+2008-05-18 Xinliang David Li <davidxl@google.com>
+
+ * gcc/tree-ssa-dce.c: Coding style fix.
+ (check_pow): Documentation comment.
+ (check_log): Documenation comment. Coding style fix.
+ (is_unnecessary_except_errno_call): Ditto.
+ (gen_conditions_for_pow): Ditto.
+ (gen_conditions_for_log): Ditto.
+ (gen_shrink_wrap_conditions): Ditto.
+ (shrink_wrap_one_built_in_calls): Ditto.
+ * gcc/doc/invoke.texi: Better documentation string.
+ * ChangeLog: Fix wrong change log entries from
+ May 17 checkin on function call DCE.
+
2008-05-17 Kaz Kojima <kkojima@gcc.gnu.org>
* config/sh/sh.c (sh_output_mi_thunk): Update the use of
* fold-const.c (fold_unary) <CASE_CONVERT>: Fold the cast into
a BIT_AND_EXPR only for an INTEGER_TYPE.
+2008-05-17 Xinliang David Li <davidxl@google.com>
+
+ * gcc/tree-ssa-dce.c (cond_dead_built_in_calls): New static variable.
+ (check_pow, check_log, is_unnecessary_except_errno_call): New
+ functions to check for eliminating math functions that are pure
+ except for setting errno.
+ (gen_conditions_for_pow, gen_conditionas_for_log): New functions to
+ general condition expressions for shrink-wrapping pow/log calls.
+ (gen_shrink_wrap_conditions): Ditto.
+ (shrink_wrap_one_built_in_call): Ditto.
+ (shrink_wrap_conditional_dead_built_in_calls): Ditto.
+ (mark_operand_necessary): If debugging, output if OP is necessary.
+ (eliminate_unnecessary_stmts): Eliminate pow, log calls that are
+ unnecessary.
+ * gcc/opts.c (decode_options): set flag_tree_builtin_dce to 1 when
+ opt level >= 2.
+ * gcc/common.opt: New user flag -ftree-builtin-dce.
+ * gcc/doc/invoke.texi (-ftree-builtin-dce): New option.
+
2008-05-16 David S. Miller <davem@davemloft.net>
* config/sparc/linux.h (NO_PROFILE_COUNTERS): Undef before
if (error_cond(args))
built_in_call(args)
- ( An actual simple exampl is :
+ An actual simple exampl is :
log (x); // Mostly dead call
==>
if (x < 0)
in majority of the cases, log won't be called with x out of
range. The branch is totally predicatible, so the branch cost
is low. Such optimization improves the performance of
- an important application in a big search company by 20% )
+ an important application in a big search company.
Note that library functions are not supposed to clear errno to zero without
error.
inlining). */
+/* A helper method to help select calls to pow that are suitable for
+ conditional DCE transformation. Returns true if the pow call is
+ a candidate.*/
+
static bool
check_pow (tree pow_call)
{
return false;
}
+/* A helper function to help select candidate calls to log that are
+ suitable for conditional DCE. Returns true if the log call is a
+ candidate. */
+
static bool
check_log (tree log_call)
{
}
-/* A helper function to determine if a builtin function
- call is a candidate for conditional DCE. */
+/* A helper function to determine if a builtin function call is a
+ candidate for conditional DCE. Returns true if the builtin call
+ is a candidate. */
static bool
is_unnecessary_except_errno_call (tree call)
if (!flag_tree_builtin_dce)
return false;
- gcc_assert (call);
- gcc_assert (!DECL_P (call));
- gcc_assert (TREE_CODE (call) == CALL_EXPR);
+ gcc_assert (call && TREE_CODE (call) == CALL_EXPR);
fn = get_callee_fndecl (call);
if (!fn || !DECL_BUILT_IN (fn))
fnc = DECL_FUNCTION_CODE (fn);
switch (fnc)
- {
- CASE_FLT_FN (BUILT_IN_POW):
- if (check_pow (call))
- is_unnecessary_except_errno = true;
- break;
+ {
+ CASE_FLT_FN (BUILT_IN_POW):
+ if (check_pow (call))
+ is_unnecessary_except_errno = true;
+ break;
- CASE_FLT_FN (BUILT_IN_LOG):
- if (check_log (call))
- is_unnecessary_except_errno = true;
- break;
- default :
- is_unnecessary_except_errno = false;
- break;
+ CASE_FLT_FN (BUILT_IN_LOG):
+ if (check_log (call))
+ is_unnecessary_except_errno = true;
+ break;
+ default :
+ is_unnecessary_except_errno = false;
+ break;
}
- if (!is_unnecessary_except_errno)
- return false;
-
return is_unnecessary_except_errno;
}
}
}
-/* Method to generate conditional statements for guarding condionally
- dead calls to pow. One or more statements can be generated for
- each logical condition. Statement groups of different conditions
- are separated by a NULL tree. */
+/* Method to generate conditional statements for guarding condionally
+ dead calls to pow. One or more statements can be generated for
+ each logical condition. Statement groups of different conditions
+ are separated by a NULL tree and they are stored in the VEC
+ conds. The number of logical conditions are stored in *nconds. */
static void
gen_conditions_for_pow (tree pow_call, enum built_in_function fnc,
VEC (tree, heap)* conds, unsigned * nconds)
VEC_safe_push (tree, heap, conds, stmt3);
(*nconds)++;
- /* now a seperator*/
+ /* Now a seperator*/
VEC_safe_push (tree, heap, conds, NULL);
temp1 = create_tmp_var (int_typ, "DCE_COND1");
gcc_unreachable ();
}
-/* The method to generate error condition guard code for log(x)
- calls. */
+/* The method to generate error condition guard code for log(x)
+ calls. */
static void
gen_conditions_for_log (tree call, enum built_in_function fnc,
VEC (tree, heap)* conds, unsigned * nconds)
enum built_in_function fnc;
gcc_assert (nconds && conds);
gcc_assert (VEC_length(tree, conds) == 0);
- gcc_assert (TREE_CODE (bi_call) == GIMPLE_MODIFY_STMT ||
- TREE_CODE (bi_call) == CALL_EXPR);
+ gcc_assert (TREE_CODE (bi_call) == GIMPLE_MODIFY_STMT
+ || TREE_CODE (bi_call) == CALL_EXPR);
call = bi_call;
if (TREE_CODE (call) == GIMPLE_MODIFY_STMT)
*nconds = 0;
switch (fnc)
- {
- /*CASE_FLT_FN(BUILT_IN_POW)*/
+ {
case BUILT_IN_POW:
gen_conditions_for_pow (call, fnc, conds, nconds);
- break;
- /*CASE_FLT_FN(BUILT_IN_LOG):*/
+ break;
case BUILT_IN_LOG:
case BUILT_IN_LOGF:
case BUILT_IN_LOGL:
gen_conditions_for_log (call, fnc, conds, nconds);
- break;
+ break;
default :
- gcc_assert (0);
+ gcc_unreachable();
break;
}
}
+/* Propability of the branch (to the call) is taken. */
#define ERR_PROB 0.01
/* The method to shrink wrap a partially dead builtin call
{
tree c = VEC_index (tree, conds, ci);
gcc_assert ( c || ci != 0 );
- if (!c) break;
+ if (!c)
+ break;
bsi_insert_before (&bi_call_bsi, c, BSI_SAME_STMT);
cond_expr = c;
}
ci ++;
gcc_assert (cond_expr && TREE_CODE (cond_expr) == COND_EXPR);
- /* now the label*/
+ /* Now the label*/
bi_call_label_decl = create_artificial_label ();
bi_call_label = build1 (LABEL_EXPR, void_type_node, bi_call_label_decl);
bsi_insert_before (&bi_call_bsi, bi_call_label, BSI_SAME_STMT);
join_tgt_in_edge_fall_thru->probability =
REG_BR_PROB_BASE - bi_call_in_edge0->probability;
- /* code generation for the rest of the conditions */
+ /* Code generation for the rest of the conditions */
guard_bb = guard_bb0;
for (; nconds > 0; )
{
bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_TRUE_VALUE);
- bi_call_in_edge->probability = REG_BR_PROB_BASE*ERR_PROB;
+ bi_call_in_edge->probability = REG_BR_PROB_BASE * ERR_PROB;
guard_bb_in_edge->probability =
REG_BR_PROB_BASE - bi_call_in_edge->probability;
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