--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/cpu/aarch64/vm/immediate_aarch64.cpp Tue Jan 20 11:34:17 2015 -0800
@@ -0,0 +1,315 @@
+/*
+ * Copyright (c) 2014, Red Hat Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include <stdlib.h>
+#include "decode_aarch64.hpp"
+#include "immediate_aarch64.hpp"
+
+// there are at most 2^13 possible logical immediate encodings
+// however, some combinations of immr and imms are invalid
+static const unsigned LI_TABLE_SIZE = (1 << 13);
+
+static int li_table_entry_count;
+
+// for forward lookup we just use a direct array lookup
+// and assume that the cient has supplied a valid encoding
+// table[encoding] = immediate
+static u_int64_t LITable[LI_TABLE_SIZE];
+
+// for reverse lookup we need a sparse map so we store a table of
+// immediate and encoding pairs sorted by immediate value
+
+struct li_pair {
+ u_int64_t immediate;
+ u_int32_t encoding;
+};
+
+static struct li_pair InverseLITable[LI_TABLE_SIZE];
+
+// comparator to sort entries in the inverse table
+int compare_immediate_pair(const void *i1, const void *i2)
+{
+ struct li_pair *li1 = (struct li_pair *)i1;
+ struct li_pair *li2 = (struct li_pair *)i2;
+ if (li1->immediate < li2->immediate) {
+ return -1;
+ }
+ if (li1->immediate > li2->immediate) {
+ return 1;
+ }
+ return 0;
+}
+
+// helper functions used by expandLogicalImmediate
+
+// for i = 1, ... N result<i-1> = 1 other bits are zero
+static inline u_int64_t ones(int N)
+{
+ return (N == 64 ? (u_int64_t)-1UL : ((1UL << N) - 1));
+}
+
+// result<0> to val<N>
+static inline u_int64_t pickbit(u_int64_t val, int N)
+{
+ return pickbits64(val, N, N);
+}
+
+
+// SPEC bits(M*N) Replicate(bits(M) x, integer N);
+// this is just an educated guess
+
+u_int64_t replicate(u_int64_t bits, int nbits, int count)
+{
+ u_int64_t result = 0;
+ // nbits may be 64 in which case we want mask to be -1
+ u_int64_t mask = ones(nbits);
+ for (int i = 0; i < count ; i++) {
+ result <<= nbits;
+ result |= (bits & mask);
+ }
+ return result;
+}
+
+// this function writes the supplied bimm reference and returns a
+// boolean to indicate success (1) or fail (0) because an illegal
+// encoding must be treated as an UNALLOC instruction
+
+// construct a 32 bit immediate value for a logical immediate operation
+int expandLogicalImmediate(u_int32_t immN, u_int32_t immr,
+ u_int32_t imms, u_int64_t &bimm)
+{
+ int len; // ought to be <= 6
+ u_int32_t levels; // 6 bits
+ u_int32_t tmask_and; // 6 bits
+ u_int32_t wmask_and; // 6 bits
+ u_int32_t tmask_or; // 6 bits
+ u_int32_t wmask_or; // 6 bits
+ u_int64_t imm64; // 64 bits
+ u_int64_t tmask, wmask; // 64 bits
+ u_int32_t S, R, diff; // 6 bits?
+
+ if (immN == 1) {
+ len = 6; // looks like 7 given the spec above but this cannot be!
+ } else {
+ len = 0;
+ u_int32_t val = (~imms & 0x3f);
+ for (int i = 5; i > 0; i--) {
+ if (val & (1 << i)) {
+ len = i;
+ break;
+ }
+ }
+ if (len < 1) {
+ return 0;
+ }
+ // for valid inputs leading 1s in immr must be less than leading
+ // zeros in imms
+ int len2 = 0; // ought to be < len
+ u_int32_t val2 = (~immr & 0x3f);
+ for (int i = 5; i > 0; i--) {
+ if (!(val2 & (1 << i))) {
+ len2 = i;
+ break;
+ }
+ }
+ if (len2 >= len) {
+ return 0;
+ }
+ }
+
+ levels = (1 << len) - 1;
+
+ if ((imms & levels) == levels) {
+ return 0;
+ }
+
+ S = imms & levels;
+ R = immr & levels;
+
+ // 6 bit arithmetic!
+ diff = S - R;
+ tmask_and = (diff | ~levels) & 0x3f;
+ tmask_or = (diff & levels) & 0x3f;
+ tmask = 0xffffffffffffffffULL;
+
+ for (int i = 0; i < 6; i++) {
+ int nbits = 1 << i;
+ u_int64_t and_bit = pickbit(tmask_and, i);
+ u_int64_t or_bit = pickbit(tmask_or, i);
+ u_int64_t and_bits_sub = replicate(and_bit, 1, nbits);
+ u_int64_t or_bits_sub = replicate(or_bit, 1, nbits);
+ u_int64_t and_bits_top = (and_bits_sub << nbits) | ones(nbits);
+ u_int64_t or_bits_top = (0 << nbits) | or_bits_sub;
+
+ tmask = ((tmask
+ & (replicate(and_bits_top, 2 * nbits, 32 / nbits)))
+ | replicate(or_bits_top, 2 * nbits, 32 / nbits));
+ }
+
+ wmask_and = (immr | ~levels) & 0x3f;
+ wmask_or = (immr & levels) & 0x3f;
+
+ wmask = 0;
+
+ for (int i = 0; i < 6; i++) {
+ int nbits = 1 << i;
+ u_int64_t and_bit = pickbit(wmask_and, i);
+ u_int64_t or_bit = pickbit(wmask_or, i);
+ u_int64_t and_bits_sub = replicate(and_bit, 1, nbits);
+ u_int64_t or_bits_sub = replicate(or_bit, 1, nbits);
+ u_int64_t and_bits_top = (ones(nbits) << nbits) | and_bits_sub;
+ u_int64_t or_bits_top = (or_bits_sub << nbits) | 0;
+
+ wmask = ((wmask
+ & (replicate(and_bits_top, 2 * nbits, 32 / nbits)))
+ | replicate(or_bits_top, 2 * nbits, 32 / nbits));
+ }
+
+ if (diff & (1U << 6)) {
+ imm64 = tmask & wmask;
+ } else {
+ imm64 = tmask | wmask;
+ }
+
+
+ bimm = imm64;
+ return 1;
+}
+
+// constructor to initialise the lookup tables
+
+static void initLITables() __attribute__ ((constructor));
+static void initLITables()
+{
+ li_table_entry_count = 0;
+ for (unsigned index = 0; index < LI_TABLE_SIZE; index++) {
+ u_int32_t N = uimm(index, 12, 12);
+ u_int32_t immr = uimm(index, 11, 6);
+ u_int32_t imms = uimm(index, 5, 0);
+ if (expandLogicalImmediate(N, immr, imms, LITable[index])) {
+ InverseLITable[li_table_entry_count].immediate = LITable[index];
+ InverseLITable[li_table_entry_count].encoding = index;
+ li_table_entry_count++;
+ }
+ }
+ // now sort the inverse table
+ qsort(InverseLITable, li_table_entry_count,
+ sizeof(InverseLITable[0]), compare_immediate_pair);
+}
+
+// public APIs provided for logical immediate lookup and reverse lookup
+
+u_int64_t logical_immediate_for_encoding(u_int32_t encoding)
+{
+ return LITable[encoding];
+}
+
+u_int32_t encoding_for_logical_immediate(u_int64_t immediate)
+{
+ struct li_pair pair;
+ struct li_pair *result;
+
+ pair.immediate = immediate;
+
+ result = (struct li_pair *)
+ bsearch(&pair, InverseLITable, li_table_entry_count,
+ sizeof(InverseLITable[0]), compare_immediate_pair);
+
+ if (result) {
+ return result->encoding;
+ }
+
+ return 0xffffffff;
+}
+
+// floating point immediates are encoded in 8 bits
+// fpimm[7] = sign bit
+// fpimm[6:4] = signed exponent
+// fpimm[3:0] = fraction (assuming leading 1)
+// i.e. F = s * 1.f * 2^(e - b)
+
+u_int64_t fp_immediate_for_encoding(u_int32_t imm8, int is_dp)
+{
+ union {
+ float fpval;
+ double dpval;
+ u_int64_t val;
+ };
+
+ u_int32_t s, e, f;
+ s = (imm8 >> 7 ) & 0x1;
+ e = (imm8 >> 4) & 0x7;
+ f = imm8 & 0xf;
+ // the fp value is s * n/16 * 2r where n is 16+e
+ fpval = (16.0 + f) / 16.0;
+ // n.b. exponent is signed
+ if (e < 4) {
+ int epos = e;
+ for (int i = 0; i <= epos; i++) {
+ fpval *= 2.0;
+ }
+ } else {
+ int eneg = 7 - e;
+ for (int i = 0; i < eneg; i++) {
+ fpval /= 2.0;
+ }
+ }
+
+ if (s) {
+ fpval = -fpval;
+ }
+ if (is_dp) {
+ dpval = (double)fpval;
+ }
+ return val;
+}
+
+u_int32_t encoding_for_fp_immediate(float immediate)
+{
+ // given a float which is of the form
+ //
+ // s * n/16 * 2r
+ //
+ // where n is 16+f and imm1:s, imm4:f, simm3:r
+ // return the imm8 result [s:r:f]
+ //
+
+ union {
+ float fpval;
+ u_int32_t val;
+ };
+ fpval = immediate;
+ u_int32_t s, r, f, res;
+ // sign bit is 31
+ s = (val >> 31) & 0x1;
+ // exponent is bits 30-23 but we only want the bottom 3 bits
+ // strictly we ought to check that the bits bits 30-25 are
+ // either all 1s or all 0s
+ r = (val >> 23) & 0x7;
+ // fraction is bits 22-0
+ f = (val >> 19) & 0xf;
+ res = (s << 7) | (r << 4) | f;
+ return res;
+}
+