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authorAlexander Graf <agraf@suse.de>2013-11-28 11:11:30 +0100
committerPeter Maydell <peter.maydell@linaro.org>2013-12-06 17:24:03 +0000
commitb0c34d44f697cbf17dac64df06344a1243602a2d (patch)
treea31580fbea3cf86366fe423192d84c65a89dc0c2
parentdbc43bc22ebea7f11af2f3e82bf73a8b4245cd17 (diff)
downloadqemu-arm-a64-second-set.tar.gz
target-arm: A64: add support for logical (immediate) insnsa64-second-set
This patch adds support for C3.4.4 Logical (immediate), which include AND, ANDS, ORR, EOR. Signed-off-by: Alexander Graf <agraf@suse.de> [claudio: adapted to new decoder, function renaming, removed a TCG temp variable] Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org> [PMM: cleaned up some unnecessary code in logic_imm_decode_wmask and added clarifying commentary on what it's actually doing. Dropped an ext32u that's not needed if we've just done an AND.] Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <rth@twiddle.net>
-rw-r--r--target-arm/translate-a64.c175
1 files changed, 173 insertions, 2 deletions
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index d9bf706a58..03608db243 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -201,6 +201,21 @@ static TCGv_i64 new_tmp_a64_zero(DisasContext *s)
return t;
}
+/*
+ * Register access functions
+ *
+ * These functions are used for directly accessing a register in where
+ * changes to the final register value are likely to be made. If you
+ * need to use a register for temporary calculation (e.g. index type
+ * operations) use the read_* form.
+ *
+ * B1.2.1 Register mappings
+ *
+ * In instruction register encoding 31 can refer to ZR (zero register) or
+ * the SP (stack pointer) depending on context. In QEMU's case we map SP
+ * to cpu_X[31] and ZR accesses to a temporary which can be discarded.
+ * This is the point of the _sp forms.
+ */
static TCGv_i64 cpu_reg(DisasContext *s, int reg)
{
if (reg == 31) {
@@ -210,6 +225,12 @@ static TCGv_i64 cpu_reg(DisasContext *s, int reg)
}
}
+/* register access for when 31 == SP */
+static TCGv_i64 cpu_reg_sp(DisasContext *s, int reg)
+{
+ return cpu_X[reg];
+}
+
/* read a cpu register in 32bit/64bit mode. Returns a TCGv_i64
* representing the register contents. This TCGv is an auto-freed
* temporary so it need not be explicitly freed, and may be modified.
@@ -686,10 +707,160 @@ static void disas_add_sub_imm(DisasContext *s, uint32_t insn)
unsupported_encoding(s, insn);
}
-/* Logical (immediate) */
+/* The input should be a value in the bottom e bits (with higher
+ * bits zero); returns that value replicated into every element
+ * of size e in a 64 bit integer.
+ */
+static uint64_t bitfield_replicate(uint64_t mask, unsigned int e)
+{
+ assert(e != 0);
+ while (e < 64) {
+ mask |= mask << e;
+ e *= 2;
+ }
+ return mask;
+}
+
+/* Return a value with the bottom len bits set (where 0 < len <= 64) */
+static inline uint64_t bitmask64(unsigned int length)
+{
+ assert(length > 0 && length <= 64);
+ return ~0ULL >> (64 - length);
+}
+
+/* Simplified variant of pseudocode DecodeBitMasks() for the case where we
+ * only require the wmask. Returns false if the imms/immr/immn are a reserved
+ * value (ie should cause a guest UNDEF exception), and true if they are
+ * valid, in which case the decoded bit pattern is written to result.
+ */
+static bool logic_imm_decode_wmask(uint64_t *result, unsigned int immn,
+ unsigned int imms, unsigned int immr)
+{
+ uint64_t mask;
+ unsigned e, levels, s, r;
+ int len;
+
+ assert(immn < 2 && imms < 64 && immr < 64);
+
+ /* The bit patterns we create here are 64 bit patterns which
+ * are vectors of identical elements of size e = 2, 4, 8, 16, 32 or
+ * 64 bits each. Each element contains the same value: a run
+ * of between 1 and e-1 non-zero bits, rotated within the
+ * element by between 0 and e-1 bits.
+ *
+ * The element size and run length are encoded into immn (1 bit)
+ * and imms (6 bits) as follows:
+ * 64 bit elements: immn = 1, imms = <length of run - 1>
+ * 32 bit elements: immn = 0, imms = 0 : <length of run - 1>
+ * 16 bit elements: immn = 0, imms = 10 : <length of run - 1>
+ * 8 bit elements: immn = 0, imms = 110 : <length of run - 1>
+ * 4 bit elements: immn = 0, imms = 1110 : <length of run - 1>
+ * 2 bit elements: immn = 0, imms = 11110 : <length of run - 1>
+ * Notice that immn = 0, imms = 11111x is the only combination
+ * not covered by one of the above options; this is reserved.
+ * Further, <length of run - 1> all-ones is a reserved pattern.
+ *
+ * In all cases the rotation is by immr % e (and immr is 6 bits).
+ */
+
+ /* First determine the element size */
+ len = 31 - clz32((immn << 6) | (~imms & 0x3f));
+ if (len < 1) {
+ /* This is the immn == 0, imms == 0x11111x case */
+ return false;
+ }
+ e = 1 << len;
+
+ levels = e - 1;
+ s = imms & levels;
+ r = immr & levels;
+
+ if (s == levels) {
+ /* <length of run - 1> mustn't be all-ones. */
+ return false;
+ }
+
+ /* Create the value of one element: s+1 set bits rotated
+ * by r within the element (which is e bits wide)...
+ */
+ mask = bitmask64(s + 1);
+ mask = (mask >> r) | (mask << (e - r));
+ /* ...then replicate the element over the whole 64 bit value */
+ mask = bitfield_replicate(mask, e);
+ *result = mask;
+ return true;
+}
+
+/* C3.4.4 Logical (immediate)
+ * 31 30 29 28 23 22 21 16 15 10 9 5 4 0
+ * +----+-----+-------------+---+------+------+------+------+
+ * | sf | opc | 1 0 0 1 0 0 | N | immr | imms | Rn | Rd |
+ * +----+-----+-------------+---+------+------+------+------+
+ */
static void disas_logic_imm(DisasContext *s, uint32_t insn)
{
- unsupported_encoding(s, insn);
+ unsigned int sf, opc, is_n, immr, imms, rn, rd;
+ TCGv_i64 tcg_rd, tcg_rn;
+ uint64_t wmask;
+ bool is_and = false;
+
+ sf = extract32(insn, 31, 1);
+ opc = extract32(insn, 29, 2);
+ is_n = extract32(insn, 22, 1);
+ immr = extract32(insn, 16, 6);
+ imms = extract32(insn, 10, 6);
+ rn = extract32(insn, 5, 5);
+ rd = extract32(insn, 0, 5);
+
+ if (!sf && is_n) {
+ unallocated_encoding(s);
+ return;
+ }
+
+ if (opc == 0x3) { /* ANDS */
+ tcg_rd = cpu_reg(s, rd);
+ } else {
+ tcg_rd = cpu_reg_sp(s, rd);
+ }
+ tcg_rn = cpu_reg(s, rn);
+
+ if (!logic_imm_decode_wmask(&wmask, is_n, imms, immr)) {
+ /* some immediate field values are reserved */
+ unallocated_encoding(s);
+ return;
+ }
+
+ if (!sf) {
+ wmask &= 0xffffffff;
+ }
+
+ switch (opc) {
+ case 0x3: /* ANDS */
+ case 0x0: /* AND */
+ tcg_gen_andi_i64(tcg_rd, tcg_rn, wmask);
+ is_and = true;
+ break;
+ case 0x1: /* ORR */
+ tcg_gen_ori_i64(tcg_rd, tcg_rn, wmask);
+ break;
+ case 0x2: /* EOR */
+ tcg_gen_xori_i64(tcg_rd, tcg_rn, wmask);
+ break;
+ default:
+ assert(FALSE); /* must handle all above */
+ break;
+ }
+
+ if (!sf && !is_and) {
+ /* zero extend final result; we know we can skip this for AND
+ * since the immediate had the high 32 bits clear.
+ */
+ tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
+ }
+
+ if (opc == 3) { /* ANDS */
+ gen_logic_CC(sf, tcg_rd);
+ }
}
/* Move wide (immediate) */