| Message ID | af73a46c-7c35-0f69-5c14-c030721bb653@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v4] vect: Recog mul_highpart pattern | expand |
On Fri, Jul 16, 2021 at 7:33 AM Kewen.Lin <linkw@linux.ibm.com> wrote: > > on 2021/7/15 下午7:58, Richard Biener wrote: > > On Thu, Jul 15, 2021 at 10:41 AM Kewen.Lin <linkw@linux.ibm.com> wrote: > >> > >> on 2021/7/15 下午4:04, Kewen.Lin via Gcc-patches wrote: > >>> Hi Uros, > >>> > >>> on 2021/7/15 下午3:17, Uros Bizjak wrote: > >>>> On Thu, Jul 15, 2021 at 9:07 AM Kewen.Lin <linkw@linux.ibm.com> wrote: > >>>>> > >>>>> 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 <linkw@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 <linkw@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 > >>>> > >>>> These XFAILs should be removed after your patch. > >>>> > >>> I'm curious whether it's intentional not to specify -fno-vect-cost-model > >>> for this test case. As noted above, this case is sensitive on how we > >>> cost mult_highpart. Without cost modeling, the XFAILs can be removed > >>> only with this mul_highpart pattern support, no matter how we model it > >>> (x86 part of this patch exists or not). > >>> > >>>> This is PR100696 [1], we want PMULH.W here, so x86 part of the patch > >>>> is actually not needed. > >>>> > >>> > >>> Thanks for the information! The justification for the x86 part is that: > >>> the IFN_MULH essentially covers MULT_HIGHPART_EXPR with mul_highpart > >>> optab support, i386 port has already customized costing for > >>> MULT_HIGHPART_EXPR (should mean/involve the case with mul_highpart optab > >>> support), if we don't follow the same way for IFN_MULH, I'm worried that > >>> we may cost the IFN_MULH wrongly. If taking IFN_MULH as normal stmt is > >>> a right thing (we shouldn't cost it specially), it at least means we > >>> have to adjust ix86_multiplication_cost for MULT_HIGHPART_EXPR when it > >>> has direct mul_highpart optab support, I think they should be costed > >>> consistently. Does it sound reasonable? > >>> > >> > >> Hi Richard(s), > >> > >> This possibly inconsistent handling problem seems like a counter example > >> better to use a new IFN rather than the existing tree_code, it seems hard > >> to maintain (should remember to keep consistent for its handlings). ;) > >> From this perspective, maybe it's better to move backward to use tree_code > >> and guard it under can_mult_highpart_p == 1 (just like IFN and avoid > >> costing issue Richi pointed out before)? > >> > >> What do you think? > > > > No, whenever we want to do code generation based on machine > > capabilities the canonical way to test for those is to look at optabs > > and then it's most natural to keep that 1:1 relation and emit > > internal function calls which directly map to supported optabs > > instead of going back to some tree codes. > > > > When targets "lie" and provide expanders for something they can > > only emulate then they have to compensate in their costing. > > But as I understand this isn't the case for x86 here. > > > > Now, in this case we already have the MULT_HIGHPART_EXPR tree, > > so yes, it might make sense to use that instead of introducing an > > alternate way via the direct internal function. Somebody decided > > that MULT_HIGHPART is generic enough to warrant this - but I > > see that expand_mult_highpart can fail unless can_mult_highpart_p > > and this is exactly one of the cases we want to avoid - either > > we can handle something generally in which case it can be a > > tree code or we can't, then it should be 1:1 tied to optabs at best > > (mult_highpart has scalar support only for the direct optab, > > vector support also for widen_mult). > > > > Thanks for the detailed explanation! The attached v4 follows the > preferred IFN way like v3, just with extra test case updates. > > Bootstrapped & regtested again on powerpc64le-linux-gnu P9, > x86_64-redhat-linux and aarch64-linux-gnu. > > Is it ok for trunk? OK. Thanks, Richard. > BR, > Kewen > ----- > gcc/ChangeLog: > > PR tree-optimization/100696 > * 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/testsuite/ChangeLog: > > PR tree-optimization/100696 > * gcc.target/i386/pr100637-3w.c: Adjust for mul_highpart recog.
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/testsuite/gcc.target/i386/pr100637-3w.c b/gcc/testsuite/gcc.target/i386/pr100637-3w.c index b951f30f571..4ea467b4af5 100644 --- a/gcc/testsuite/gcc.target/i386/pr100637-3w.c +++ b/gcc/testsuite/gcc.target/i386/pr100637-3w.c @@ -1,6 +1,6 @@ /* PR target/100637 */ /* { dg-do compile } */ -/* { dg-options "-O2 -ftree-vectorize -msse4" } */ +/* { dg-options "-O2 -ftree-vectorize -msse4 -fno-vect-cost-model" } */ short r[2], a[2], b[2]; unsigned short ur[2], ua[2], ub[2]; @@ -13,7 +13,7 @@ void mulh (void) r[i] = ((int) a[i] * b[i]) >> 16; } -/* { dg-final { scan-assembler "pmulhw" { xfail *-*-* } } } */ +/* { dg-final { scan-assembler "pmulhw" } } */ void mulhu (void) { @@ -23,7 +23,7 @@ void mulhu (void) ur[i] = ((unsigned int) ua[i] * ub[i]) >> 16; } -/* { dg-final { scan-assembler "pmulhuw" { xfail *-*-* } } } */ +/* { dg-final { scan-assembler "pmulhuw" } } */ void mulhrs (void) { 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];