2) Speculative prefetching. If we are able to determine that the difference
between addresses accessed by a memory reference is usually constant, we
may add the prefetch instructions.
+ FIXME: This transformation was removed together with RTL based value
+ profiling.
Every such optimization should add its requirements for profiled values to
insn_values_to_profile function. This function is called from branch_prob
compilation with -fprofile-arcs. The optimization may then read the
gathered data in the second compilation with -fbranch-probabilities.
- There are currently two versions, RTL-based and tree-based. Over time
- the RTL-based version may go away.
-
- In the RTL-based version, the measured data is appended as REG_VALUE_PROFILE
- note to the instrumented insn. The argument to the note consists of an
- EXPR_LIST where its members have the following meaning (from the first to
- the last):
-
- -- type of information gathered (HIST_TYPE*)
- -- the expression that is profiled
- -- list of counters starting from the first one.
-
- In the tree-based version, the measured data is pointed to from the histograms
+ The measured data is pointed to from the histograms
field of the statement annotation of the instrumented insns. It is
kept as a linked list of struct histogram_value_t's, which contain the
same information as above. */
-/* For speculative prefetching, the range in that we do not prefetch (because
- we assume that it will be in cache anyway). The asymmetry between min and
- max range is trying to reflect the fact that the sequential prefetching
- of the data is commonly done directly by hardware. Nevertheless, these
- values are just a guess and should of course be target-specific.
-
- FIXME: There is no tree form of speculative prefetching as yet.
-
- FIXME: A better approach to instrumentation in the profile-generation
- pass is to generate calls to magic library functions (to be added to
- libgcc) rather than inline code. This approach will probably be
- necessary to get tree-based speculative prefetching working in a useful
- fashion, as inline code bloats things so much the rest of the compiler has
- serious problems dealing with it (judging from the rtl behavior). */
-
-#ifndef NOPREFETCH_RANGE_MIN
-#define NOPREFETCH_RANGE_MIN (-16)
-#endif
-#ifndef NOPREFETCH_RANGE_MAX
-#define NOPREFETCH_RANGE_MAX 32
-#endif
-
-static void rtl_divmod_values_to_profile (rtx, histogram_values *);
-#ifdef HAVE_prefetch
-static bool insn_prefetch_values_to_profile (rtx, histogram_values *);
-static int find_mem_reference_1 (rtx *, void *);
-static void find_mem_reference_2 (rtx, rtx, void *);
-static bool find_mem_reference (rtx, rtx *, int *);
-#endif
-
-static void rtl_values_to_profile (rtx, histogram_values *);
-static rtx rtl_divmod_fixed_value (enum machine_mode, enum rtx_code, rtx, rtx,
- rtx, gcov_type, int);
-static rtx rtl_mod_pow2 (enum machine_mode, enum rtx_code, rtx, rtx, rtx, int);
-static rtx rtl_mod_subtract (enum machine_mode, enum rtx_code, rtx, rtx, rtx,
- int, int, int);
-#ifdef HAVE_prefetch
-static rtx gen_speculative_prefetch (rtx, gcov_type, int);
-#endif
-static bool rtl_divmod_fixed_value_transform (rtx);
-static bool rtl_mod_pow2_value_transform (rtx);
-static bool rtl_mod_subtract_transform (rtx);
-#ifdef HAVE_prefetch
-static bool speculative_prefetching_transform (rtx);
-#endif
+
static tree tree_divmod_fixed_value (tree, tree, tree, tree,
tree, int, gcov_type, gcov_type);
static tree tree_mod_pow2 (tree, tree, tree, tree, int, gcov_type, gcov_type);
static bool tree_mod_pow2_value_transform (tree);
static bool tree_mod_subtract_transform (tree);
-\f
-/* Find values inside INSN for that we want to measure histograms for
- division/modulo optimization and stores them to VALUES. */
-static void
-rtl_divmod_values_to_profile (rtx insn, histogram_values *values)
-{
- rtx set, set_src, op1, op2;
- enum machine_mode mode;
- histogram_value hist;
-
- if (!INSN_P (insn))
- return;
-
- set = single_set (insn);
- if (!set)
- return;
-
- mode = GET_MODE (SET_DEST (set));
- if (!INTEGRAL_MODE_P (mode))
- return;
-
- set_src = SET_SRC (set);
- switch (GET_CODE (set_src))
- {
- case DIV:
- case MOD:
- case UDIV:
- case UMOD:
- op1 = XEXP (set_src, 0);
- op2 = XEXP (set_src, 1);
- if (side_effects_p (op2))
- return;
-
- /* Check for a special case where the divisor is power of 2. */
- if ((GET_CODE (set_src) == UMOD) && !CONSTANT_P (op2))
- {
- hist = ggc_alloc (sizeof (*hist));
- hist->hvalue.rtl.value = op2;
- hist->hvalue.rtl.seq = NULL_RTX;
- hist->hvalue.rtl.mode = mode;
- hist->hvalue.rtl.insn = insn;
- hist->type = HIST_TYPE_POW2;
- VEC_safe_push (histogram_value, heap, *values, hist);
- }
-
- /* Check whether the divisor is not in fact a constant. */
- if (!CONSTANT_P (op2))
- {
- hist = ggc_alloc (sizeof (*hist));
- hist->hvalue.rtl.value = op2;
- hist->hvalue.rtl.mode = mode;
- hist->hvalue.rtl.seq = NULL_RTX;
- hist->hvalue.rtl.insn = insn;
- hist->type = HIST_TYPE_SINGLE_VALUE;
- VEC_safe_push (histogram_value, heap, *values, hist);
- }
-
- /* For mod, check whether it is not often a noop (or replaceable by
- a few subtractions). */
- if (GET_CODE (set_src) == UMOD && !side_effects_p (op1))
- {
- rtx tmp;
-
- hist = ggc_alloc (sizeof (*hist));
- start_sequence ();
- tmp = simplify_gen_binary (DIV, mode, copy_rtx (op1), copy_rtx (op2));
- hist->hvalue.rtl.value = force_operand (tmp, NULL_RTX);
- hist->hvalue.rtl.seq = get_insns ();
- end_sequence ();
- hist->hvalue.rtl.mode = mode;
- hist->hvalue.rtl.insn = insn;
- hist->type = HIST_TYPE_INTERVAL;
- hist->hdata.intvl.int_start = 0;
- hist->hdata.intvl.steps = 2;
- VEC_safe_push (histogram_value, heap, *values, hist);
- }
- return;
-
- default:
- return;
- }
-}
-
-#ifdef HAVE_prefetch
-
-/* Called from find_mem_reference through for_each_rtx, finds a memory
- reference. I.e. if *EXPR is a MEM, the reference to this MEM is stored
- to *RET and the traversing of the expression is interrupted by returning 1.
- Otherwise 0 is returned. */
-
-static int
-find_mem_reference_1 (rtx *expr, void *ret)
-{
- rtx *mem = ret;
-
- if (MEM_P (*expr))
- {
- *mem = *expr;
- return 1;
- }
- return 0;
-}
-
-/* Called form find_mem_reference through note_stores to find out whether
- the memory reference MEM is a store. I.e. if EXPR == MEM, the variable
- FMR2_WRITE is set to true. */
-
-static int fmr2_write;
-static void
-find_mem_reference_2 (rtx expr, rtx pat ATTRIBUTE_UNUSED, void *mem)
-{
- if (expr == mem)
- fmr2_write = true;
-}
-
-/* Find a memory reference inside INSN, return it in MEM. Set WRITE to true
- if it is a write of the mem. Return false if no memory reference is found,
- true otherwise. */
-
-static bool
-find_mem_reference (rtx insn, rtx *mem, int *write)
-{
- *mem = NULL_RTX;
- for_each_rtx (&PATTERN (insn), find_mem_reference_1, mem);
-
- if (!*mem)
- return false;
-
- fmr2_write = false;
- note_stores (PATTERN (insn), find_mem_reference_2, *mem);
- *write = fmr2_write;
- return true;
-}
-
-/* Find values inside INSN for that we want to measure histograms for
- a speculative prefetching. Add them to the list VALUES.
- Returns true if such we found any such value, false otherwise. */
-
-static bool
-insn_prefetch_values_to_profile (rtx insn, histogram_values* values)
-{
- rtx mem, address;
- int write;
- histogram_value hist;
-
- /* It only makes sense to look for memory references in ordinary insns. */
- if (!NONJUMP_INSN_P (insn))
- return false;
-
- if (!find_mem_reference (insn, &mem, &write))
- return false;
-
- address = XEXP (mem, 0);
- if (side_effects_p (address))
- return false;
-
- if (CONSTANT_P (address))
- return false;
-
- hist = ggc_alloc (sizeof (*hist));
- hist->hvalue.rtl.value = address;
- hist->hvalue.rtl.mode = GET_MODE (address);
- hist->hvalue.rtl.seq = NULL_RTX;
- hist->hvalue.rtl.insn = insn;
- hist->type = HIST_TYPE_CONST_DELTA;
- VEC_safe_push (histogram_value, heap, *values, hist);
-
- return true;
-}
-#endif
-/* Find values inside INSN for that we want to measure histograms and adds
- them to list VALUES (increasing the record of its length in N_VALUES). */
-static void
-rtl_values_to_profile (rtx insn, histogram_values *values)
-{
- if (flag_value_profile_transformations)
- rtl_divmod_values_to_profile (insn, values);
-
-#ifdef HAVE_prefetch
- if (flag_speculative_prefetching)
- insn_prefetch_values_to_profile (insn, values);
-#endif
-}
-
-/* Find list of values for that we want to measure histograms. */
-static void
-rtl_find_values_to_profile (histogram_values *values)
-{
- rtx insn;
- unsigned i, libcall_level;
- histogram_value hist;
-
- life_analysis (NULL, PROP_DEATH_NOTES);
-
- *values = NULL;
- libcall_level = 0;
- for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
- rtl_values_to_profile (insn, values);
- static_values = *values;
-
- for (i = 0; VEC_iterate (histogram_value, *values, i, hist); i++)
- {
- switch (hist->type)
- {
- case HIST_TYPE_INTERVAL:
- if (dump_file)
- fprintf (dump_file,
- "Interval counter for insn %d, range %d -- %d.\n",
- INSN_UID ((rtx)hist->hvalue.rtl.insn),
- hist->hdata.intvl.int_start,
- (hist->hdata.intvl.int_start
- + hist->hdata.intvl.steps - 1));
- hist->n_counters = hist->hdata.intvl.steps + 2;
- break;
-
- case HIST_TYPE_POW2:
- if (dump_file)
- fprintf (dump_file,
- "Pow2 counter for insn %d.\n",
- INSN_UID ((rtx)hist->hvalue.rtl.insn));
- hist->n_counters = 2;
- break;
-
- case HIST_TYPE_SINGLE_VALUE:
- if (dump_file)
- fprintf (dump_file,
- "Single value counter for insn %d.\n",
- INSN_UID ((rtx)hist->hvalue.rtl.insn));
- hist->n_counters = 3;
- break;
-
- case HIST_TYPE_CONST_DELTA:
- if (dump_file)
- fprintf (dump_file,
- "Constant delta counter for insn %d.\n",
- INSN_UID ((rtx)hist->hvalue.rtl.insn));
- hist->n_counters = 4;
- break;
-
- default:
- gcc_unreachable ();
- }
- }
- allocate_reg_info (max_reg_num (), FALSE, FALSE);
-}
-
-/* Main entry point. Finds REG_VALUE_PROFILE notes from profiler and uses
- them to identify and exploit properties of values that are hard to analyze
- statically.
-
- We do following transformations:
-
- 1)
-
- x = a / b;
-
- where b is almost always a constant N is transformed to
-
- if (b == N)
- x = a / N;
- else
- x = a / b;
-
- Analogically with %
-
- 2)
-
- x = a % b
-
- where b is almost always a power of 2 and the division is unsigned
- TODO -- handle signed case as well
-
- if ((b & (b - 1)) == 0)
- x = a & (b - 1);
- else
- x = x % b;
-
- Note that when b = 0, no error will occur and x = a; this is correct,
- as result of such operation is undefined.
-
- 3)
-
- x = a % b
-
- where a is almost always less then b and the division is unsigned
- TODO -- handle signed case as well
-
- x = a;
- if (x >= b)
- x %= b;
-
- 4)
-
- x = a % b
-
- where a is almost always less then 2 * b and the division is unsigned
- TODO -- handle signed case as well
-
- x = a;
- if (x >= b)
- x -= b;
- if (x >= b)
- x %= b;
-
- It would be possible to continue analogically for K * b for other small
- K's, but it is probably not useful.
-
- 5)
-
- Read or write of mem[address], where the value of address changes usually
- by a constant C != 0 between the following accesses to the computation; with
- -fspeculative-prefetching we then add a prefetch of address + C before
- the insn. This handles prefetching of several interesting cases in addition
- to a simple prefetching for addresses that are induction variables, e. g.
- linked lists allocated sequentially (even in case they are processed
- recursively).
-
- TODO -- we should also check whether there is not (usually) a small
- difference with the adjacent memory references, so that we do
- not issue overlapping prefetches. Also we should employ some
- heuristics to eliminate cases where prefetching evidently spoils
- the code.
- -- it should somehow cooperate with the loop optimizer prefetching
-
- TODO:
-
- There are other useful cases that could be handled by a similar mechanism,
- for example:
-
- for (i = 0; i < n; i++)
- ...
-
- transform to (for constant N):
-
- if (n == N)
- for (i = 0; i < N; i++)
- ...
- else
- for (i = 0; i < n; i++)
- ...
- making unroller happy. Since this may grow the code significantly,
- we would have to be very careful here. */
-
-static bool
-rtl_value_profile_transformations (void)
-{
- rtx insn, next;
- int changed = false;
-
- for (insn = get_insns (); insn; insn = next)
- {
- next = NEXT_INSN (insn);
-
- if (!INSN_P (insn))
- continue;
-
- /* Scan for insn carrying a histogram. */
- if (!find_reg_note (insn, REG_VALUE_PROFILE, 0))
- continue;
-
- /* Ignore cold areas -- we are growing a code. */
- if (!maybe_hot_bb_p (BLOCK_FOR_INSN (insn)))
- continue;
-
- if (dump_file)
- {
- fprintf (dump_file, "Trying transformations on insn %d\n",
- INSN_UID (insn));
- print_rtl_single (dump_file, insn);
- }
-
- /* Transformations: */
- if (flag_value_profile_transformations
- && (rtl_mod_subtract_transform (insn)
- || rtl_divmod_fixed_value_transform (insn)
- || rtl_mod_pow2_value_transform (insn)))
- changed = true;
-#ifdef HAVE_prefetch
- if (flag_speculative_prefetching
- && speculative_prefetching_transform (insn))
- changed = true;
-#endif
- }
-
- if (changed)
- {
- commit_edge_insertions ();
- allocate_reg_info (max_reg_num (), FALSE, FALSE);
- }
-
- return changed;
-}
-
-/* Generate code for transformation 1 (with MODE and OPERATION, operands OP1
- and OP2, whose value is expected to be VALUE, result TARGET and
- probability of taking the optimal path PROB). */
-static rtx
-rtl_divmod_fixed_value (enum machine_mode mode, enum rtx_code operation,
- rtx target, rtx op1, rtx op2, gcov_type value,
- int prob)
-{
- rtx tmp, tmp1, jump;
- rtx neq_label = gen_label_rtx ();
- rtx end_label = gen_label_rtx ();
- rtx sequence;
-
- start_sequence ();
-
- if (!REG_P (op2))
- {
- tmp = gen_reg_rtx (mode);
- emit_move_insn (tmp, copy_rtx (op2));
- }
- else
- tmp = op2;
-
- do_compare_rtx_and_jump (tmp, GEN_INT (value), NE, 0, mode, NULL_RTX,
- NULL_RTX, neq_label);
-
- /* Add branch probability to jump we just created. */
- jump = get_last_insn ();
- REG_NOTES (jump) = gen_rtx_EXPR_LIST (REG_BR_PROB,
- GEN_INT (REG_BR_PROB_BASE - prob),
- REG_NOTES (jump));
-
- tmp1 = simplify_gen_binary (operation, mode,
- copy_rtx (op1), GEN_INT (value));
- tmp1 = force_operand (tmp1, target);
- if (tmp1 != target)
- emit_move_insn (copy_rtx (target), copy_rtx (tmp1));
-
- emit_jump_insn (gen_jump (end_label));
- emit_barrier ();
-
- emit_label (neq_label);
- tmp1 = simplify_gen_binary (operation, mode,
- copy_rtx (op1), copy_rtx (tmp));
- tmp1 = force_operand (tmp1, target);
- if (tmp1 != target)
- emit_move_insn (copy_rtx (target), copy_rtx (tmp1));
-
- emit_label (end_label);
-
- sequence = get_insns ();
- end_sequence ();
- rebuild_jump_labels (sequence);
- return sequence;
-}
-
-/* Do transform 1) on INSN if applicable. */
-static bool
-rtl_divmod_fixed_value_transform (rtx insn)
-{
- rtx set, set_src, set_dest, op1, op2, value, histogram;
- enum rtx_code code;
- enum machine_mode mode;
- gcov_type val, count, all;
- edge e;
- int prob;
-
- set = single_set (insn);
- if (!set)
- return false;
-
- set_src = SET_SRC (set);
- set_dest = SET_DEST (set);
- code = GET_CODE (set_src);
- mode = GET_MODE (set_dest);
-
- if (code != DIV && code != MOD && code != UDIV && code != UMOD)
- return false;
- op1 = XEXP (set_src, false);
- op2 = XEXP (set_src, 1);
-
- for (histogram = REG_NOTES (insn);
- histogram;
- histogram = XEXP (histogram, 1))
- if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
- && XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_SINGLE_VALUE))
- break;
-
- if (!histogram)
- return false;
-
- histogram = XEXP (XEXP (histogram, 0), 1);
- value = XEXP (histogram, 0);
- histogram = XEXP (histogram, 1);
- val = INTVAL (XEXP (histogram, 0));
- histogram = XEXP (histogram, 1);
- count = INTVAL (XEXP (histogram, 0));
- histogram = XEXP (histogram, 1);
- all = INTVAL (XEXP (histogram, 0));
-
- /* We require that count be at least half of all; this means
- that for the transformation to fire the value must be constant
- at least 50% of time (and 75% gives the guarantee of usage). */
- if (!rtx_equal_p (op2, value) || 2 * count < all)
- return false;
-
- if (dump_file)
- fprintf (dump_file, "Div/mod by constant transformation on insn %d\n",
- INSN_UID (insn));
-
- /* Compute probability of taking the optimal path. */
- prob = (count * REG_BR_PROB_BASE + all / 2) / all;
-
- e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
- delete_insn (insn);
-
- insert_insn_on_edge (
- rtl_divmod_fixed_value (mode, code, set_dest,
- op1, op2, val, prob), e);
-
- return true;
-}
-
-/* Generate code for transformation 2 (with MODE and OPERATION, operands OP1
- and OP2, result TARGET and probability of taking the optimal path PROB). */
-static rtx
-rtl_mod_pow2 (enum machine_mode mode, enum rtx_code operation, rtx target,
- rtx op1, rtx op2, int prob)
-{
- rtx tmp, tmp1, tmp2, tmp3, jump;
- rtx neq_label = gen_label_rtx ();
- rtx end_label = gen_label_rtx ();
- rtx sequence;
-
- start_sequence ();
-
- if (!REG_P (op2))
- {
- tmp = gen_reg_rtx (mode);
- emit_move_insn (tmp, copy_rtx (op2));
- }
- else
- tmp = op2;
-
- tmp1 = expand_simple_binop (mode, PLUS, tmp, constm1_rtx, NULL_RTX,
- 0, OPTAB_WIDEN);
- tmp2 = expand_simple_binop (mode, AND, tmp, tmp1, NULL_RTX,
- 0, OPTAB_WIDEN);
- do_compare_rtx_and_jump (tmp2, const0_rtx, NE, 0, mode, NULL_RTX,
- NULL_RTX, neq_label);
-
- /* Add branch probability to jump we just created. */
- jump = get_last_insn ();
- REG_NOTES (jump) = gen_rtx_EXPR_LIST (REG_BR_PROB,
- GEN_INT (REG_BR_PROB_BASE - prob),
- REG_NOTES (jump));
-
- tmp3 = expand_simple_binop (mode, AND, op1, tmp1, target,
- 0, OPTAB_WIDEN);
- if (tmp3 != target)
- emit_move_insn (copy_rtx (target), tmp3);
- emit_jump_insn (gen_jump (end_label));
- emit_barrier ();
-
- emit_label (neq_label);
- tmp1 = simplify_gen_binary (operation, mode, copy_rtx (op1), copy_rtx (tmp));
- tmp1 = force_operand (tmp1, target);
- if (tmp1 != target)
- emit_move_insn (target, tmp1);
-
- emit_label (end_label);
-
- sequence = get_insns ();
- end_sequence ();
- rebuild_jump_labels (sequence);
- return sequence;
-}
-
-/* Do transform 2) on INSN if applicable. */
-static bool
-rtl_mod_pow2_value_transform (rtx insn)
-{
- rtx set, set_src, set_dest, op1, op2, value, histogram;
- enum rtx_code code;
- enum machine_mode mode;
- gcov_type wrong_values, count;
- edge e;
- int all, prob;
-
- set = single_set (insn);
- if (!set)
- return false;
-
- set_src = SET_SRC (set);
- set_dest = SET_DEST (set);
- code = GET_CODE (set_src);
- mode = GET_MODE (set_dest);
-
- if (code != UMOD)
- return false;
- op1 = XEXP (set_src, 0);
- op2 = XEXP (set_src, 1);
-
- for (histogram = REG_NOTES (insn);
- histogram;
- histogram = XEXP (histogram, 1))
- if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
- && XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_POW2))
- break;
-
- if (!histogram)
- return false;
-
- histogram = XEXP (XEXP (histogram, 0), 1);
- value = XEXP (histogram, 0);
- histogram = XEXP (histogram, 1);
- wrong_values = INTVAL (XEXP (histogram, 0));
- histogram = XEXP (histogram, 1);
- count = INTVAL (XEXP (histogram, 0));
-
- if (!rtx_equal_p (op2, value))
- return false;
-
- /* We require that we hit a power of two at least half of all evaluations. */
- if (count < wrong_values)
- return false;
-
- if (dump_file)
- fprintf (dump_file, "Mod power of 2 transformation on insn %d\n",
- INSN_UID (insn));
-
- /* Compute probability of taking the optimal path. */
- all = count + wrong_values;
- prob = (count * REG_BR_PROB_BASE + all / 2) / all;
-
- e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
- delete_insn (insn);
-
- insert_insn_on_edge (
- rtl_mod_pow2 (mode, code, set_dest, op1, op2, prob), e);
-
- return true;
-}
-
-/* Generate code for transformations 3 and 4 (with MODE and OPERATION,
- operands OP1 and OP2, result TARGET, at most SUB subtractions, and
- probability of taking the optimal path(s) PROB1 and PROB2). */
-static rtx
-rtl_mod_subtract (enum machine_mode mode, enum rtx_code operation,
- rtx target, rtx op1, rtx op2, int sub, int prob1, int prob2)
-{
- rtx tmp, tmp1, jump;
- rtx end_label = gen_label_rtx ();
- rtx sequence;
- int i;
-
- start_sequence ();
-
- if (!REG_P (op2))
- {
- tmp = gen_reg_rtx (mode);
- emit_move_insn (tmp, copy_rtx (op2));
- }
- else
- tmp = op2;
-
- emit_move_insn (target, copy_rtx (op1));
- do_compare_rtx_and_jump (target, tmp, LTU, 0, mode, NULL_RTX,
- NULL_RTX, end_label);
-
- /* Add branch probability to jump we just created. */
- jump = get_last_insn ();
- REG_NOTES (jump) = gen_rtx_EXPR_LIST (REG_BR_PROB,
- GEN_INT (prob1), REG_NOTES (jump));
-
- for (i = 0; i < sub; i++)
- {
- tmp1 = expand_simple_binop (mode, MINUS, target, tmp, target,
- 0, OPTAB_WIDEN);
- if (tmp1 != target)
- emit_move_insn (target, tmp1);
- do_compare_rtx_and_jump (target, tmp, LTU, 0, mode, NULL_RTX,
- NULL_RTX, end_label);
-
- /* Add branch probability to jump we just created. */
- jump = get_last_insn ();
- REG_NOTES (jump) = gen_rtx_EXPR_LIST (REG_BR_PROB,
- GEN_INT (prob2), REG_NOTES (jump));
- }
-
- tmp1 = simplify_gen_binary (operation, mode, copy_rtx (target), copy_rtx (tmp));
- tmp1 = force_operand (tmp1, target);
- if (tmp1 != target)
- emit_move_insn (target, tmp1);
-
- emit_label (end_label);
-
- sequence = get_insns ();
- end_sequence ();
- rebuild_jump_labels (sequence);
- return sequence;
-}
-
-/* Do transforms 3) and 4) on INSN if applicable. */
-static bool
-rtl_mod_subtract_transform (rtx insn)
-{
- rtx set, set_src, set_dest, op1, op2, histogram;
- enum rtx_code code;
- enum machine_mode mode;
- gcov_type wrong_values, counts[2], count, all;
- edge e;
- int i, prob1, prob2;
-
- set = single_set (insn);
- if (!set)
- return false;
-
- set_src = SET_SRC (set);
- set_dest = SET_DEST (set);
- code = GET_CODE (set_src);
- mode = GET_MODE (set_dest);
-
- if (code != UMOD)
- return false;
- op1 = XEXP (set_src, 0);
- op2 = XEXP (set_src, 1);
-
- for (histogram = REG_NOTES (insn);
- histogram;
- histogram = XEXP (histogram, 1))
- if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
- && XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_INTERVAL))
- break;
-
- if (!histogram)
- return false;
-
- histogram = XEXP (XEXP (histogram, 0), 1);
- histogram = XEXP (histogram, 1);
-
- all = 0;
- for (i = 0; i < 2; i++)
- {
- counts[i] = INTVAL (XEXP (histogram, 0));
- all += counts[i];
- histogram = XEXP (histogram, 1);
- }
- wrong_values = INTVAL (XEXP (histogram, 0));
- histogram = XEXP (histogram, 1);
- wrong_values += INTVAL (XEXP (histogram, 0));
- all += wrong_values;
-
- /* We require that we use just subtractions in at least 50% of all
- evaluations. */
- count = 0;
- for (i = 0; i < 2; i++)
- {
- count += counts[i];
- if (count * 2 >= all)
- break;
- }
-
- if (i == 2)
- return false;
-
- if (dump_file)
- fprintf (dump_file, "Mod subtract transformation on insn %d\n",
- INSN_UID (insn));
-
- /* Compute probability of taking the optimal path(s). */
- prob1 = (counts[0] * REG_BR_PROB_BASE + all / 2) / all;
- prob2 = (counts[1] * REG_BR_PROB_BASE + all / 2) / all;
-
- e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
- delete_insn (insn);
-
- insert_insn_on_edge (
- rtl_mod_subtract (mode, code, set_dest,
- op1, op2, i, prob1, prob2), e);
-
- return true;
-}
-
-#ifdef HAVE_prefetch
-/* Generate code for transformation 5 for mem with ADDRESS and a constant
- step DELTA. WRITE is true if the reference is a store to mem. */
-
-static rtx
-gen_speculative_prefetch (rtx address, gcov_type delta, int write)
-{
- rtx tmp;
- rtx sequence;
-
- /* TODO: we do the prefetching for just one iteration ahead, which
- often is not enough. */
- start_sequence ();
- if (offsettable_address_p (0, VOIDmode, address))
- tmp = plus_constant (copy_rtx (address), delta);
- else
- {
- tmp = simplify_gen_binary (PLUS, Pmode,
- copy_rtx (address), GEN_INT (delta));
- tmp = force_operand (tmp, NULL);
- }
- if (! (*insn_data[(int)CODE_FOR_prefetch].operand[0].predicate)
- (tmp, insn_data[(int)CODE_FOR_prefetch].operand[0].mode))
- tmp = force_reg (Pmode, tmp);
- emit_insn (gen_prefetch (tmp, GEN_INT (write), GEN_INT (3)));
- sequence = get_insns ();
- end_sequence ();
-
- return sequence;
-}
-
-/* Do transform 5) on INSN if applicable. */
-
-static bool
-speculative_prefetching_transform (rtx insn)
-{
- rtx histogram, value;
- gcov_type val, count, all;
- edge e;
- rtx mem, address;
- int write;
-
- if (!maybe_hot_bb_p (BLOCK_FOR_INSN (insn)))
- return false;
-
- if (!find_mem_reference (insn, &mem, &write))
- return false;
-
- address = XEXP (mem, 0);
- if (side_effects_p (address))
- return false;
-
- if (CONSTANT_P (address))
- return false;
-
- for (histogram = REG_NOTES (insn);
- histogram;
- histogram = XEXP (histogram, 1))
- if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
- && XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_CONST_DELTA))
- break;
-
- if (!histogram)
- return false;
-
- histogram = XEXP (XEXP (histogram, 0), 1);
- value = XEXP (histogram, 0);
- histogram = XEXP (histogram, 1);
- /* Skip last value referenced. */
- histogram = XEXP (histogram, 1);
- val = INTVAL (XEXP (histogram, 0));
- histogram = XEXP (histogram, 1);
- count = INTVAL (XEXP (histogram, 0));
- histogram = XEXP (histogram, 1);
- all = INTVAL (XEXP (histogram, 0));
-
- /* With that few executions we do not really have a reason to optimize the
- statement, and more importantly, the data about differences of addresses
- are spoiled by the first item that had no previous value to compare
- with. */
- if (all < 4)
- return false;
-
- /* We require that count be at least half of all; this means
- that for the transformation to fire the value must be constant
- at least 50% of time (and 75% gives the guarantee of usage). */
- if (!rtx_equal_p (address, value) || 2 * count < all)
- return false;
-
- /* If the difference is too small, it does not make too much sense to
- prefetch, as the memory is probably already in cache. */
- if (val >= NOPREFETCH_RANGE_MIN && val <= NOPREFETCH_RANGE_MAX)
- return false;
-
- if (dump_file)
- fprintf (dump_file, "Speculative prefetching for insn %d\n",
- INSN_UID (insn));
-
- e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
-
- insert_insn_on_edge (gen_speculative_prefetch (address, val, write), e);
-
- return true;
-}
-#endif /* HAVE_prefetch */
-
/* Tree based transformations. */
static bool
tree_value_profile_transformations (void)
/* Free extra storage from compute_value_histograms. */
while (th)
{
- free (th->hvalue.tree.counters);
- th = th->hvalue.tree.next;
+ free (th->hvalue.counters);
+ th = th->hvalue.next;
}
ann->histograms = 0;
}
if (!ann->histograms)
return false;
- for (histogram = ann->histograms; histogram; histogram = histogram->hvalue.tree.next)
+ for (histogram = ann->histograms; histogram; histogram = histogram->hvalue.next)
if (histogram->type == HIST_TYPE_SINGLE_VALUE)
break;
if (!histogram)
return false;
- value = histogram->hvalue.tree.value;
- val = histogram->hvalue.tree.counters[0];
- count = histogram->hvalue.tree.counters[1];
- all = histogram->hvalue.tree.counters[2];
+ value = histogram->hvalue.value;
+ val = histogram->hvalue.counters[0];
+ count = histogram->hvalue.counters[1];
+ all = histogram->hvalue.counters[2];
/* We require that count is at least half of all; this means
that for the transformation to fire the value must be constant
if (!ann->histograms)
return false;
- for (histogram = ann->histograms; histogram; histogram = histogram->hvalue.tree.next)
+ for (histogram = ann->histograms; histogram; histogram = histogram->hvalue.next)
if (histogram->type == HIST_TYPE_POW2)
break;
if (!histogram)
return false;
- value = histogram->hvalue.tree.value;
- wrong_values = histogram->hvalue.tree.counters[0];
- count = histogram->hvalue.tree.counters[1];
+ value = histogram->hvalue.value;
+ wrong_values = histogram->hvalue.counters[0];
+ count = histogram->hvalue.counters[1];
/* We require that we hit a power of 2 at least half of all evaluations. */
if (simple_cst_equal (op2, value) != 1 || count < wrong_values)
if (!ann->histograms)
return false;
- for (histogram = ann->histograms; histogram; histogram = histogram->hvalue.tree.next)
+ for (histogram = ann->histograms; histogram; histogram = histogram->hvalue.next)
if (histogram->type == HIST_TYPE_INTERVAL)
break;
if (!histogram)
return false;
- value = histogram->hvalue.tree.value;
+ value = histogram->hvalue.value;
all = 0;
wrong_values = 0;
for (i = 0; i < histogram->hdata.intvl.steps; i++)
- all += histogram->hvalue.tree.counters[i];
+ all += histogram->hvalue.counters[i];
- wrong_values += histogram->hvalue.tree.counters[i];
- wrong_values += histogram->hvalue.tree.counters[i+1];
+ wrong_values += histogram->hvalue.counters[i];
+ wrong_values += histogram->hvalue.counters[i+1];
all += wrong_values;
/* We require that we use just subtractions in at least 50% of all
count = 0;
for (i = 0; i < histogram->hdata.intvl.steps; i++)
{
- count += histogram->hvalue.tree.counters[i];
+ count += histogram->hvalue.counters[i];
if (count * 2 >= all)
break;
}
}
/* Compute probability of taking the optimal path(s). */
- prob1 = (histogram->hvalue.tree.counters[0] * REG_BR_PROB_BASE + all / 2) / all;
- prob2 = (histogram->hvalue.tree.counters[1] * REG_BR_PROB_BASE + all / 2) / all;
+ prob1 = (histogram->hvalue.counters[0] * REG_BR_PROB_BASE + all / 2) / all;
+ prob2 = (histogram->hvalue.counters[1] * REG_BR_PROB_BASE + all / 2) / all;
/* In practice, "steps" is always 2. This interface reflects this,
and will need to be changed if "steps" can change. */
result = tree_mod_subtract (stmt, op, op1, op2, prob1, prob2, i,
- histogram->hvalue.tree.counters[0],
- histogram->hvalue.tree.counters[1], all);
+ histogram->hvalue.counters[0],
+ histogram->hvalue.counters[1], all);
TREE_OPERAND (modify, 1) = result;
return true;
}
-\f
-/* Connection to the outside world. */
-/* Struct for IR-dependent hooks. */
+
struct value_prof_hooks {
/* Find list of values for which we want to measure histograms. */
void (*find_values_to_profile) (histogram_values *);
statically. See value-prof.c for more detail. */
bool (*value_profile_transformations) (void);
};
-
-/* Hooks for RTL-based versions (the only ones that currently work). */
-static struct value_prof_hooks rtl_value_prof_hooks =
-{
- rtl_find_values_to_profile,
- rtl_value_profile_transformations
-};
-
-void
-rtl_register_value_prof_hooks (void)
-{
- value_prof_hooks = &rtl_value_prof_hooks;
- gcc_assert (!ir_type ());
-}
\f
/* Find values inside STMT for that we want to measure histograms for
division/modulo optimization. */
/* Check for the case where the divisor is the same value most
of the time. */
hist = ggc_alloc (sizeof (*hist));
- hist->hvalue.tree.value = divisor;
- hist->hvalue.tree.stmt = stmt;
+ hist->hvalue.value = divisor;
+ hist->hvalue.stmt = stmt;
hist->type = HIST_TYPE_SINGLE_VALUE;
VEC_quick_push (histogram_value, *values, hist);
}
{
/* Check for a special case where the divisor is power of 2. */
hist = ggc_alloc (sizeof (*hist));
- hist->hvalue.tree.value = divisor;
- hist->hvalue.tree.stmt = stmt;
+ hist->hvalue.value = divisor;
+ hist->hvalue.stmt = stmt;
hist->type = HIST_TYPE_POW2;
VEC_quick_push (histogram_value, *values, hist);
hist = ggc_alloc (sizeof (*hist));
- hist->hvalue.tree.stmt = stmt;
- hist->hvalue.tree.value
+ hist->hvalue.stmt = stmt;
+ hist->hvalue.value
= build2 (TRUNC_DIV_EXPR, type, op0, divisor);
hist->type = HIST_TYPE_INTERVAL;
hist->hdata.intvl.int_start = 0;
if (dump_file)
{
fprintf (dump_file, "Interval counter for tree ");
- print_generic_expr (dump_file, hist->hvalue.tree.stmt,
+ print_generic_expr (dump_file, hist->hvalue.stmt,
TDF_SLIM);
fprintf (dump_file, ", range %d -- %d.\n",
hist->hdata.intvl.int_start,
if (dump_file)
{
fprintf (dump_file, "Pow2 counter for tree ");
- print_generic_expr (dump_file, hist->hvalue.tree.stmt, TDF_SLIM);
+ print_generic_expr (dump_file, hist->hvalue.stmt, TDF_SLIM);
fprintf (dump_file, ".\n");
}
hist->n_counters = 2;
if (dump_file)
{
fprintf (dump_file, "Single value counter for tree ");
- print_generic_expr (dump_file, hist->hvalue.tree.stmt, TDF_SLIM);
+ print_generic_expr (dump_file, hist->hvalue.stmt, TDF_SLIM);
fprintf (dump_file, ".\n");
}
hist->n_counters = 3;
if (dump_file)
{
fprintf (dump_file, "Constant delta counter for tree ");
- print_generic_expr (dump_file, hist->hvalue.tree.stmt, TDF_SLIM);
+ print_generic_expr (dump_file, hist->hvalue.stmt, TDF_SLIM);
fprintf (dump_file, ".\n");
}
hist->n_counters = 4;
return retval;
}
\f
-static bool
-gate_handle_value_profile_transformations (void)
-{
- return flag_branch_probabilities
- && flag_profile_values
- && !flag_tree_based_profiling
- && (flag_value_profile_transformations
- || flag_speculative_prefetching);
-}
-
-
-/* Do optimizations based on expression value profiles. */
-static void
-rest_of_handle_value_profile_transformations (void)
-{
- if (value_profile_transformations ())
- cleanup_cfg (CLEANUP_EXPENSIVE);
-}
-
-struct tree_opt_pass pass_value_profile_transformations =
-{
- "vpt", /* name */
- gate_handle_value_profile_transformations, /* gate */
- rest_of_handle_value_profile_transformations, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_VPT, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func, /* todo_flags_finish */
- 'V' /* letter */
-};
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