[Qemu-devel] [PULL 39/62] target-arm: A64: add support for logical (shifted register)

[Peter Maydell <peter.maydell@linaro.org>]

From: Alexander Graf <agraf@suse.de>

Add support for the instructions described in "C3.5.10 Logical
(shifted register)".

We store the flags in the same locations as the 32 bit decoder.
This is slightly awkward when calculating 64 bit results, but seems
a better tradeoff than having to rework the whole 32 bit decoder
and also make 32 bit result calculation in A64 awkward.

Signed-off-by: Alexander Graf <agraf@suse.de>
[claudio: some refactoring to avoid hidden allocation of temps,
	  rework flags, use enums for shift types,
	  renaming of functions]
Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
[PMM: Use TCG's andc/orc/eqv ops rather than manually inverting]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
---
 target-arm/translate-a64.c | 197 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 191 insertions(+), 6 deletions(-)

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 13eedf4..a459ce6 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -36,7 +36,7 @@
 
 static TCGv_i64 cpu_X[32];
 static TCGv_i64 cpu_pc;
-static TCGv_i32 pstate;
+static TCGv_i32 cpu_NF, cpu_ZF, cpu_CF, cpu_VF;
 
 static const char *regnames[] = {
     "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
@@ -45,6 +45,13 @@ static const char *regnames[] = {
     "x24", "x25", "x26", "x27", "x28", "x29", "lr", "sp"
 };
 
+enum a64_shift_type {
+    A64_SHIFT_TYPE_LSL = 0,
+    A64_SHIFT_TYPE_LSR = 1,
+    A64_SHIFT_TYPE_ASR = 2,
+    A64_SHIFT_TYPE_ROR = 3
+};
+
 /* initialize TCG globals.  */
 void a64_translate_init(void)
 {
@@ -59,9 +66,10 @@ void a64_translate_init(void)
                                           regnames[i]);
     }
 
-    pstate = tcg_global_mem_new_i32(TCG_AREG0,
-                                    offsetof(CPUARMState, pstate),
-                                    "pstate");
+    cpu_NF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, NF), "NF");
+    cpu_ZF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, ZF), "ZF");
+    cpu_CF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, CF), "CF");
+    cpu_VF = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUARMState, VF), "VF");
 }
 
 void aarch64_cpu_dump_state(CPUState *cs, FILE *f,
@@ -221,6 +229,33 @@ static TCGv_i64 read_cpu_reg(DisasContext *s, int reg, int sf)
     return v;
 }
 
+/* Set ZF and NF based on a 64 bit result. This is alas fiddlier
+ * than the 32 bit equivalent.
+ */
+static inline void gen_set_NZ64(TCGv_i64 result)
+{
+    TCGv_i64 flag = tcg_temp_new_i64();
+
+    tcg_gen_setcondi_i64(TCG_COND_NE, flag, result, 0);
+    tcg_gen_trunc_i64_i32(cpu_ZF, flag);
+    tcg_gen_shri_i64(flag, result, 32);
+    tcg_gen_trunc_i64_i32(cpu_NF, flag);
+    tcg_temp_free_i64(flag);
+}
+
+/* Set NZCV as for a logical operation: NZ as per result, CV cleared. */
+static inline void gen_logic_CC(int sf, TCGv_i64 result)
+{
+    if (sf) {
+        gen_set_NZ64(result);
+    } else {
+        tcg_gen_trunc_i64_i32(cpu_ZF, result);
+        tcg_gen_trunc_i64_i32(cpu_NF, result);
+    }
+    tcg_gen_movi_i32(cpu_CF, 0);
+    tcg_gen_movi_i32(cpu_VF, 0);
+}
+
 /*
  * the instruction disassembly implemented here matches
  * the instruction encoding classifications in chapter 3 (C3)
@@ -682,10 +717,160 @@ static void disas_data_proc_imm(DisasContext *s, uint32_t insn)
     }
 }
 
-/* Logical (shifted register) */
+/* Shift a TCGv src by TCGv shift_amount, put result in dst.
+ * Note that it is the caller's responsibility to ensure that the
+ * shift amount is in range (ie 0..31 or 0..63) and provide the ARM
+ * mandated semantics for out of range shifts.
+ */
+static void shift_reg(TCGv_i64 dst, TCGv_i64 src, int sf,
+                      enum a64_shift_type shift_type, TCGv_i64 shift_amount)
+{
+    switch (shift_type) {
+    case A64_SHIFT_TYPE_LSL:
+        tcg_gen_shl_i64(dst, src, shift_amount);
+        break;
+    case A64_SHIFT_TYPE_LSR:
+        tcg_gen_shr_i64(dst, src, shift_amount);
+        break;
+    case A64_SHIFT_TYPE_ASR:
+        if (!sf) {
+            tcg_gen_ext32s_i64(dst, src);
+        }
+        tcg_gen_sar_i64(dst, sf ? src : dst, shift_amount);
+        break;
+    case A64_SHIFT_TYPE_ROR:
+        if (sf) {
+            tcg_gen_rotr_i64(dst, src, shift_amount);
+        } else {
+            TCGv_i32 t0, t1;
+            t0 = tcg_temp_new_i32();
+            t1 = tcg_temp_new_i32();
+            tcg_gen_trunc_i64_i32(t0, src);
+            tcg_gen_trunc_i64_i32(t1, shift_amount);
+            tcg_gen_rotr_i32(t0, t0, t1);
+            tcg_gen_extu_i32_i64(dst, t0);
+            tcg_temp_free_i32(t0);
+            tcg_temp_free_i32(t1);
+        }
+        break;
+    default:
+        assert(FALSE); /* all shift types should be handled */
+        break;
+    }
+
+    if (!sf) { /* zero extend final result */
+        tcg_gen_ext32u_i64(dst, dst);
+    }
+}
+
+/* Shift a TCGv src by immediate, put result in dst.
+ * The shift amount must be in range (this should always be true as the
+ * relevant instructions will UNDEF on bad shift immediates).
+ */
+static void shift_reg_imm(TCGv_i64 dst, TCGv_i64 src, int sf,
+                          enum a64_shift_type shift_type, unsigned int shift_i)
+{
+    assert(shift_i < (sf ? 64 : 32));
+
+    if (shift_i == 0) {
+        tcg_gen_mov_i64(dst, src);
+    } else {
+        TCGv_i64 shift_const;
+
+        shift_const = tcg_const_i64(shift_i);
+        shift_reg(dst, src, sf, shift_type, shift_const);
+        tcg_temp_free_i64(shift_const);
+    }
+}
+
+/* C3.5.10 Logical (shifted register)
+ *   31  30 29 28       24 23   22 21  20  16 15    10 9    5 4    0
+ * +----+-----+-----------+-------+---+------+--------+------+------+
+ * | sf | opc | 0 1 0 1 0 | shift | N |  Rm  |  imm6  |  Rn  |  Rd  |
+ * +----+-----+-----------+-------+---+------+--------+------+------+
+ */
 static void disas_logic_reg(DisasContext *s, uint32_t insn)
 {
-    unsupported_encoding(s, insn);
+    TCGv_i64 tcg_rd, tcg_rn, tcg_rm;
+    unsigned int sf, opc, shift_type, invert, rm, shift_amount, rn, rd;
+
+    sf = extract32(insn, 31, 1);
+    opc = extract32(insn, 29, 2);
+    shift_type = extract32(insn, 22, 2);
+    invert = extract32(insn, 21, 1);
+    rm = extract32(insn, 16, 5);
+    shift_amount = extract32(insn, 10, 6);
+    rn = extract32(insn, 5, 5);
+    rd = extract32(insn, 0, 5);
+
+    if (!sf && (shift_amount & (1 << 5))) {
+        unallocated_encoding(s);
+        return;
+    }
+
+    tcg_rd = cpu_reg(s, rd);
+
+    if (opc == 1 && shift_amount == 0 && shift_type == 0 && rn == 31) {
+        /* Unshifted ORR and ORN with WZR/XZR is the standard encoding for
+         * register-register MOV and MVN, so it is worth special casing.
+         */
+        tcg_rm = cpu_reg(s, rm);
+        if (invert) {
+            tcg_gen_not_i64(tcg_rd, tcg_rm);
+            if (!sf) {
+                tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
+            }
+        } else {
+            if (sf) {
+                tcg_gen_mov_i64(tcg_rd, tcg_rm);
+            } else {
+                tcg_gen_ext32u_i64(tcg_rd, tcg_rm);
+            }
+        }
+        return;
+    }
+
+    tcg_rm = read_cpu_reg(s, rm, sf);
+
+    if (shift_amount) {
+        shift_reg_imm(tcg_rm, tcg_rm, sf, shift_type, shift_amount);
+    }
+
+    tcg_rn = cpu_reg(s, rn);
+
+    switch (opc | (invert << 2)) {
+    case 0: /* AND */
+    case 3: /* ANDS */
+        tcg_gen_and_i64(tcg_rd, tcg_rn, tcg_rm);
+        break;
+    case 1: /* ORR */
+        tcg_gen_or_i64(tcg_rd, tcg_rn, tcg_rm);
+        break;
+    case 2: /* EOR */
+        tcg_gen_xor_i64(tcg_rd, tcg_rn, tcg_rm);
+        break;
+    case 4: /* BIC */
+    case 7: /* BICS */
+        tcg_gen_andc_i64(tcg_rd, tcg_rn, tcg_rm);
+        break;
+    case 5: /* ORN */
+        tcg_gen_orc_i64(tcg_rd, tcg_rn, tcg_rm);
+        break;
+    case 6: /* EON */
+        tcg_gen_eqv_i64(tcg_rd, tcg_rn, tcg_rm);
+        break;
+    default:
+        assert(FALSE);
+        break;
+    }
+
+    if (!sf) {
+        tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
+    }
+
+    if (opc == 3) {
+        gen_logic_CC(sf, tcg_rd);
+    }
 }
 
 /* Add/subtract (extended register) */
-- 
1.8.5