diff options
author | Alexander Graf <agraf@suse.de> | 2013-12-17 19:42:36 +0000 |
---|---|---|
committer | Peter Maydell <peter.maydell@linaro.org> | 2013-12-17 20:12:51 +0000 |
commit | 71b46089303beb7d52a0b9397f5c286a7e66275f (patch) | |
tree | 2577ca17aedf39b6f6e8a5f806f31cd7ee1b05d3 /target-arm | |
parent | e80c502023d332fb60866eb378e715ab3f158b72 (diff) | |
download | qemu-71b46089303beb7d52a0b9397f5c286a7e66275f.zip qemu-71b46089303beb7d52a0b9397f5c286a7e66275f.tar.gz qemu-71b46089303beb7d52a0b9397f5c286a7e66275f.tar.bz2 |
target-arm: A64: add support for logical (immediate) insns
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>
Diffstat (limited to 'target-arm')
-rw-r--r-- | target-arm/translate-a64.c | 175 |
1 files changed, 173 insertions, 2 deletions
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c index 2bb1795..0a76130 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) */ |