4 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -249,6 +249,14 @@ static inline void gen_reset_fpstatus(void)
     gen_helper_reset_fpstatus(cpu_env);
 }
 
+static inline void gen_set_cr1_from_fpscr(void)
+{
+    TCGv_i32 t0 = tcg_temp_new_i32();
+    tcg_gen_trunc_tl_i32(t0, cpu_fpscr);
+    tcg_gen_shri_i32(cpu_crf[1], t0, 28);
+    tcg_temp_free_i32(t0);
+}
+
 static inline void gen_compute_fprf(TCGv_i64 arg, int set_fprf, int set_rc)
 {
     TCGv_i32 t0 = tcg_temp_new_i32();
-- 
1.7.1