target/arm: Use tcg_gen_gvec_mov for clear_vec_high

The 8-byte store for the end a !is_q operation can be
merged with the other stores.  Use a no-op vector move
to trigger the expand_clr portion of tcg_gen_gvec_mov.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200519212453.28494-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 991e451644c6b7f16a0de198eacead9e145f25c5..4f6edb28927265a9e0aa103e3bbd77c036f62531 100644 (file)
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -496,14 +496,8 @@ static void clear_vec_high(DisasContext *s, bool is_q, int rd)
     unsigned ofs = fp_reg_offset(s, rd, MO_64);
     unsigned vsz = vec_full_reg_size(s);
 
-    if (!is_q) {
-        TCGv_i64 tcg_zero = tcg_const_i64(0);
-        tcg_gen_st_i64(tcg_zero, cpu_env, ofs + 8);
-        tcg_temp_free_i64(tcg_zero);
-    }
-    if (vsz > 16) {
-        tcg_gen_gvec_dup_imm(MO_64, ofs + 16, vsz - 16, vsz - 16, 0);
-    }
+    /* Nop move, with side effect of clearing the tail. */
+    tcg_gen_gvec_mov(MO_64, ofs, ofs, is_q ? 16 : 8, vsz);
 }
 
 void write_fp_dreg(DisasContext *s, int reg, TCGv_i64 v)