[Qemu-devel] [PATCH v2 35/42] target/arm: Convert the VCVT-to-f16 insns to decodetree

[Peter Maydell]

Convert the VCVTT and VCVTB instructions which convert from
f32 and f64 to f16 to decodetree.

Since we're no longer constrained to the old decoder's style
using cpu_F0s and cpu_F0d we can perform a direct 16 bit
store of the right half of the input single-precision register
rather than doing a load/modify/store sequence on the full
32 bits.

Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
---
 target/arm/translate-vfp.inc.c | 62 ++++++++++++++++++++++++++
 target/arm/translate.c         | 79 +---------------------------------
 target/arm/vfp.decode          |  6 +++
 3 files changed, 69 insertions(+), 78 deletions(-)

diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c
index 732bf6020a9..a19ede86719 100644
--- a/target/arm/translate-vfp.inc.c
+++ b/target/arm/translate-vfp.inc.c
@@ -2095,3 +2095,65 @@ static bool trans_VCVT_f64_f16(DisasContext *s, 
arg_VCVT_f64_f16 *a)
     tcg_temp_free_i64(vd);
     return true;
 }
+
+static bool trans_VCVT_f16_f32(DisasContext *s, arg_VCVT_f16_f32 *a)
+{
+    TCGv_ptr fpst;
+    TCGv_i32 ahp_mode;
+    TCGv_i32 tmp;
+
+    if (!dc_isar_feature(aa32_fp16_spconv, s)) {
+        return false;
+    }
+
+    if (!vfp_access_check(s)) {
+        return true;
+    }
+
+    fpst = get_fpstatus_ptr(false);
+    ahp_mode = get_ahp_flag();
+    tmp = tcg_temp_new_i32();
+
+    neon_load_reg32(tmp, a->vm);
+    gen_helper_vfp_fcvt_f32_to_f16(tmp, tmp, fpst, ahp_mode);
+    tcg_gen_st16_i32(tmp, cpu_env, vfp_f16_offset(a->vd, a->t));
+    tcg_temp_free_i32(ahp_mode);
+    tcg_temp_free_ptr(fpst);
+    tcg_temp_free_i32(tmp);
+    return true;
+}
+
+static bool trans_VCVT_f16_f64(DisasContext *s, arg_VCVT_f16_f64 *a)
+{
+    TCGv_ptr fpst;
+    TCGv_i32 ahp_mode;
+    TCGv_i32 tmp;
+    TCGv_i64 vm;
+
+    if (!dc_isar_feature(aa32_fp16_dpconv, s)) {
+        return false;
+    }
+
+    /* UNDEF accesses to D16-D31 if they don't exist. */
+    if (!dc_isar_feature(aa32_fp_d32, s) && (a->vm  & 0x10)) {
+        return false;
+    }
+
+    if (!vfp_access_check(s)) {
+        return true;
+    }
+
+    fpst = get_fpstatus_ptr(false);
+    ahp_mode = get_ahp_flag();
+    tmp = tcg_temp_new_i32();
+    vm = tcg_temp_new_i64();
+
+    neon_load_reg64(vm, a->vm);
+    gen_helper_vfp_fcvt_f64_to_f16(tmp, vm, fpst, ahp_mode);
+    tcg_temp_free_i64(vm);
+    tcg_gen_st16_i32(tmp, cpu_env, vfp_f16_offset(a->vd, a->t));
+    tcg_temp_free_i32(ahp_mode);
+    tcg_temp_free_ptr(fpst);
+    tcg_temp_free_i32(tmp);
+    return true;
+}
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 34a82cfa424..143b250a996 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -2963,20 +2963,6 @@ static int disas_dsp_insn(DisasContext *s, uint32_t insn)
 #define VFP_SREG_M(insn) VFP_SREG(insn,  0,  5)
 #define VFP_DREG_M(reg, insn) VFP_DREG(reg, insn,  0,  5)
 
-/* Move between integer and VFP cores.  */
-static TCGv_i32 gen_vfp_mrs(void)
-{
-    TCGv_i32 tmp = tcg_temp_new_i32();
-    tcg_gen_mov_i32(tmp, cpu_F0s);
-    return tmp;
-}
-
-static void gen_vfp_msr(TCGv_i32 tmp)
-{
-    tcg_gen_mov_i32(cpu_F0s, tmp);
-    tcg_temp_free_i32(tmp);
-}
-
 static void gen_neon_dup_low16(TCGv_i32 var)
 {
     TCGv_i32 tmp = tcg_temp_new_i32();
@@ -3003,8 +2989,6 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
 {
     uint32_t rd, rn, rm, op, delta_d, delta_m, bank_mask;
     int dp, veclen;
-    TCGv_i32 tmp;
-    TCGv_i32 tmp2;
 
     if (!arm_dc_feature(s, ARM_FEATURE_VFP)) {
         return 1;
@@ -3066,8 +3050,7 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
                 return 1;
             case 15:
                 switch (rn) {
-                case 0 ... 5:
-                case 8 ... 11:
+                case 0 ... 11:
                     /* Already handled by decodetree */
                     return 1;
                 default:
@@ -3080,20 +3063,6 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
             if (op == 15) {
                 /* rn is opcode, encoded as per VFP_SREG_N. */
                 switch (rn) {
-                case 0x06: /* vcvtb.f16.f32, vcvtb.f16.f64 */
-                case 0x07: /* vcvtt.f16.f32, vcvtt.f16.f64 */
-                    if (dp) {
-                        if (!dc_isar_feature(aa32_fp16_dpconv, s)) {
-                            return 1;
-                        }
-                    } else {
-                        if (!dc_isar_feature(aa32_fp16_spconv, s)) {
-                            return 1;
-                        }
-                    }
-                    rd_is_dp = false;
-                    break;
-
                 case 0x0c: /* vrintr */
                 case 0x0d: /* vrintz */
                 case 0x0e: /* vrintx */
@@ -3221,52 +3190,6 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
                 switch (op) {
                 case 15: /* extension space */
                     switch (rn) {
-                    case 6: /* vcvtb.f16.f32, vcvtb.f16.f64 */
-                    {
-                        TCGv_ptr fpst = get_fpstatus_ptr(false);
-                        TCGv_i32 ahp = get_ahp_flag();
-                        tmp = tcg_temp_new_i32();
-
-                        if (dp) {
-                            gen_helper_vfp_fcvt_f64_to_f16(tmp, cpu_F0d,
-                                                           fpst, ahp);
-                        } else {
-                            gen_helper_vfp_fcvt_f32_to_f16(tmp, cpu_F0s,
-                                                           fpst, ahp);
-                        }
-                        tcg_temp_free_i32(ahp);
-                        tcg_temp_free_ptr(fpst);
-                        gen_mov_F0_vreg(0, rd);
-                        tmp2 = gen_vfp_mrs();
-                        tcg_gen_andi_i32(tmp2, tmp2, 0xffff0000);
-                        tcg_gen_or_i32(tmp, tmp, tmp2);
-                        tcg_temp_free_i32(tmp2);
-                        gen_vfp_msr(tmp);
-                        break;
-                    }
-                    case 7: /* vcvtt.f16.f32, vcvtt.f16.f64 */
-                    {
-                        TCGv_ptr fpst = get_fpstatus_ptr(false);
-                        TCGv_i32 ahp = get_ahp_flag();
-                        tmp = tcg_temp_new_i32();
-                        if (dp) {
-                            gen_helper_vfp_fcvt_f64_to_f16(tmp, cpu_F0d,
-                                                           fpst, ahp);
-                        } else {
-                            gen_helper_vfp_fcvt_f32_to_f16(tmp, cpu_F0s,
-                                                           fpst, ahp);
-                        }
-                        tcg_temp_free_i32(ahp);
-                        tcg_temp_free_ptr(fpst);
-                        tcg_gen_shli_i32(tmp, tmp, 16);
-                        gen_mov_F0_vreg(0, rd);
-                        tmp2 = gen_vfp_mrs();
-                        tcg_gen_ext16u_i32(tmp2, tmp2);
-                        tcg_gen_or_i32(tmp, tmp, tmp2);
-                        tcg_temp_free_i32(tmp2);
-                        gen_vfp_msr(tmp);
-                        break;
-                    }
                     case 12: /* vrintr */
                     {
                         TCGv_ptr fpst = get_fpstatus_ptr(0);
diff --git a/target/arm/vfp.decode b/target/arm/vfp.decode
index 53d9544f7cd..b88d1d06f02 100644
--- a/target/arm/vfp.decode
+++ b/target/arm/vfp.decode
@@ -187,3 +187,9 @@ VCVT_f32_f16 ---- 1110 1.11 0010 .... 1010 t:1 1.0 .... \
              vd=%vd_sp vm=%vm_sp
 VCVT_f64_f16 ---- 1110 1.11 0010 .... 1011 t:1 1.0 .... \
              vd=%vd_dp vm=%vm_sp
+
+# VCVTB and VCVTT to f16: Vd format is always vd_sp; Vm format depends on size 
bit
+VCVT_f16_f32 ---- 1110 1.11 0011 .... 1010 t:1 1.0 .... \
+             vd=%vd_sp vm=%vm_sp
+VCVT_f16_f64 ---- 1110 1.11 0011 .... 1011 t:1 1.0 .... \
+             vd=%vd_sp vm=%vm_dp
-- 
2.20.1