[PATCH 43/76] target/arm: Handle FPCR.NEP for FCVTXN (scalar)

[Peter Maydell]

Unlike the other users of do_2misc_narrow_scalar(), FCVTXN (scalar)
is always double-to-single and must honour FPCR.NEP.  Implement this
directly in a trans function rather than using
do_2misc_narrow_scalar().

We still need gen_fcvtxn_sd() and the f_scalar_fcvtxn[] array for
the FCVTXN (vector) insn, so we move those down in the file to
where they are used.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/tcg/translate-a64.c | 43 ++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index 7412787b6b6..6dc5648cb1b 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -9258,24 +9258,21 @@ static ArithOneOp * const f_scalar_uqxtn[] = {
 };
 TRANS(UQXTN_s, do_2misc_narrow_scalar, a, f_scalar_uqxtn)
 
-static void gen_fcvtxn_sd(TCGv_i64 d, TCGv_i64 n)
+static bool trans_FCVTXN_s(DisasContext *s, arg_rr_e *a)
 {
-    /*
-     * 64 bit to 32 bit float conversion
-     * with von Neumann rounding (round to odd)
-     */
-    TCGv_i32 tmp = tcg_temp_new_i32();
-    gen_helper_fcvtx_f64_to_f32(tmp, n, fpstatus_ptr(FPST_FPCR_A64));
-    tcg_gen_extu_i32_i64(d, tmp);
+    if (fp_access_check(s)) {
+        /*
+         * 64 bit to 32 bit float conversion
+         * with von Neumann rounding (round to odd)
+         */
+        TCGv_i64 src = read_fp_dreg(s, a->rn);
+        TCGv_i32 dst = tcg_temp_new_i32();
+        gen_helper_fcvtx_f64_to_f32(dst, src, fpstatus_ptr(FPST_FPCR_A64));
+        write_fp_sreg_merging(s, a->rd, a->rd, dst);
+    }
+    return true;
 }
 
-static ArithOneOp * const f_scalar_fcvtxn[] = {
-    NULL,
-    NULL,
-    gen_fcvtxn_sd,
-};
-TRANS(FCVTXN_s, do_2misc_narrow_scalar, a, f_scalar_fcvtxn)
-
 #undef WRAP_ENV
 
 static bool do_gvec_fn2(DisasContext *s, arg_qrr_e *a, GVecGen2Fn *fn)
@@ -9377,11 +9374,27 @@ static void gen_fcvtn_sd(TCGv_i64 d, TCGv_i64 n)
     tcg_gen_extu_i32_i64(d, tmp);
 }
 
+static void gen_fcvtxn_sd(TCGv_i64 d, TCGv_i64 n)
+{
+    /*
+     * 64 bit to 32 bit float conversion
+     * with von Neumann rounding (round to odd)
+     */
+    TCGv_i32 tmp = tcg_temp_new_i32();
+    gen_helper_fcvtx_f64_to_f32(tmp, n, fpstatus_ptr(FPST_FPCR_A64));
+    tcg_gen_extu_i32_i64(d, tmp);
+}
+
 static ArithOneOp * const f_vector_fcvtn[] = {
     NULL,
     gen_fcvtn_hs,
     gen_fcvtn_sd,
 };
+static ArithOneOp * const f_scalar_fcvtxn[] = {
+    NULL,
+    NULL,
+    gen_fcvtxn_sd,
+};
 TRANS(FCVTN_v, do_2misc_narrow_vector, a, f_vector_fcvtn)
 TRANS(FCVTXN_v, do_2misc_narrow_vector, a, f_scalar_fcvtxn)
 
-- 
2.34.1