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ipa-inline-analysis.c (find_foldable_builtin_expect): Find the candidate of builtin_expect such that we should fix the size/time...

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* ipa-inline-analysis.c (find_foldable_builtin_expect): Find
        the candidate of builtin_expect such that we should fix the 
        size/time estimation.
        (estimate_function_body_sizes): Do the acutally size/time fix-up
        for builtin_expect.

From-SVN: r203168
This commit is contained in:
Rong Xu 2013-10-03 17:15:56 +00:00 committed by Rong Xu
parent 942df7390f
commit 111c3f39f5
2 changed files with 90 additions and 0 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2013-10-03 Rong Xu <xur@google.com>
* ipa-inline-analysis.c (find_foldable_builtin_expect): Find
the candidate of builtin_expect such that we should fix the
size/time estimation.
(estimate_function_body_sizes): Do the acutally size/time fix-up
for builtin_expect.
2013-10-03 Rong Xu <xur@google.com>
* predict.c (tree_predict_by_opcode): Get the probability

82
gcc/ipa-inline-analysis.c
View File

@ -2257,6 +2257,77 @@ array_index_predicate (struct inline_summary *info,
return p;
}
/* For a typical usage of __builtin_expect (a<b, 1), we
may introduce an extra relation stmt:
With the builtin, we have
t1 = a <= b;
t2 = (long int) t1;
t3 = __builtin_expect (t2, 1);
if (t3 != 0)
goto ...
Without the builtin, we have
if (a<=b)
goto...
This affects the size/time estimation and may have
an impact on the earlier inlining.
Here find this pattern and fix it up later. */
static gimple
find_foldable_builtin_expect (basic_block bb)
{
gimple_stmt_iterator bsi;
for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
{
gimple stmt = gsi_stmt (bsi);
if (gimple_call_builtin_p (stmt, BUILT_IN_EXPECT))
{
tree var = gimple_call_lhs (stmt);
tree arg = gimple_call_arg (stmt, 0);
use_operand_p use_p;
gimple use_stmt;
bool match = false;
bool done = false;
if (!var || !arg)
continue;
gcc_assert (TREE_CODE (var) == SSA_NAME);
while (TREE_CODE (arg) == SSA_NAME)
{
gimple stmt_tmp = SSA_NAME_DEF_STMT (arg);
if (!is_gimple_assign (stmt_tmp))
break;
switch (gimple_assign_rhs_code (stmt_tmp))
{
case LT_EXPR:
case LE_EXPR:
case GT_EXPR:
case GE_EXPR:
case EQ_EXPR:
case NE_EXPR:
match = true;
done = true;
break;
case NOP_EXPR:
break;
default:
done = true;
break;
}
if (done)
break;
arg = gimple_assign_rhs1 (stmt_tmp);
}
if (match && single_imm_use (var, &use_p, &use_stmt)
&& gimple_code (use_stmt) == GIMPLE_COND)
return use_stmt;
}
}
return NULL;
}
/* Compute function body size parameters for NODE.
When EARLY is true, we compute only simple summaries without
non-trivial predicates to drive the early inliner. */
@ -2280,6 +2351,7 @@ estimate_function_body_sizes (struct cgraph_node *node, bool early)
int nblocks, n;
int *order;
predicate array_index = true_predicate ();
gimple fix_builtin_expect_stmt;
info->conds = NULL;
info->entry = NULL;
@ -2360,6 +2432,8 @@ estimate_function_body_sizes (struct cgraph_node *node, bool early)
}
}
fix_builtin_expect_stmt = find_foldable_builtin_expect (bb);
for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
{
gimple stmt = gsi_stmt (bsi);
@ -2368,6 +2442,14 @@ estimate_function_body_sizes (struct cgraph_node *node, bool early)
int prob;
struct predicate will_be_nonconstant;
/* This relation stmt should be folded after we remove
buildin_expect call. Adjust the cost here. */
if (stmt == fix_builtin_expect_stmt)
{
this_size--;
this_time--;
}
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, " ");