[Qemu-devel] [PATCH v7 2/6] target-arm: Implement ARMv8 VSEL instruction.

[Will Newton <will.newton@linaro.org>]

This adds support for the VSEL floating point selection instruction
which was added in ARMv8.
---
 target-arm/translate.c | 135 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 134 insertions(+), 1 deletion(-)

Changes in v7:
 - Break out VSEL handling into a function
 - Properly sign extend VF and NF to 64bit
 - Use extract32 to decode insn
 - Fix brace style

diff --git a/target-arm/translate.c b/target-arm/translate.c
index f63e89d..0a22ad8 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -2614,6 +2614,139 @@ static TCGv_i32 gen_load_and_replicate(DisasContext *s, TCGv_i32 addr, int size)
     return tmp;
 }
 
+static int handle_vsel(uint32_t insn, uint32_t rd, uint32_t rn, uint32_t rm,
+                       uint32_t dp)
+{
+    uint32_t cc = extract32(insn, 20, 2);
+
+    if (dp) {
+        TCGv_i64 frn, frm, dest;
+        TCGv_i64 tmp, zero, zf, nf, vf;
+
+        zero = tcg_const_i64(0);
+
+        frn = tcg_temp_new_i64();
+        frm = tcg_temp_new_i64();
+        dest = tcg_temp_new_i64();
+
+        zf = tcg_temp_new_i64();
+        nf = tcg_temp_new_i64();
+        vf = tcg_temp_new_i64();
+
+        tcg_gen_extu_i32_i64(zf, cpu_ZF);
+        tcg_gen_ext_i32_i64(nf, cpu_NF);
+        tcg_gen_ext_i32_i64(vf, cpu_VF);
+
+        tcg_gen_ld_f64(frn, cpu_env, vfp_reg_offset(dp, rn));
+        tcg_gen_ld_f64(frm, cpu_env, vfp_reg_offset(dp, rm));
+        switch (cc) {
+        case 0: /* eq: Z */
+            tcg_gen_movcond_i64(TCG_COND_EQ, dest, zf, zero,
+                                frn, frm);
+            break;
+        case 1: /* vs: V */
+            tcg_gen_movcond_i64(TCG_COND_LT, dest, vf, zero,
+                                frn, frm);
+            break;
+        case 2: /* ge: N == V -> N ^ V == 0 */
+            tmp = tcg_temp_new_i64();
+            tcg_gen_xor_i64(tmp, vf, nf);
+            tcg_gen_movcond_i64(TCG_COND_GE, dest, tmp, zero,
+                                frn, frm);
+            tcg_temp_free_i64(tmp);
+            break;
+        case 3: /* gt: !Z && N == V */
+            tcg_gen_movcond_i64(TCG_COND_NE, dest, zf, zero,
+                                frn, frm);
+            tmp = tcg_temp_new_i64();
+            tcg_gen_xor_i64(tmp, vf, nf);
+            tcg_gen_movcond_i64(TCG_COND_GE, dest, tmp, zero,
+                                dest, frm);
+            tcg_temp_free_i64(tmp);
+            break;
+        }
+        tcg_gen_st_f64(dest, cpu_env, vfp_reg_offset(dp, rd));
+        tcg_temp_free_i64(frn);
+        tcg_temp_free_i64(frm);
+        tcg_temp_free_i64(dest);
+
+        tcg_temp_free_i64(zf);
+        tcg_temp_free_i64(nf);
+        tcg_temp_free_i64(vf);
+
+        tcg_temp_free_i64(zero);
+    } else {
+        TCGv_i32 frn, frm, dest;
+        TCGv_i32 tmp, zero;
+
+        zero = tcg_const_i32(0);
+
+        frn = tcg_temp_new_i32();
+        frm = tcg_temp_new_i32();
+        dest = tcg_temp_new_i32();
+        tcg_gen_ld_f32(frn, cpu_env, vfp_reg_offset(dp, rn));
+        tcg_gen_ld_f32(frm, cpu_env, vfp_reg_offset(dp, rm));
+        switch (cc) {
+        case 0: /* eq: Z */
+            tcg_gen_movcond_i32(TCG_COND_EQ, dest, cpu_ZF, zero,
+                                frn, frm);
+            break;
+        case 1: /* vs: V */
+            tcg_gen_movcond_i32(TCG_COND_LT, dest, cpu_VF, zero,
+                                frn, frm);
+            break;
+        case 2: /* ge: N == V -> N ^ V == 0 */
+            tmp = tcg_temp_new_i32();
+            tcg_gen_xor_i32(tmp, cpu_VF, cpu_NF);
+            tcg_gen_movcond_i32(TCG_COND_GE, dest, tmp, zero,
+                                frn, frm);
+            tcg_temp_free_i32(tmp);
+            break;
+        case 3: /* gt: !Z && N == V */
+            tcg_gen_movcond_i32(TCG_COND_NE, dest, cpu_ZF, zero,
+                                frn, frm);
+            tmp = tcg_temp_new_i32();
+            tcg_gen_xor_i32(tmp, cpu_VF, cpu_NF);
+            tcg_gen_movcond_i32(TCG_COND_GE, dest, tmp, zero,
+                                dest, frm);
+            tcg_temp_free_i32(tmp);
+            break;
+        }
+        tcg_gen_st_f32(dest, cpu_env, vfp_reg_offset(dp, rd));
+        tcg_temp_free_i32(frn);
+        tcg_temp_free_i32(frm);
+        tcg_temp_free_i32(dest);
+
+        tcg_temp_free_i32(zero);
+    }
+
+    return 0;
+}
+
+static int disas_vfp_v8_insn(CPUARMState *env, DisasContext *s, uint32_t insn)
+{
+    uint32_t rd, rn, rm, dp = extract32(insn, 8, 1);
+
+    if (!arm_feature(env, ARM_FEATURE_V8)) {
+        return 1;
+    }
+
+    if (dp) {
+        VFP_DREG_D(rd, insn);
+        VFP_DREG_N(rn, insn);
+        VFP_DREG_M(rm, insn);
+    } else {
+        rd = VFP_SREG_D(insn);
+        rn = VFP_SREG_N(insn);
+        rm = VFP_SREG_M(insn);
+    }
+
+    if ((insn & 0x0f800e50) == 0x0e000a00) {
+        return handle_vsel(insn, rd, rn, rm, dp);
+    }
+    return 1;
+}
+
 /* Disassemble a VFP instruction.  Returns nonzero if an error occurred
    (ie. an undefined instruction).  */
 static int disas_vfp_insn(CPUARMState * env, DisasContext *s, uint32_t insn)
@@ -2641,7 +2774,7 @@ static int disas_vfp_insn(CPUARMState * env, DisasContext *s, uint32_t insn)
         /* Encodings with T=1 (Thumb) or unconditional (ARM):
          * only used in v8 and above.
          */
-        return 1;
+        return disas_vfp_v8_insn(env, s, insn);
     }
 
     dp = ((insn & 0xf00) == 0xb00);
-- 
1.8.1.4