Ping
On 28/11/23 6:24 pm, Surya Kumari Jangala wrote:
> Ping
>
> On 10/11/23 12:27 pm, Surya Kumari Jangala wrote:
>> Ping
>>
>> On 03/11/23 1:14 pm, Surya Kumari Jangala wrote:
>>> Hi Segher,
>>> I have incorporated changes in the code as per the review comments provided
>>> by you
>>> for version 2 of the patch. Please review.
>>>
>>> Regards,
>>> Surya
>>>
>>>
>>> rs6000/p8swap: Fix incorrect lane extraction by vec_extract() [PR106770]
>>>
>>> In the routine rs6000_analyze_swaps(), special handling of swappable
>>> instructions is done even if the webs that contain the swappable
>>> instructions
>>> are not optimized, i.e., the webs do not contain any permuting load/store
>>> instructions along with the associated register swap instructions. Doing
>>> special
>>> handling in such webs will result in the extracted lane being adjusted
>>> unnecessarily for vec_extract.
>>>
>>> Another issue is that existing code treats non-permuting loads/stores as
>>> special
>>> swappables. Non-permuting loads/stores (that have not yet been split into a
>>> permuting load/store and a swap) are handled by converting them into a
>>> permuting
>>> load/store (which effectively removes the swap). As a result, if special
>>> swappables are handled only in webs containing permuting loads/stores, then
>>> non-optimal code is generated for non-permuting loads/stores.
>>>
>>> Hence, in this patch, all webs containing either permuting loads/ stores or
>>> non-permuting loads/stores are marked as requiring special handling of
>>> swappables. Swaps associated with permuting loads/stores are marked for
>>> removal,
>>> and non-permuting loads/stores are converted to permuting loads/stores.
>>> Then the
>>> special swappables in the webs are fixed up.
>>>
>>> This patch also ensures that swappable instructions are not modified in the
>>> following webs as it is incorrect to do so:
>>> - webs containing permuting load/store instructions and associated swap
>>> instructions that are transformed by converting the permuting memory
>>> instructions into non-permuting instructions and removing the swap
>>> instructions.
>>> - webs where swap(load(vector constant)) instructions are replaced with
>>> load(swapped vector constant).
>>>
>>> 2023-09-10 Surya Kumari Jangala <jskum...@linux.ibm.com>
>>>
>>> gcc/
>>> PR rtl-optimization/PR106770
>>> * config/rs6000/rs6000-p8swap.cc (non_permuting_mem_insn): New function.
>>> (handle_non_permuting_mem_insn): New function.
>>> (rs6000_analyze_swaps): Handle swappable instructions only in certain
>>> webs.
>>> (web_requires_special_handling): New instance variable.
>>> (handle_special_swappables): Remove handling of non-permuting load/store
>>> instructions.
>>>
>>> gcc/testsuite/
>>> PR rtl-optimization/PR106770
>>> * gcc.target/powerpc/pr106770.c: New test.
>>> ---
>>>
>>> diff --git a/gcc/config/rs6000/rs6000-p8swap.cc
>>> b/gcc/config/rs6000/rs6000-p8swap.cc
>>> index 0388b9bd736..02ea299bc3d 100644
>>> --- a/gcc/config/rs6000/rs6000-p8swap.cc
>>> +++ b/gcc/config/rs6000/rs6000-p8swap.cc
>>> @@ -179,6 +179,13 @@ class swap_web_entry : public web_entry_base
>>> unsigned int special_handling : 4;
>>> /* Set if the web represented by this entry cannot be optimized. */
>>> unsigned int web_not_optimizable : 1;
>>> + /* Set if the swappable insns in the web represented by this entry
>>> + have to be fixed. Swappable insns have to be fixed in:
>>> + - webs containing permuting loads/stores and the swap insns
>>> + in such webs have been marked for removal
>>> + - webs where non-permuting loads/stores have been converted
>>> + to permuting loads/stores */
>>> + unsigned int web_requires_special_handling : 1;
>>> /* Set if this insn should be deleted. */
>>> unsigned int will_delete : 1;
>>> };
>>> @@ -1468,14 +1475,6 @@ handle_special_swappables (swap_web_entry
>>> *insn_entry, unsigned i)
>>> if (dump_file)
>>> fprintf (dump_file, "Adjusting subreg in insn %d\n", i);
>>> break;
>>> - case SH_NOSWAP_LD:
>>> - /* Convert a non-permuting load to a permuting one. */
>>> - permute_load (insn);
>>> - break;
>>> - case SH_NOSWAP_ST:
>>> - /* Convert a non-permuting store to a permuting one. */
>>> - permute_store (insn);
>>> - break;
>>> case SH_EXTRACT:
>>> /* Change the lane on an extract operation. */
>>> adjust_extract (insn);
>>> @@ -2401,6 +2400,25 @@ recombine_lvx_stvx_patterns (function *fun)
>>> free (to_delete);
>>> }
>>>
>>> +/* Return true if insn is a non-permuting load/store. */
>>> +static bool
>>> +non_permuting_mem_insn (swap_web_entry *insn_entry, unsigned int i)
>>> +{
>>> + return insn_entry[i].special_handling == SH_NOSWAP_LD
>>> + || insn_entry[i].special_handling == SH_NOSWAP_ST;
>>> +}
>>> +
>>> +/* Convert a non-permuting load/store insn to a permuting one. */
>>> +static void
>>> +convert_mem_insn (swap_web_entry *insn_entry, unsigned int i)
>>> +{
>>> + rtx_insn *insn = insn_entry[i].insn;
>>> + if (insn_entry[i].special_handling == SH_NOSWAP_LD)
>>> + permute_load (insn);
>>> + if (insn_entry[i].special_handling == SH_NOSWAP_ST)
>>> + permute_store (insn);
>>> +}
>>> +
>>> /* Main entry point for this pass. */
>>> unsigned int
>>> rs6000_analyze_swaps (function *fun)
>>> @@ -2624,25 +2642,55 @@ rs6000_analyze_swaps (function *fun)
>>> dump_swap_insn_table (insn_entry);
>>> }
>>>
>>> - /* For each load and store in an optimizable web (which implies
>>> - the loads and stores are permuting), find the associated
>>> - register swaps and mark them for removal. Due to various
>>> - optimizations we may mark the same swap more than once. Also
>>> - perform special handling for swappable insns that require it. */
>>> + /* There are two kinds of optimizations that can be performed on an
>>> + optimizable web:
>>> + 1. Remove the register swaps associated with permuting load/store
>>> + in an optimizable web
>>> + 2. Convert the vanilla loads/stores (that have not yet been split
>>> + into a permuting load/store and a swap) into a permuting
>>> + load/store (which effectively removes the swap)
>>> + In both the cases, swappable instructions in the webs need
>>> + special handling to fix them up. */
>>> for (i = 0; i < e; ++i)
>>> + /* For each permuting load/store in an optimizable web, find
>>> + the associated register swaps and mark them for removal.
>>> + Due to various optimizations we may mark the same swap more
>>> + than once. */
>>> if ((insn_entry[i].is_load || insn_entry[i].is_store)
>>> && insn_entry[i].is_swap)
>>> {
>>> swap_web_entry* root_entry
>>> = (swap_web_entry*)((&insn_entry[i])->unionfind_root ());
>>> if (!root_entry->web_not_optimizable)
>>> - mark_swaps_for_removal (insn_entry, i);
>>> + {
>>> + mark_swaps_for_removal (insn_entry, i);
>>> + root_entry->web_requires_special_handling = true;
>>> + }
>>> }
>>> - else if (insn_entry[i].is_swappable && insn_entry[i].special_handling)
>>> + /* Convert the non-permuting loads/stores into a permuting
>>> + load/store. */
>>> + else if (insn_entry[i].is_swappable
>>> + && non_permuting_mem_insn (insn_entry, i))
>>> {
>>> swap_web_entry* root_entry
>>> = (swap_web_entry*)((&insn_entry[i])->unionfind_root ());
>>> if (!root_entry->web_not_optimizable)
>>> + {
>>> + convert_mem_insn (insn_entry, i);
>>> + root_entry->web_requires_special_handling = true;
>>> + }
>>> + }
>>> +
>>> + /* Now that the webs which require special handling have been
>>> + identified, modify the instructions that are sensitive to
>>> + element order. */
>>> + for (i = 0; i < e; ++i)
>>> + if (insn_entry[i].is_swappable && insn_entry[i].special_handling
>>> + && !non_permuting_mem_insn (insn_entry, i))
>>> + {
>>> + swap_web_entry* root_entry
>>> + = (swap_web_entry*)((&insn_entry[i])->unionfind_root ());
>>> + if (root_entry->web_requires_special_handling)
>>> handle_special_swappables (insn_entry, i);
>>> }
>>>
>>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106770.c
>>> b/gcc/testsuite/gcc.target/powerpc/pr106770.c
>>> new file mode 100644
>>> index 00000000000..5b300b94a41
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.target/powerpc/pr106770.c
>>> @@ -0,0 +1,20 @@
>>> +/* { dg-require-effective-target powerpc_p8vector_ok } */
>>> +/* { dg-options "-mdejagnu-cpu=power8 -O2 " } */
>>> +/* The 2 xxpermdi instructions are generated by the two
>>> + calls to vec_promote() */
>>> +/* { dg-final { scan-assembler-times {xxpermdi} 2 } } */
>>> +
>>> +/* Test case to resolve PR106770 */
>>> +
>>> +#include <altivec.h>
>>> +
>>> +int cmp2(double a, double b)
>>> +{
>>> + vector double va = vec_promote(a, 1);
>>> + vector double vb = vec_promote(b, 1);
>>> + vector long long vlt = (vector long long)vec_cmplt(va, vb);
>>> + vector long long vgt = (vector long long)vec_cmplt(vb, va);
>>> + vector signed long long vr = vec_sub(vlt, vgt);
>>> +
>>> + return vec_extract(vr, 1);
>>> +}
