+2015-11-17 Richard Sandiford <richard.sandiford@arm.com>
+
+ * builtins.c (expand_errno_check, expand_builtin_mathfn)
+ (expand_builtin_mathfn_2): Delete.
+ (expand_builtin): Remove handling of functions with
+ internal function equivalents.
+ * internal-fn.def (SET_EDOM): New internal function.
+ * internal-fn.h (set_edom_supported_p): Declare.
+ * internal-fn.c (expand_SET_EDOM): New function.
+ (set_edom_supported_p): Likewise.
+ * tree-call-cdce.c: Include builtins.h and internal-fn.h.
+ Rewrite comment at head of file.
+ (is_call_dce_candidate): Rename to...
+ (can_test_argument_range): ...this. Don't check gimple_call_lhs
+ or gimple_call_builtin_p here.
+ (edom_only_function): New function.
+ (shrink_wrap_one_built_in_call_with_conds): New function, split out
+ from...
+ (shrink_wrap_one_built_in_call): ...here.
+ (can_use_internal_fn, use_internal_fn): New functions.
+ (shrink_wrap_conditional_dead_built_in_calls): Call use_internal_fn
+ for calls that have an lhs.
+ (pass_call_cdce::gate): Remove optimize_function_for_speed_p check.
+ (pass_call_cdce::execute): Skip blocks that are optimized for size.
+ Check gimple_call_builtin_p here. Use can_use_internal_fn for
+ calls with an lhs.
+ * opts.c (default_options_table): Enable -ftree-builtin-call-cdce
+ at -O and above.
+
2015-11-17 Richard Sandiford <richard.sandiford@arm.com>
* builtins.h (called_as_built_in): Declare.
static void expand_builtin_return (rtx);
static enum type_class type_to_class (tree);
static rtx expand_builtin_classify_type (tree);
-static void expand_errno_check (tree, rtx);
-static rtx expand_builtin_mathfn (tree, rtx, rtx);
-static rtx expand_builtin_mathfn_2 (tree, rtx, rtx);
static rtx expand_builtin_mathfn_3 (tree, rtx, rtx);
static rtx expand_builtin_mathfn_ternary (tree, rtx, rtx);
static rtx expand_builtin_interclass_mathfn (tree, rtx);
return IFN_LAST;
}
-/* If errno must be maintained, expand the RTL to check if the result,
- TARGET, of a built-in function call, EXP, is NaN, and if so set
- errno to EDOM. */
-
-static void
-expand_errno_check (tree exp, rtx target)
-{
- rtx_code_label *lab = gen_label_rtx ();
-
- /* Test the result; if it is NaN, set errno=EDOM because
- the argument was not in the domain. */
- do_compare_rtx_and_jump (target, target, EQ, 0, GET_MODE (target),
- NULL_RTX, NULL, lab,
- /* The jump is very likely. */
- REG_BR_PROB_BASE - (REG_BR_PROB_BASE / 2000 - 1));
-
-#ifdef TARGET_EDOM
- /* If this built-in doesn't throw an exception, set errno directly. */
- if (TREE_NOTHROW (TREE_OPERAND (CALL_EXPR_FN (exp), 0)))
- {
-#ifdef GEN_ERRNO_RTX
- rtx errno_rtx = GEN_ERRNO_RTX;
-#else
- rtx errno_rtx
- = gen_rtx_MEM (word_mode, gen_rtx_SYMBOL_REF (Pmode, "errno"));
-#endif
- emit_move_insn (errno_rtx,
- gen_int_mode (TARGET_EDOM, GET_MODE (errno_rtx)));
- emit_label (lab);
- return;
- }
-#endif
-
- /* Make sure the library call isn't expanded as a tail call. */
- CALL_EXPR_TAILCALL (exp) = 0;
-
- /* We can't set errno=EDOM directly; let the library call do it.
- Pop the arguments right away in case the call gets deleted. */
- NO_DEFER_POP;
- expand_call (exp, target, 0);
- OK_DEFER_POP;
- emit_label (lab);
-}
-
-/* Expand a call to one of the builtin math functions (sqrt, exp, or log).
- Return NULL_RTX if a normal call should be emitted rather than expanding
- the function in-line. EXP is the expression that is a call to the builtin
- function; if convenient, the result should be placed in TARGET.
- SUBTARGET may be used as the target for computing one of EXP's operands. */
-
-static rtx
-expand_builtin_mathfn (tree exp, rtx target, rtx subtarget)
-{
- optab builtin_optab;
- rtx op0;
- rtx_insn *insns;
- tree fndecl = get_callee_fndecl (exp);
- machine_mode mode;
- bool errno_set = false;
- bool try_widening = false;
- tree arg;
-
- if (!validate_arglist (exp, REAL_TYPE, VOID_TYPE))
- return NULL_RTX;
-
- arg = CALL_EXPR_ARG (exp, 0);
-
- switch (DECL_FUNCTION_CODE (fndecl))
- {
- CASE_FLT_FN (BUILT_IN_SQRT):
- errno_set = ! tree_expr_nonnegative_p (arg);
- try_widening = true;
- builtin_optab = sqrt_optab;
- break;
- CASE_FLT_FN (BUILT_IN_EXP):
- errno_set = true; builtin_optab = exp_optab; break;
- CASE_FLT_FN (BUILT_IN_EXP10):
- CASE_FLT_FN (BUILT_IN_POW10):
- errno_set = true; builtin_optab = exp10_optab; break;
- CASE_FLT_FN (BUILT_IN_EXP2):
- errno_set = true; builtin_optab = exp2_optab; break;
- CASE_FLT_FN (BUILT_IN_EXPM1):
- errno_set = true; builtin_optab = expm1_optab; break;
- CASE_FLT_FN (BUILT_IN_LOGB):
- errno_set = true; builtin_optab = logb_optab; break;
- CASE_FLT_FN (BUILT_IN_LOG):
- errno_set = true; builtin_optab = log_optab; break;
- CASE_FLT_FN (BUILT_IN_LOG10):
- errno_set = true; builtin_optab = log10_optab; break;
- CASE_FLT_FN (BUILT_IN_LOG2):
- errno_set = true; builtin_optab = log2_optab; break;
- CASE_FLT_FN (BUILT_IN_LOG1P):
- errno_set = true; builtin_optab = log1p_optab; break;
- CASE_FLT_FN (BUILT_IN_ASIN):
- builtin_optab = asin_optab; break;
- CASE_FLT_FN (BUILT_IN_ACOS):
- builtin_optab = acos_optab; break;
- CASE_FLT_FN (BUILT_IN_TAN):
- builtin_optab = tan_optab; break;
- CASE_FLT_FN (BUILT_IN_ATAN):
- builtin_optab = atan_optab; break;
- CASE_FLT_FN (BUILT_IN_FLOOR):
- builtin_optab = floor_optab; break;
- CASE_FLT_FN (BUILT_IN_CEIL):
- builtin_optab = ceil_optab; break;
- CASE_FLT_FN (BUILT_IN_TRUNC):
- builtin_optab = btrunc_optab; break;
- CASE_FLT_FN (BUILT_IN_ROUND):
- builtin_optab = round_optab; break;
- CASE_FLT_FN (BUILT_IN_NEARBYINT):
- builtin_optab = nearbyint_optab;
- if (flag_trapping_math)
- break;
- /* Else fallthrough and expand as rint. */
- CASE_FLT_FN (BUILT_IN_RINT):
- builtin_optab = rint_optab; break;
- CASE_FLT_FN (BUILT_IN_SIGNIFICAND):
- builtin_optab = significand_optab; break;
- default:
- gcc_unreachable ();
- }
-
- /* Make a suitable register to place result in. */
- mode = TYPE_MODE (TREE_TYPE (exp));
-
- if (! flag_errno_math || ! HONOR_NANS (mode))
- errno_set = false;
-
- /* Before working hard, check whether the instruction is available, but try
- to widen the mode for specific operations. */
- if ((optab_handler (builtin_optab, mode) != CODE_FOR_nothing
- || (try_widening && !excess_precision_type (TREE_TYPE (exp))))
- && (!errno_set || !optimize_insn_for_size_p ()))
- {
- rtx result = gen_reg_rtx (mode);
-
- /* Wrap the computation of the argument in a SAVE_EXPR, as we may
- need to expand the argument again. This way, we will not perform
- side-effects more the once. */
- CALL_EXPR_ARG (exp, 0) = arg = builtin_save_expr (arg);
-
- op0 = expand_expr (arg, subtarget, VOIDmode, EXPAND_NORMAL);
-
- start_sequence ();
-
- /* Compute into RESULT.
- Set RESULT to wherever the result comes back. */
- result = expand_unop (mode, builtin_optab, op0, result, 0);
-
- if (result != 0)
- {
- if (errno_set)
- expand_errno_check (exp, result);
-
- /* Output the entire sequence. */
- insns = get_insns ();
- end_sequence ();
- emit_insn (insns);
- return result;
- }
-
- /* If we were unable to expand via the builtin, stop the sequence
- (without outputting the insns) and call to the library function
- with the stabilized argument list. */
- end_sequence ();
- }
-
- return expand_call (exp, target, target == const0_rtx);
-}
-
-/* Expand a call to the builtin binary math functions (pow and atan2).
- Return NULL_RTX if a normal call should be emitted rather than expanding the
- function in-line. EXP is the expression that is a call to the builtin
- function; if convenient, the result should be placed in TARGET.
- SUBTARGET may be used as the target for computing one of EXP's
- operands. */
-
-static rtx
-expand_builtin_mathfn_2 (tree exp, rtx target, rtx subtarget)
-{
- optab builtin_optab;
- rtx op0, op1, result;
- rtx_insn *insns;
- int op1_type = REAL_TYPE;
- tree fndecl = get_callee_fndecl (exp);
- tree arg0, arg1;
- machine_mode mode;
- bool errno_set = true;
-
- switch (DECL_FUNCTION_CODE (fndecl))
- {
- CASE_FLT_FN (BUILT_IN_SCALBN):
- CASE_FLT_FN (BUILT_IN_SCALBLN):
- CASE_FLT_FN (BUILT_IN_LDEXP):
- op1_type = INTEGER_TYPE;
- default:
- break;
- }
-
- if (!validate_arglist (exp, REAL_TYPE, op1_type, VOID_TYPE))
- return NULL_RTX;
-
- arg0 = CALL_EXPR_ARG (exp, 0);
- arg1 = CALL_EXPR_ARG (exp, 1);
-
- switch (DECL_FUNCTION_CODE (fndecl))
- {
- CASE_FLT_FN (BUILT_IN_POW):
- builtin_optab = pow_optab; break;
- CASE_FLT_FN (BUILT_IN_ATAN2):
- builtin_optab = atan2_optab; break;
- CASE_FLT_FN (BUILT_IN_SCALB):
- if (REAL_MODE_FORMAT (TYPE_MODE (TREE_TYPE (exp)))->b != 2)
- return 0;
- builtin_optab = scalb_optab; break;
- CASE_FLT_FN (BUILT_IN_SCALBN):
- CASE_FLT_FN (BUILT_IN_SCALBLN):
- if (REAL_MODE_FORMAT (TYPE_MODE (TREE_TYPE (exp)))->b != 2)
- return 0;
- /* Fall through... */
- CASE_FLT_FN (BUILT_IN_LDEXP):
- builtin_optab = ldexp_optab; break;
- CASE_FLT_FN (BUILT_IN_FMOD):
- builtin_optab = fmod_optab; break;
- CASE_FLT_FN (BUILT_IN_REMAINDER):
- CASE_FLT_FN (BUILT_IN_DREM):
- builtin_optab = remainder_optab; break;
- default:
- gcc_unreachable ();
- }
-
- /* Make a suitable register to place result in. */
- mode = TYPE_MODE (TREE_TYPE (exp));
-
- /* Before working hard, check whether the instruction is available. */
- if (optab_handler (builtin_optab, mode) == CODE_FOR_nothing)
- return NULL_RTX;
-
- result = gen_reg_rtx (mode);
-
- if (! flag_errno_math || ! HONOR_NANS (mode))
- errno_set = false;
-
- if (errno_set && optimize_insn_for_size_p ())
- return 0;
-
- /* Always stabilize the argument list. */
- CALL_EXPR_ARG (exp, 0) = arg0 = builtin_save_expr (arg0);
- CALL_EXPR_ARG (exp, 1) = arg1 = builtin_save_expr (arg1);
-
- op0 = expand_expr (arg0, subtarget, VOIDmode, EXPAND_NORMAL);
- op1 = expand_normal (arg1);
-
- start_sequence ();
-
- /* Compute into RESULT.
- Set RESULT to wherever the result comes back. */
- result = expand_binop (mode, builtin_optab, op0, op1,
- result, 0, OPTAB_DIRECT);
-
- /* If we were unable to expand via the builtin, stop the sequence
- (without outputting the insns) and call to the library function
- with the stabilized argument list. */
- if (result == 0)
- {
- end_sequence ();
- return expand_call (exp, target, target == const0_rtx);
- }
-
- if (errno_set)
- expand_errno_check (exp, result);
-
- /* Output the entire sequence. */
- insns = get_insns ();
- end_sequence ();
- emit_insn (insns);
-
- return result;
-}
-
/* Expand a call to the builtin trinary math functions (fma).
Return NULL_RTX if a normal call should be emitted rather than expanding the
function in-line. EXP is the expression that is a call to the builtin
CASE_FLT_FN (BUILT_IN_CABS):
break;
- CASE_FLT_FN (BUILT_IN_EXP):
- CASE_FLT_FN (BUILT_IN_EXP10):
- CASE_FLT_FN (BUILT_IN_POW10):
- CASE_FLT_FN (BUILT_IN_EXP2):
- CASE_FLT_FN (BUILT_IN_EXPM1):
- CASE_FLT_FN (BUILT_IN_LOGB):
- CASE_FLT_FN (BUILT_IN_LOG):
- CASE_FLT_FN (BUILT_IN_LOG10):
- CASE_FLT_FN (BUILT_IN_LOG2):
- CASE_FLT_FN (BUILT_IN_LOG1P):
- CASE_FLT_FN (BUILT_IN_TAN):
- CASE_FLT_FN (BUILT_IN_ASIN):
- CASE_FLT_FN (BUILT_IN_ACOS):
- CASE_FLT_FN (BUILT_IN_ATAN):
- CASE_FLT_FN (BUILT_IN_SIGNIFICAND):
- /* Treat these like sqrt only if unsafe math optimizations are allowed,
- because of possible accuracy problems. */
- if (! flag_unsafe_math_optimizations)
- break;
- CASE_FLT_FN (BUILT_IN_SQRT):
- CASE_FLT_FN (BUILT_IN_FLOOR):
- CASE_FLT_FN (BUILT_IN_CEIL):
- CASE_FLT_FN (BUILT_IN_TRUNC):
- CASE_FLT_FN (BUILT_IN_ROUND):
- CASE_FLT_FN (BUILT_IN_NEARBYINT):
- CASE_FLT_FN (BUILT_IN_RINT):
- target = expand_builtin_mathfn (exp, target, subtarget);
- if (target)
- return target;
- break;
-
CASE_FLT_FN (BUILT_IN_FMA):
target = expand_builtin_mathfn_ternary (exp, target, subtarget);
if (target)
return target;
break;
- CASE_FLT_FN (BUILT_IN_ATAN2):
- CASE_FLT_FN (BUILT_IN_LDEXP):
- CASE_FLT_FN (BUILT_IN_SCALB):
- CASE_FLT_FN (BUILT_IN_SCALBN):
- CASE_FLT_FN (BUILT_IN_SCALBLN):
- if (! flag_unsafe_math_optimizations)
- break;
-
- CASE_FLT_FN (BUILT_IN_FMOD):
- CASE_FLT_FN (BUILT_IN_REMAINDER):
- CASE_FLT_FN (BUILT_IN_DREM):
- CASE_FLT_FN (BUILT_IN_POW):
- target = expand_builtin_mathfn_2 (exp, target, subtarget);
- if (target)
- return target;
- break;
-
CASE_FLT_FN (BUILT_IN_CEXPI):
target = expand_builtin_cexpi (exp, target);
gcc_assert (target);
gcc_unreachable ();
}
+/* Set errno to EDOM. */
+
+static void
+expand_SET_EDOM (internal_fn, gcall *)
+{
+#ifdef TARGET_EDOM
+#ifdef GEN_ERRNO_RTX
+ rtx errno_rtx = GEN_ERRNO_RTX;
+#else
+ rtx errno_rtx = gen_rtx_MEM (word_mode, gen_rtx_SYMBOL_REF (Pmode, "errno"));
+#endif
+ emit_move_insn (errno_rtx,
+ gen_int_mode (TARGET_EDOM, GET_MODE (errno_rtx)));
+#else
+ gcc_unreachable ();
+#endif
+}
+
/* Expand a call to FN using the operands in STMT. FN has a single
output operand and NARGS input operands. */
return direct_internal_fn_supported_p (fn, tree_pair (type, type));
}
+/* Return true if IFN_SET_EDOM is supported. */
+
+bool
+set_edom_supported_p (void)
+{
+#ifdef TARGET_EDOM
+ return true;
+#else
+ return false;
+#endif
+}
+
#define DEF_INTERNAL_OPTAB_FN(CODE, FLAGS, OPTAB, TYPE) \
static void \
expand_##CODE (internal_fn fn, gcall *stmt) \
/* OpenACC reduction abstraction. See internal-fn.h for usage. */
DEF_INTERNAL_FN (GOACC_REDUCTION, ECF_NOTHROW | ECF_LEAF, NULL)
+/* Set errno to EDOM, if GCC knows how to do that directly for the
+ current target. */
+DEF_INTERNAL_FN (SET_EDOM, ECF_LEAF | ECF_NOTHROW, NULL)
+
#undef DEF_INTERNAL_INT_FN
#undef DEF_INTERNAL_FLT_FN
#undef DEF_INTERNAL_OPTAB_FN
extern tree_pair direct_internal_fn_types (internal_fn, gcall *);
extern bool direct_internal_fn_supported_p (internal_fn, tree_pair);
extern bool direct_internal_fn_supported_p (internal_fn, tree);
+extern bool set_edom_supported_p (void);
extern void expand_internal_call (gcall *);
extern void expand_internal_call (internal_fn, gcall *);
{ OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fmove_loop_invariants, NULL, 1 },
{ OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_ftree_pta, NULL, 1 },
{ OPT_LEVELS_1_PLUS_NOT_DEBUG, OPT_fssa_phiopt, NULL, 1 },
+ { OPT_LEVELS_1_PLUS, OPT_ftree_builtin_call_dce, NULL, 1 },
/* -O2 optimizations. */
{ OPT_LEVELS_2_PLUS, OPT_finline_small_functions, NULL, 1 },
REORDER_BLOCKS_ALGORITHM_STC },
{ OPT_LEVELS_2_PLUS, OPT_freorder_functions, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_ftree_vrp, NULL, 1 },
- { OPT_LEVELS_2_PLUS, OPT_ftree_builtin_call_dce, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_ftree_pre, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_ftree_switch_conversion, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_fipa_cp, NULL, 1 },
#include "gimple-iterator.h"
#include "tree-cfg.h"
#include "tree-into-ssa.h"
+#include "builtins.h"
+#include "internal-fn.h"
\f
-/* Conditional dead call elimination
+/* This pass serves two closely-related purposes:
- Some builtin functions can set errno on error conditions, but they
- are otherwise pure. If the result of a call to such a function is
- not used, the compiler can still not eliminate the call without
- powerful interprocedural analysis to prove that the errno is not
- checked. However, if the conditions under which the error occurs
- are known, the compiler can conditionally dead code eliminate the
- calls by shrink-wrapping the semi-dead calls into the error condition:
+ 1. It conditionally executes calls that set errno if (a) the result of
+ the call is unused and (b) a simple range check on the arguments can
+ detect most cases where errno does not need to be set.
- built_in_call (args)
- ==>
- if (error_cond (args))
- built_in_call (args)
+ This is the "conditional dead-code elimination" that gave the pass
+ its original name, since the call is dead for most argument values.
+ The calls for which it helps are usually part of the C++ abstraction
+ penalty exposed after inlining.
+
+ 2. It looks for calls to built-in functions that set errno and whose
+ result is used. It checks whether there is an associated internal
+ function that doesn't set errno and whether the target supports
+ that internal function. If so, the pass uses the internal function
+ to compute the result of the built-in function but still arranges
+ for errno to be set when necessary. There are two ways of setting
+ errno:
+
+ a. by protecting the original call with the same argument checks as (1)
+
+ b. by protecting the original call with a check that the result
+ of the internal function is not equal to itself (i.e. is NaN).
+
+ (b) requires that NaNs are the only erroneous results. It is not
+ appropriate for functions like log, which returns ERANGE for zero
+ arguments. (b) is also likely to perform worse than (a) because it
+ requires the result to be calculated first. The pass therefore uses
+ (a) when it can and uses (b) as a fallback.
+
+ For (b) the pass can replace the original call with a call to
+ IFN_SET_EDOM, if the target supports direct assignments to errno.
+
+ In both cases, arguments that require errno to be set should occur
+ rarely in practice. Checks of the errno result should also be rare,
+ but the compiler would need powerful interprocedural analysis to
+ prove that errno is not checked. It's much easier to add argument
+ checks or result checks instead.
+
+ An example of (1) is:
- An actual simple example is :
log (x); // Mostly dead call
==>
if (__builtin_islessequal (x, 0))
log (x);
With this change, call to log (x) is effectively eliminated, as
- in majority of the cases, log won't be called with x out of
+ in the majority of the cases, log won't be called with x out of
range. The branch is totally predictable, so the branch cost
is low.
+ An example of (2) is:
+
+ y = sqrt (x);
+ ==>
+ y = IFN_SQRT (x);
+ if (__builtin_isless (x, 0))
+ sqrt (x);
+
+ In the vast majority of cases we should then never need to call sqrt.
+
Note that library functions are not supposed to clear errno to zero without
error. See IEEE Std 1003.1, section 2.3 Error Numbers, and section 7.5:3 of
ISO/IEC 9899 (C99).
The condition wrapping the builtin call is conservatively set to avoid too
- aggressive (wrong) shrink wrapping. The optimization is called conditional
- dead call elimination because the call is eliminated under the condition
- that the input arguments would not lead to domain or range error (for
- instance when x <= 0 for a log (x) call), however the chances that the error
- condition is hit is very low (those builtin calls which are conditionally
- dead are usually part of the C++ abstraction penalty exposed after
- inlining). */
+ aggressive (wrong) shrink wrapping. */
/* A structure for representing input domain of
return check_target_format (arg);
}
-/* 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. */
+/* Return true if built-in function call CALL calls a math function
+ and if we know how to test the range of its arguments to detect _most_
+ situations in which errno is not set. The test must err on the side
+ of treating non-erroneous values as potentially erroneous. */
static bool
-is_call_dce_candidate (gcall *call)
+can_test_argument_range (gcall *call)
{
- tree fn;
- enum built_in_function fnc;
-
- /* Only potentially dead calls are considered. */
- if (gimple_call_lhs (call))
- return false;
-
- fn = gimple_call_fndecl (call);
- if (!fn
- || !DECL_BUILT_IN (fn)
- || (DECL_BUILT_IN_CLASS (fn) != BUILT_IN_NORMAL))
- return false;
-
- fnc = DECL_FUNCTION_CODE (fn);
- switch (fnc)
+ switch (DECL_FUNCTION_CODE (gimple_call_fndecl (call)))
{
/* Trig functions. */
CASE_FLT_FN (BUILT_IN_ACOS):
return false;
}
+/* Return true if CALL can produce a domain error (EDOM) but can never
+ produce a pole, range overflow or range underflow error (all ERANGE).
+ This means that we can tell whether a function would have set errno
+ by testing whether the result is a NaN. */
+
+static bool
+edom_only_function (gcall *call)
+{
+ switch (DECL_FUNCTION_CODE (gimple_call_fndecl (call)))
+ {
+ CASE_FLT_FN (BUILT_IN_ACOS):
+ CASE_FLT_FN (BUILT_IN_ASIN):
+ CASE_FLT_FN (BUILT_IN_ATAN):
+ CASE_FLT_FN (BUILT_IN_COS):
+ CASE_FLT_FN (BUILT_IN_SIGNIFICAND):
+ CASE_FLT_FN (BUILT_IN_SIN):
+ CASE_FLT_FN (BUILT_IN_SQRT):
+ CASE_FLT_FN (BUILT_IN_FMOD):
+ CASE_FLT_FN (BUILT_IN_REMAINDER):
+ return true;
+
+ default:
+ return false;
+ }
+}
\f
/* A helper function to generate gimple statements for one bound
comparison, so that the built-in function is called whenever
/* Probability of the branch (to the call) is taken. */
#define ERR_PROB 0.01
-/* The function to shrink wrap a partially dead builtin call
- whose return value is not used anywhere, but has to be kept
- live due to potential error condition. Returns true if the
- transformation actually happens. */
+/* Shrink-wrap BI_CALL so that it is only called when one of the NCONDS
+ conditions in CONDS is false.
+
+ Return true on success, in which case the cfg will have been updated. */
static bool
-shrink_wrap_one_built_in_call (gcall *bi_call)
+shrink_wrap_one_built_in_call_with_conds (gcall *bi_call, vec <gimple *> conds,
+ unsigned int nconds)
{
gimple_stmt_iterator bi_call_bsi;
basic_block bi_call_bb, join_tgt_bb, guard_bb;
edge join_tgt_in_edge_from_call, join_tgt_in_edge_fall_thru;
edge bi_call_in_edge0, guard_bb_in_edge;
- unsigned tn_cond_stmts, nconds;
+ unsigned tn_cond_stmts;
unsigned ci;
gimple *cond_expr = NULL;
gimple *cond_expr_start;
- auto_vec<gimple *, 12> conds;
- gen_shrink_wrap_conditions (bi_call, conds, &nconds);
-
- /* This can happen if the condition generator decides
- it is not beneficial to do the transformation. Just
- return false and do not do any transformation for
- the call. */
- if (nconds == 0)
- return false;
-
/* The cfg we want to create looks like this:
[guard n-1] <- guard_bb (old block)
return true;
}
+/* Shrink-wrap BI_CALL so that it is only called when it might set errno
+ (but is always called if it would set errno).
+
+ Return true on success, in which case the cfg will have been updated. */
+
+static bool
+shrink_wrap_one_built_in_call (gcall *bi_call)
+{
+ unsigned nconds = 0;
+ auto_vec<gimple *, 12> conds;
+ gen_shrink_wrap_conditions (bi_call, conds, &nconds);
+ /* This can happen if the condition generator decides
+ it is not beneficial to do the transformation. Just
+ return false and do not do any transformation for
+ the call. */
+ if (nconds == 0)
+ return false;
+ return shrink_wrap_one_built_in_call_with_conds (bi_call, conds, nconds);
+}
+
+/* Return true if built-in function call CALL could be implemented using
+ a combination of an internal function to compute the result and a
+ separate call to set errno. */
+
+static bool
+can_use_internal_fn (gcall *call)
+{
+ /* Only replace calls that set errno. */
+ if (!gimple_vdef (call))
+ return false;
+
+ /* Punt if we can't conditionalize the call. */
+ basic_block bb = gimple_bb (call);
+ if (stmt_ends_bb_p (call) && !find_fallthru_edge (bb->succs))
+ return false;
+
+ /* See whether there is an internal function for this built-in. */
+ if (replacement_internal_fn (call) == IFN_LAST)
+ return false;
+
+ /* See whether we can catch all cases where errno would be set,
+ while still avoiding the call in most cases. */
+ if (!can_test_argument_range (call)
+ && !edom_only_function (call))
+ return false;
+
+ return true;
+}
+
+/* Implement built-in function call CALL using an internal function.
+ Return true on success, in which case the cfg will have changed. */
+
+static bool
+use_internal_fn (gcall *call)
+{
+ unsigned nconds = 0;
+ auto_vec<gimple *, 12> conds;
+ gen_shrink_wrap_conditions (call, conds, &nconds);
+ if (nconds == 0 && !edom_only_function (call))
+ return false;
+
+ internal_fn ifn = replacement_internal_fn (call);
+ gcc_assert (ifn != IFN_LAST);
+
+ /* Construct the new call, with the same arguments as the original one. */
+ auto_vec <tree, 16> args;
+ unsigned int nargs = gimple_call_num_args (call);
+ for (unsigned int i = 0; i < nargs; ++i)
+ args.safe_push (gimple_call_arg (call, i));
+ gcall *new_call = gimple_build_call_internal_vec (ifn, args);
+ gimple_set_location (new_call, gimple_location (call));
+
+ /* Transfer the LHS to the new call. */
+ tree lhs = gimple_call_lhs (call);
+ gimple_call_set_lhs (new_call, lhs);
+ gimple_call_set_lhs (call, NULL_TREE);
+ SSA_NAME_DEF_STMT (lhs) = new_call;
+
+ /* Insert the new call. */
+ gimple_stmt_iterator gsi = gsi_for_stmt (call);
+ gsi_insert_before (&gsi, new_call, GSI_SAME_STMT);
+
+ if (nconds == 0)
+ {
+ /* Skip the call if LHS == LHS. If we reach here, EDOM is the only
+ valid errno value and it is used iff the result is NaN. */
+ conds.quick_push (gimple_build_cond (EQ_EXPR, lhs, lhs,
+ NULL_TREE, NULL_TREE));
+ nconds++;
+
+ /* Try replacing the original call with a direct assignment to
+ errno, via an internal function. */
+ if (set_edom_supported_p () && !stmt_ends_bb_p (call))
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (call);
+ gcall *new_call = gimple_build_call_internal (IFN_SET_EDOM, 0);
+ gimple_set_vuse (new_call, gimple_vuse (call));
+ gimple_set_vdef (new_call, gimple_vdef (call));
+ SSA_NAME_DEF_STMT (gimple_vdef (new_call)) = new_call;
+ gimple_set_location (new_call, gimple_location (call));
+ gsi_replace (&gsi, new_call, false);
+ call = new_call;
+ }
+ }
+
+ if (!shrink_wrap_one_built_in_call_with_conds (call, conds, nconds))
+ /* It's too late to back out now. */
+ gcc_unreachable ();
+ return true;
+}
+
/* The top level function for conditional dead code shrink
wrapping transformation. */
for (; i < n ; i++)
{
gcall *bi_call = calls[i];
- changed |= shrink_wrap_one_built_in_call (bi_call);
+ if (gimple_call_lhs (bi_call))
+ changed |= use_internal_fn (bi_call);
+ else
+ changed |= shrink_wrap_one_built_in_call (bi_call);
}
return changed;
{}
/* opt_pass methods: */
- virtual bool gate (function *fun)
+ virtual bool gate (function *)
{
/* The limit constants used in the implementation
assume IEEE floating point format. Other formats
can be supported in the future if needed. */
- return flag_tree_builtin_call_dce != 0
- && optimize_function_for_speed_p (fun);
+ return flag_tree_builtin_call_dce != 0;
}
virtual unsigned int execute (function *);
auto_vec<gcall *> cond_dead_built_in_calls;
FOR_EACH_BB_FN (bb, fun)
{
+ /* Skip blocks that are being optimized for size, since our
+ transformation always increases code size. */
+ if (optimize_bb_for_size_p (bb))
+ continue;
+
/* Collect dead call candidates. */
for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
{
gcall *stmt = dyn_cast <gcall *> (gsi_stmt (i));
- if (stmt && is_call_dce_candidate (stmt))
+ if (stmt
+ && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)
+ && (gimple_call_lhs (stmt)
+ ? can_use_internal_fn (stmt)
+ : can_test_argument_range (stmt)))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
projects / thirdparty / gcc.git / commitdiff
