[PATCH] target/arm: Use deposit_z() in BCF opcode

[Philippe Mathieu-Daudé]

When clearing a bitfield we don't need to lead the
source register. Use deposit_z_i32() with the BFC
opcode to save a load_reg() call.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 target/arm/tcg/translate.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/target/arm/tcg/translate.c b/target/arm/tcg/translate.c
index b71ac2d0d5..1a6938d1b3 100644
--- a/target/arm/tcg/translate.c
+++ b/target/arm/tcg/translate.c
@@ -7255,7 +7255,7 @@ static bool trans_UBFX(DisasContext *s, arg_UBFX *a)
 static bool trans_BFCI(DisasContext *s, arg_BFCI *a)
 {
     int msb = a->msb, lsb = a->lsb;
-    TCGv_i32 t_in, t_rd;
+    TCGv_i32 t_rd;
     int width;
 
     if (!ENABLE_ARCH_6T2) {
@@ -7268,15 +7268,14 @@ static bool trans_BFCI(DisasContext *s, arg_BFCI *a)
     }
 
     width = msb + 1 - lsb;
+    t_rd = load_reg(s, a->rd);
     if (a->rn == 15) {
         /* BFC */
-        t_in = tcg_constant_i32(0);
+        tcg_gen_deposit_z_i32(t_rd, t_rd, lsb, width);
     } else {
         /* BFI */
-        t_in = load_reg(s, a->rn);
+        tcg_gen_deposit_i32(t_rd, t_rd, load_reg(s, a->rn), lsb, width);
     }
-    t_rd = load_reg(s, a->rd);
-    tcg_gen_deposit_i32(t_rd, t_rd, t_in, lsb, width);
     store_reg(s, a->rd, t_rd);
     return true;
 }
-- 
2.41.0