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re PR rtl-optimization/68212 (Loop unroller breaks basic block frequencies)

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PR rtl-optimization/68212
	* cfgloopmanip.c (duplicate_loop_to_header_edge): Use preheader edge
	frequency when computing scale factor for peeled copies.
	* loop-unroll.c (unroll_loop_runtime_iterations): Fix freq/count
	values for switch/peel blocks/edges.

From-SVN: r241170
This commit is contained in:
Pat Haugen 2016-10-14 17:10:18 +00:00 committed by Pat Haugen
parent a4744f620f
commit d4919e65ca
3 changed files with 43 additions and 4 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2016-10-14 Pat Haugen <pthaugen@us.ibm.com>
PR rtl-optimization/68212
* cfgloopmanip.c (duplicate_loop_to_header_edge): Use preheader edge
frequency when computing scale factor for peeled copies.
* loop-unroll.c (unroll_loop_runtime_iterations): Fix freq/count
values for switch/peel blocks/edges.
2016-10-14 Pedro Alves <palves@redhat.com>
* coretypes.h (OVERRIDE, FINAL): Delete, moved to

5
gcc/cfgloopmanip.c
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@ -1276,10 +1276,13 @@ duplicate_loop_to_header_edge (struct loop *loop, edge e,
}
else
{
int preheader_freq = EDGE_FREQUENCY (e);
scale_main = REG_BR_PROB_BASE;
for (i = 0; i < ndupl; i++)
scale_main = combine_probabilities (scale_main, scale_step[i]);
scale_act = REG_BR_PROB_BASE - prob_pass_thru;
if (preheader_freq > freq_in)
preheader_freq = freq_in;
scale_act = GCOV_COMPUTE_SCALE (preheader_freq, freq_in);
}
for (i = 0; i < ndupl; i++)
gcc_assert (scale_step[i] >= 0 && scale_step[i] <= REG_BR_PROB_BASE);

34
gcc/loop-unroll.c
View File

@ -859,7 +859,8 @@ unroll_loop_runtime_iterations (struct loop *loop)
rtx_insn *init_code, *branch_code;
unsigned i, j, p;
basic_block preheader, *body, swtch, ezc_swtch;
int may_exit_copy;
int may_exit_copy, iter_freq, new_freq;
gcov_type iter_count, new_count;
unsigned n_peel;
edge e;
bool extra_zero_check, last_may_exit;
@ -953,6 +954,15 @@ unroll_loop_runtime_iterations (struct loop *loop)
/* Record the place where switch will be built for preconditioning. */
swtch = split_edge (loop_preheader_edge (loop));
/* Compute frequency/count increments for each switch block and initialize
innermost switch block. Switch blocks and peeled loop copies are built
from innermost outward. */
iter_freq = new_freq = swtch->frequency / (max_unroll + 1);
iter_count = new_count = swtch->count / (max_unroll + 1);
swtch->frequency = new_freq;
swtch->count = new_count;
single_succ_edge (swtch)->count = new_count;
for (i = 0; i < n_peel; i++)
{
/* Peel the copy. */
@ -970,6 +980,10 @@ unroll_loop_runtime_iterations (struct loop *loop)
p = REG_BR_PROB_BASE / (i + 2);
preheader = split_edge (loop_preheader_edge (loop));
/* Add in frequency/count of edge from switch block. */
preheader->frequency += iter_freq;
preheader->count += iter_count;
single_succ_edge (preheader)->count = preheader->count;
branch_code = compare_and_jump_seq (copy_rtx (niter), GEN_INT (j), EQ,
block_label (preheader), p,
NULL);
@ -981,9 +995,14 @@ unroll_loop_runtime_iterations (struct loop *loop)
swtch = split_edge_and_insert (single_pred_edge (swtch), branch_code);
set_immediate_dominator (CDI_DOMINATORS, preheader, swtch);
single_succ_edge (swtch)->probability = REG_BR_PROB_BASE - p;
single_succ_edge (swtch)->count = new_count;
new_freq += iter_freq;
new_count += iter_count;
swtch->frequency = new_freq;
swtch->count = new_count;
e = make_edge (swtch, preheader,
single_succ_edge (swtch)->flags & EDGE_IRREDUCIBLE_LOOP);
e->count = RDIV (preheader->count * REG_BR_PROB_BASE, p);
e->count = iter_count;
e->probability = p;
}
@ -993,6 +1012,14 @@ unroll_loop_runtime_iterations (struct loop *loop)
p = REG_BR_PROB_BASE / (max_unroll + 1);
swtch = ezc_swtch;
preheader = split_edge (loop_preheader_edge (loop));
/* Recompute frequency/count adjustments since initial peel copy may
have exited and reduced those values that were computed above. */
iter_freq = swtch->frequency / (max_unroll + 1);
iter_count = swtch->count / (max_unroll + 1);
/* Add in frequency/count of edge from switch block. */
preheader->frequency += iter_freq;
preheader->count += iter_count;
single_succ_edge (preheader)->count = preheader->count;
branch_code = compare_and_jump_seq (copy_rtx (niter), const0_rtx, EQ,
block_label (preheader), p,
NULL);
@ -1001,9 +1028,10 @@ unroll_loop_runtime_iterations (struct loop *loop)
swtch = split_edge_and_insert (single_succ_edge (swtch), branch_code);
set_immediate_dominator (CDI_DOMINATORS, preheader, swtch);
single_succ_edge (swtch)->probability = REG_BR_PROB_BASE - p;
single_succ_edge (swtch)->count -= iter_count;
e = make_edge (swtch, preheader,
single_succ_edge (swtch)->flags & EDGE_IRREDUCIBLE_LOOP);
e->count = RDIV (preheader->count * REG_BR_PROB_BASE, p);
e->count = iter_count;
e->probability = p;
}