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re PR target/82981 (unnecessary __multi3 call for mips64r6 linux kernel)

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PR target/82981
	* internal-fn.c: Include gimple-ssa.h, tree-phinodes.h and
	ssa-iterators.h.
	(can_widen_mult_without_libcall): New function.
	(expand_mul_overflow): If only checking unsigned mul overflow,
	not result, and can do efficiently MULT_HIGHPART_EXPR, emit that.
	Don't use WIDEN_MULT_EXPR if it would involve a libcall, unless
	no other way works.  Add MULT_HIGHPART_EXPR + MULT_EXPR support.
	(expand_DIVMOD): Formatting fix.
	* expmed.h (expand_mult): Add NO_LIBCALL argument.
	* expmed.c (expand_mult): Likewise.  Use OPTAB_WIDEN rather
	than OPTAB_LIB_WIDEN if NO_LIBCALL is true, and allow it to fail.

	* gcc.target/mips/pr82981.c: New test.

From-SVN: r254758
This commit is contained in:
Jakub Jelinek 2017-11-15 10:01:42 +01:00 committed by Jakub Jelinek
parent 65205a116a
commit 0b99f25372
6 changed files with 126 additions and 7 deletions
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13
gcc/ChangeLog
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@ -1,5 +1,18 @@
2017-11-15 Jakub Jelinek <jakub@redhat.com>
PR target/82981
* internal-fn.c: Include gimple-ssa.h, tree-phinodes.h and
ssa-iterators.h.
(can_widen_mult_without_libcall): New function.
(expand_mul_overflow): If only checking unsigned mul overflow,
not result, and can do efficiently MULT_HIGHPART_EXPR, emit that.
Don't use WIDEN_MULT_EXPR if it would involve a libcall, unless
no other way works. Add MULT_HIGHPART_EXPR + MULT_EXPR support.
(expand_DIVMOD): Formatting fix.
* expmed.h (expand_mult): Add NO_LIBCALL argument.
* expmed.c (expand_mult): Likewise. Use OPTAB_WIDEN rather
than OPTAB_LIB_WIDEN if NO_LIBCALL is true, and allow it to fail.
PR tree-optimization/82977
* tree-ssa-strlen.c (strlen_optimize_stmt): Pass a reference to a copy
constructed temporary to strlen_to_stridx.put.

10
gcc/expmed.c
View File

@ -3284,7 +3284,7 @@ expand_mult_const (machine_mode mode, rtx op0, HOST_WIDE_INT val,
rtx
expand_mult (machine_mode mode, rtx op0, rtx op1, rtx target,
int unsignedp)
int unsignedp, bool no_libcall)
{
enum mult_variant variant;
struct algorithm algorithm;
@ -3420,14 +3420,16 @@ expand_mult (machine_mode mode, rtx op0, rtx op1, rtx target,
{
op0 = force_reg (GET_MODE (op0), op0);
return expand_binop (mode, add_optab, op0, op0,
target, unsignedp, OPTAB_LIB_WIDEN);
target, unsignedp,
no_libcall ? OPTAB_WIDEN : OPTAB_LIB_WIDEN);
}
/* This used to use umul_optab if unsigned, but for non-widening multiply
there is no difference between signed and unsigned. */
op0 = expand_binop (mode, do_trapv ? smulv_optab : smul_optab,
op0, op1, target, unsignedp, OPTAB_LIB_WIDEN);
gcc_assert (op0);
op0, op1, target, unsignedp,
no_libcall ? OPTAB_WIDEN : OPTAB_LIB_WIDEN);
gcc_assert (op0 || no_libcall);
return op0;
}

2
gcc/expmed.h
View File

@ -727,7 +727,7 @@ extern rtx extract_bit_field (rtx, unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT, int, rtx,
machine_mode, machine_mode, bool, rtx *);
extern rtx extract_low_bits (machine_mode, machine_mode, rtx);
extern rtx expand_mult (machine_mode, rtx, rtx, rtx, int);
extern rtx expand_mult (machine_mode, rtx, rtx, rtx, int, bool = false);
extern rtx expand_mult_highpart_adjust (scalar_int_mode, rtx, rtx, rtx,
rtx, int);

90
gcc/internal-fn.c
View File

@ -46,6 +46,9 @@ along with GCC; see the file COPYING3. If not see
#include "recog.h"
#include "builtins.h"
#include "optabs-tree.h"
#include "gimple-ssa.h"
#include "tree-phinodes.h"
#include "ssa-iterators.h"
/* The names of each internal function, indexed by function number. */
const char *const internal_fn_name_array[] = {
@ -1172,6 +1175,35 @@ expand_neg_overflow (location_t loc, tree lhs, tree arg1, bool is_ubsan,
}
}
/* Return true if UNS WIDEN_MULT_EXPR with result mode WMODE and operand
mode MODE can be expanded without using a libcall. */
static bool
can_widen_mult_without_libcall (scalar_int_mode wmode, scalar_int_mode mode,
rtx op0, rtx op1, bool uns)
{
if (find_widening_optab_handler (umul_widen_optab, wmode, mode)
!= CODE_FOR_nothing)
return true;
if (find_widening_optab_handler (smul_widen_optab, wmode, mode)
!= CODE_FOR_nothing)
return true;
rtx_insn *last = get_last_insn ();
if (CONSTANT_P (op0))
op0 = convert_modes (wmode, mode, op0, uns);
else
op0 = gen_raw_REG (wmode, LAST_VIRTUAL_REGISTER + 1);
if (CONSTANT_P (op1))
op1 = convert_modes (wmode, mode, op1, uns);
else
op1 = gen_raw_REG (wmode, LAST_VIRTUAL_REGISTER + 2);
rtx ret = expand_mult (wmode, op0, op1, NULL_RTX, uns, true);
delete_insns_since (last);
return ret != NULL_RTX;
}
/* Add mul overflow checking to the statement STMT. */
static void
@ -1465,9 +1497,29 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
ops.op1 = make_tree (type, op1);
ops.op2 = NULL_TREE;
ops.location = loc;
/* Optimize unsigned overflow check where we don't use the
multiplication result, just whether overflow happened.
If we can do MULT_HIGHPART_EXPR, that followed by
comparison of the result against zero is cheapest.
We'll still compute res, but it should be DCEd later. */
use_operand_p use;
gimple *use_stmt;
if (!is_ubsan
&& lhs
&& uns
&& !(uns0_p && uns1_p && !unsr_p)
&& can_mult_highpart_p (mode, uns) == 1
&& single_imm_use (lhs, &use, &use_stmt)
&& is_gimple_assign (use_stmt)
&& gimple_assign_rhs_code (use_stmt) == IMAGPART_EXPR)
goto highpart;
if (GET_MODE_2XWIDER_MODE (mode).exists (&wmode)
&& targetm.scalar_mode_supported_p (wmode))
&& targetm.scalar_mode_supported_p (wmode)
&& can_widen_mult_without_libcall (wmode, mode, op0, op1, uns))
{
twoxwider:
ops.code = WIDEN_MULT_EXPR;
ops.type
= build_nonstandard_integer_type (GET_MODE_PRECISION (wmode), uns);
@ -1495,6 +1547,35 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
profile_probability::very_likely ());
}
}
else if (can_mult_highpart_p (mode, uns) == 1)
{
highpart:
ops.code = MULT_HIGHPART_EXPR;
ops.type = type;
rtx hipart = expand_expr_real_2 (&ops, NULL_RTX, mode,
EXPAND_NORMAL);
ops.code = MULT_EXPR;
res = expand_expr_real_2 (&ops, NULL_RTX, mode, EXPAND_NORMAL);
if (uns)
/* For the unsigned multiplication, there was overflow if
HIPART is non-zero. */
do_compare_rtx_and_jump (hipart, const0_rtx, EQ, true, mode,
NULL_RTX, NULL, done_label,
profile_probability::very_likely ());
else
{
rtx signbit = expand_shift (RSHIFT_EXPR, mode, res, prec - 1,
NULL_RTX, 0);
/* RES is low half of the double width result, HIPART
the high half. There was overflow if
HIPART is different from RES < 0 ? -1 : 0. */
do_compare_rtx_and_jump (signbit, hipart, EQ, true, mode,
NULL_RTX, NULL, done_label,
profile_probability::very_likely ());
}
}
else if (int_mode_for_size (prec / 2, 1).exists (&hmode)
&& 2 * GET_MODE_PRECISION (hmode) == prec)
{
@ -1800,6 +1881,11 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
tem = expand_expr_real_2 (&ops, NULL_RTX, mode, EXPAND_NORMAL);
emit_move_insn (res, tem);
}
else if (GET_MODE_2XWIDER_MODE (mode).exists (&wmode)
&& targetm.scalar_mode_supported_p (wmode))
/* Even emitting a libcall is better than not detecting overflow
at all. */
goto twoxwider;
else
{
gcc_assert (!is_ubsan);
@ -2588,7 +2674,7 @@ expand_DIVMOD (internal_fn, gcall *call_stmt)
expand_expr (build2 (COMPLEX_EXPR, TREE_TYPE (lhs),
make_tree (TREE_TYPE (arg0), quotient),
make_tree (TREE_TYPE (arg1), remainder)),
target, VOIDmode, EXPAND_NORMAL);
target, VOIDmode, EXPAND_NORMAL);
}
/* Expand a call to FN using the operands in STMT. FN has a single

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-11-15 Jakub Jelinek <jakub@redhat.com>
PR target/82981
* gcc.target/mips/pr82981.c: New test.
2017-11-15 Martin Liska <mliska@suse.cz>
* g++.dg/ubsan/vptr-12.C: New test.

13
gcc/testsuite/gcc.target/mips/pr82981.c Normal file
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@ -0,0 +1,13 @@
/* PR target/82981 */
/* { dg-do compile } */
/* { dg-skip-if "" { *-*-* } { "*" } { "-O2" } } */
/* { dg-options "-march=mips64r6 -mabi=64 -mexplicit-relocs" } */
unsigned long
func (unsigned long a, unsigned long b)
{
return a > (~0UL) / b;
}
/* { dg-final { scan-assembler-not "__multi3" } } */
/* { dg-final { scan-assembler "\tdmuhu" } } */