on 2021/7/14 下午3:45, Kewen.Lin via Gcc-patches wrote:
> on 2021/7/14 下午2:38, Richard Biener wrote:
>> On Tue, Jul 13, 2021 at 4:59 PM Kewen.Lin <li...@linux.ibm.com> wrote:
>>>
>>> on 2021/7/13 下午8:42, Richard Biener wrote:
>>>> On Tue, Jul 13, 2021 at 12:25 PM Kewen.Lin <li...@linux.ibm.com> wrote:
>>
>>> I guess the proposed IFN would be directly mapped for [us]mul_highpart?
>>
>> Yes.
>>
>
> Thanks for confirming! The related patch v2 is attached and the testing
> is ongoing.
>
It's bootstrapped & regtested on powerpc64le-linux-gnu P9 and
aarch64-linux-gnu. But on x86_64-redhat-linux there are XPASSes as below:
XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhuw
XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhuw
XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhw
XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhw
They weren't exposed in the testing run with the previous patch which
doesn't use IFN way. By investigating it, the difference comes from
the different costing on MULT_HIGHPART_EXPR and IFN_MULH.
For MULT_HIGHPART_EXPR, it's costed by 16 from below call:
case MULT_EXPR:
case WIDEN_MULT_EXPR:
case MULT_HIGHPART_EXPR:
stmt_cost = ix86_multiplication_cost (ix86_cost, mode);
While for IFN_MULH, it's costed by 4 as normal stmt so the total cost
becomes profitable and the expected vectorization happens.
One conservative fix seems to make IFN_MULH costing go through the
unique cost interface for multiplication, that is:
case CFN_MULH:
stmt_cost = ix86_multiplication_cost (ix86_cost, mode);
break;
As the test case marks the checks as "xfail", probably it's good to
revisit the costing on mul_highpart to ensure it's not priced more.
The attached patch also addressed Richard S.'s review comments on
two reformatting hunks. Is it ok for trunk?
BR,
Kewen
-----
gcc/ChangeLog:
* internal-fn.c (first_commutative_argument): Add info for IFN_MULH.
* internal-fn.def (IFN_MULH): New internal function.
* tree-vect-patterns.c (vect_recog_mulhs_pattern): Add support to
recog normal multiply highpart as IFN_MULH.
* config/i386/i386.c (ix86_add_stmt_cost): Adjust for combined
function CFN_MULH.
---
gcc/config/i386/i386.c | 3 +++
gcc/internal-fn.c | 1 +
gcc/internal-fn.def | 2 ++
gcc/tree-vect-patterns.c | 38 ++++++++++++++++++++++++++++----------
4 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index a93128fa0a4..1dd9108353c 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -22559,6 +22559,9 @@ ix86_add_stmt_cost (class vec_info *vinfo, void *data,
int count,
mode == SFmode ? ix86_cost->fmass
: ix86_cost->fmasd);
break;
+ case CFN_MULH:
+ stmt_cost = ix86_multiplication_cost (ix86_cost, mode);
+ break;
default:
break;
}
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index fb8b43d1ce2..b1b4289357c 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3703,6 +3703,7 @@ first_commutative_argument (internal_fn fn)
case IFN_FNMS:
case IFN_AVG_FLOOR:
case IFN_AVG_CEIL:
+ case IFN_MULH:
case IFN_MULHS:
case IFN_MULHRS:
case IFN_FMIN:
diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
index c3b8e730960..ed6d7de1680 100644
--- a/gcc/internal-fn.def
+++ b/gcc/internal-fn.def
@@ -169,6 +169,8 @@ DEF_INTERNAL_SIGNED_OPTAB_FN (AVG_FLOOR, ECF_CONST |
ECF_NOTHROW, first,
DEF_INTERNAL_SIGNED_OPTAB_FN (AVG_CEIL, ECF_CONST | ECF_NOTHROW, first,
savg_ceil, uavg_ceil, binary)
+DEF_INTERNAL_SIGNED_OPTAB_FN (MULH, ECF_CONST | ECF_NOTHROW, first,
+ smul_highpart, umul_highpart, binary)
DEF_INTERNAL_SIGNED_OPTAB_FN (MULHS, ECF_CONST | ECF_NOTHROW, first,
smulhs, umulhs, binary)
DEF_INTERNAL_SIGNED_OPTAB_FN (MULHRS, ECF_CONST | ECF_NOTHROW, first,
diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index b2e7fc2cc7a..ada89d7060b 100644
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -1896,8 +1896,15 @@ vect_recog_over_widening_pattern (vec_info *vinfo,
1) Multiply high with scaling
TYPE res = ((TYPE) a * (TYPE) b) >> c;
+ Here, c is bitsize (TYPE) / 2 - 1.
+
2) ... or also with rounding
TYPE res = (((TYPE) a * (TYPE) b) >> d + 1) >> 1;
+ Here, d is bitsize (TYPE) / 2 - 2.
+
+ 3) Normal multiply high
+ TYPE res = ((TYPE) a * (TYPE) b) >> e;
+ Here, e is bitsize (TYPE) / 2.
where only the bottom half of res is used. */
@@ -1942,7 +1949,6 @@ vect_recog_mulhs_pattern (vec_info *vinfo,
stmt_vec_info mulh_stmt_info;
tree scale_term;
internal_fn ifn;
- unsigned int expect_offset;
/* Check for the presence of the rounding term. */
if (gimple_assign_rhs_code (rshift_input_stmt) == PLUS_EXPR)
@@ -1991,25 +1997,37 @@ vect_recog_mulhs_pattern (vec_info *vinfo,
/* Get the scaling term. */
scale_term = gimple_assign_rhs2 (plus_input_stmt);
+ /* Check that the scaling factor is correct. */
+ if (TREE_CODE (scale_term) != INTEGER_CST)
+ return NULL;
+
+ /* Check pattern 2). */
+ if (wi::to_widest (scale_term) + target_precision + 2
+ != TYPE_PRECISION (lhs_type))
+ return NULL;
- expect_offset = target_precision + 2;
ifn = IFN_MULHRS;
}
else
{
mulh_stmt_info = rshift_input_stmt_info;
scale_term = gimple_assign_rhs2 (last_stmt);
+ /* Check that the scaling factor is correct. */
+ if (TREE_CODE (scale_term) != INTEGER_CST)
+ return NULL;
- expect_offset = target_precision + 1;
- ifn = IFN_MULHS;
+ /* Check for pattern 1). */
+ if (wi::to_widest (scale_term) + target_precision + 1
+ == TYPE_PRECISION (lhs_type))
+ ifn = IFN_MULHS;
+ /* Check for pattern 3). */
+ else if (wi::to_widest (scale_term) + target_precision
+ == TYPE_PRECISION (lhs_type))
+ ifn = IFN_MULH;
+ else
+ return NULL;
}
- /* Check that the scaling factor is correct. */
- if (TREE_CODE (scale_term) != INTEGER_CST
- || wi::to_widest (scale_term) + expect_offset
- != TYPE_PRECISION (lhs_type))
- return NULL;
-
/* Check whether the scaling input term can be seen as two widened
inputs multiplied together. */
vect_unpromoted_value unprom_mult[2];
--
2.17.1
