On Sep 13, 2017, at 7:23 AM, Richard Biener <richard.guent...@gmail.com> wrote:
>
> On Tue, Sep 12, 2017 at 11:08 PM, Will Schmidt
> <will_schm...@vnet.ibm.com> wrote:
>> Hi,
>>
>> [PATCH, rs6000] [v2] Folding of vector loads in GIMPLE
>>
>> Folding of vector loads in GIMPLE.
>>
>> Add code to handle gimple folding for the vec_ld builtins.
>> Remove the now obsoleted folding code for vec_ld from rs6000-c.c. Surrounding
>> comments have been adjusted slightly so they continue to read OK for the
>> existing vec_st code.
>>
>> The resulting code is specifically verified by the powerpc/fold-vec-ld-*.c
>> tests which have been posted separately.
>>
>> For V2 of this patch, I've removed the chunk of code that prohibited the
>> gimple fold from occurring in BE environments. This had fixed an issue
>> for me earlier during my development of the code, and turns out this was
>> not necessary. I've sniff-tested after removing that check and it looks
>> OK.
>>
>>> + /* Limit folding of loads to LE targets. */
>>> + if (BYTES_BIG_ENDIAN || VECTOR_ELT_ORDER_BIG)
>>> + return false;
>>
>> I've restarted a regression test on this updated version.
>>
>> OK for trunk (assuming successful regression test completion) ?
>>
>> Thanks,
>> -Will
>>
>> [gcc]
>>
>> 2017-09-12 Will Schmidt <will_schm...@vnet.ibm.com>
>>
>> * config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add handling
>> for early folding of vector loads (ALTIVEC_BUILTIN_LVX_*).
>> * config/rs6000/rs6000-c.c (altivec_resolve_overloaded_builtin):
>> Remove obsoleted code for handling ALTIVEC_BUILTIN_VEC_LD.
>>
>> diff --git a/gcc/config/rs6000/rs6000-c.c b/gcc/config/rs6000/rs6000-c.c
>> index fbab0a2..bb8a77d 100644
>> --- a/gcc/config/rs6000/rs6000-c.c
>> +++ b/gcc/config/rs6000/rs6000-c.c
>> @@ -6470,92 +6470,19 @@ altivec_resolve_overloaded_builtin (location_t loc,
>> tree fndecl,
>> convert (TREE_TYPE (stmt), arg0));
>> stmt = build2 (COMPOUND_EXPR, arg1_type, stmt, decl);
>> return stmt;
>> }
>>
>> - /* Expand vec_ld into an expression that masks the address and
>> - performs the load. We need to expand this early to allow
>> + /* Expand vec_st into an expression that masks the address and
>> + performs the store. We need to expand this early to allow
>> the best aliasing, as by the time we get into RTL we no longer
>> are able to honor __restrict__, for example. We may want to
>> consider this for all memory access built-ins.
>>
>> When -maltivec=be is specified, or the wrong number of arguments
>> is provided, simply punt to existing built-in processing. */
>> - if (fcode == ALTIVEC_BUILTIN_VEC_LD
>> - && (BYTES_BIG_ENDIAN || !VECTOR_ELT_ORDER_BIG)
>> - && nargs == 2)
>> - {
>> - tree arg0 = (*arglist)[0];
>> - tree arg1 = (*arglist)[1];
>> -
>> - /* Strip qualifiers like "const" from the pointer arg. */
>> - tree arg1_type = TREE_TYPE (arg1);
>> - if (!POINTER_TYPE_P (arg1_type) && TREE_CODE (arg1_type) !=
>> ARRAY_TYPE)
>> - goto bad;
>> -
>> - tree inner_type = TREE_TYPE (arg1_type);
>> - if (TYPE_QUALS (TREE_TYPE (arg1_type)) != 0)
>> - {
>> - arg1_type = build_pointer_type (build_qualified_type (inner_type,
>> - 0));
>> - arg1 = fold_convert (arg1_type, arg1);
>> - }
>> -
>> - /* Construct the masked address. Let existing error handling take
>> - over if we don't have a constant offset. */
>> - arg0 = fold (arg0);
>> -
>> - if (TREE_CODE (arg0) == INTEGER_CST)
>> - {
>> - if (!ptrofftype_p (TREE_TYPE (arg0)))
>> - arg0 = build1 (NOP_EXPR, sizetype, arg0);
>> -
>> - tree arg1_type = TREE_TYPE (arg1);
>> - if (TREE_CODE (arg1_type) == ARRAY_TYPE)
>> - {
>> - arg1_type = TYPE_POINTER_TO (TREE_TYPE (arg1_type));
>> - tree const0 = build_int_cstu (sizetype, 0);
>> - tree arg1_elt0 = build_array_ref (loc, arg1, const0);
>> - arg1 = build1 (ADDR_EXPR, arg1_type, arg1_elt0);
>> - }
>> -
>> - tree addr = fold_build2_loc (loc, POINTER_PLUS_EXPR, arg1_type,
>> - arg1, arg0);
>> - tree aligned = fold_build2_loc (loc, BIT_AND_EXPR, arg1_type, addr,
>> - build_int_cst (arg1_type, -16));
>> -
>> - /* Find the built-in to get the return type so we can convert
>> - the result properly (or fall back to default handling if the
>> - arguments aren't compatible). */
>> - for (desc = altivec_overloaded_builtins;
>> - desc->code && desc->code != fcode; desc++)
>> - continue;
>> -
>> - for (; desc->code == fcode; desc++)
>> - if (rs6000_builtin_type_compatible (TREE_TYPE (arg0), desc->op1)
>> - && (rs6000_builtin_type_compatible (TREE_TYPE (arg1),
>> - desc->op2)))
>> - {
>> - tree ret_type = rs6000_builtin_type (desc->ret_type);
>> - if (TYPE_MODE (ret_type) == V2DImode)
>> - /* Type-based aliasing analysis thinks vector long
>> - and vector long long are different and will put them
>> - in distinct alias classes. Force our return type
>> - to be a may-alias type to avoid this. */
>> - ret_type
>> - = build_pointer_type_for_mode (ret_type, Pmode,
>> - true/*can_alias_all*/);
>> - else
>> - ret_type = build_pointer_type (ret_type);
>> - aligned = build1 (NOP_EXPR, ret_type, aligned);
>> - tree ret_val = build_indirect_ref (loc, aligned, RO_NULL);
>> - return ret_val;
>> - }
>> - }
>> - }
>>
>> - /* Similarly for stvx. */
>> if (fcode == ALTIVEC_BUILTIN_VEC_ST
>> && (BYTES_BIG_ENDIAN || !VECTOR_ELT_ORDER_BIG)
>> && nargs == 3)
>> {
>> tree arg0 = (*arglist)[0];
>> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
>> index 1338371..1fb5f44 100644
>> --- a/gcc/config/rs6000/rs6000.c
>> +++ b/gcc/config/rs6000/rs6000.c
>> @@ -16547,10 +16547,61 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator
>> *gsi)
>> res = gimple_build (&stmts, VIEW_CONVERT_EXPR, TREE_TYPE (lhs), res);
>> gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
>> update_call_from_tree (gsi, res);
>> return true;
>> }
>> + /* Vector loads. */
>> + case ALTIVEC_BUILTIN_LVX_V16QI:
>> + case ALTIVEC_BUILTIN_LVX_V8HI:
>> + case ALTIVEC_BUILTIN_LVX_V4SI:
>> + case ALTIVEC_BUILTIN_LVX_V4SF:
>> + case ALTIVEC_BUILTIN_LVX_V2DI:
>> + case ALTIVEC_BUILTIN_LVX_V2DF:
>> + {
>> + gimple *g;
>> + arg0 = gimple_call_arg (stmt, 0); // offset
>> + arg1 = gimple_call_arg (stmt, 1); // address
>> +
>> + lhs = gimple_call_lhs (stmt);
>> + location_t loc = gimple_location (stmt);
>> +
>> + tree arg1_type = TREE_TYPE (arg1);
>> + tree lhs_type = TREE_TYPE (lhs);
>> +
>> + /* POINTER_PLUS_EXPR wants the offset to be of type 'sizetype'.
>> Create
>> + the tree using the value from arg0. The resulting type will
>> match
>> + the type of arg1. */
>> + tree temp_offset = create_tmp_reg_or_ssa_name (sizetype);
>> + g = gimple_build_assign (temp_offset, NOP_EXPR, arg0);
>> + gimple_set_location (g, loc);
>> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
>> + tree temp_addr = create_tmp_reg_or_ssa_name (arg1_type);
>> + g = gimple_build_assign (temp_addr, POINTER_PLUS_EXPR, arg1,
>> + temp_offset);
>> + gimple_set_location (g, loc);
>> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
>> +
>> + /* Mask off any lower bits from the address. */
>> + tree alignment_mask = build_int_cst (arg1_type, -16);
>> + tree aligned_addr = create_tmp_reg_or_ssa_name (arg1_type);
>> + g = gimple_build_assign (aligned_addr, BIT_AND_EXPR,
>> + temp_addr, alignment_mask);
>> + gimple_set_location (g, loc);
>> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
>
> You could use
>
> gimple_seq stmts = NULL;
> tree temp_offset = gimple_convert (&stmts, loc, sizetype, arg0);
> tree temp_addr = gimple_build (&stmts, loc, POINTER_PLUS_EXPR,
> arg1_type, arg1, temp_offset);
> tree aligned_addr = gimple_build (&stmts, loc, BIT_AND_EXPR,
> arg1_type, temp_addr, build_int_cst (arg1_type, -16));
> gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
>
>> + /* Use the build2 helper to set up the mem_ref. The MEM_REF could
>> also
>> + take an offset, but since we've already incorporated the offset
>> + above, here we just pass in a zero. */
>> + g = gimple_build_assign (lhs, build2 (MEM_REF, lhs_type,
>> aligned_addr,
>> + build_int_cst (arg1_type,
>> 0)));
>
> are you sure about arg1_type here? I'm sure not. For
>
> ... foo (struct S *p)
> {
> return __builtin_lvx_v2df (4, (double *)p);
> }
>
> you'd end up with p as arg1 and thus struct S * as arg1_type and thus
> TBAA using 'struct S' to access the memory.
Hm, is that so? Wouldn't arg1_type be double* since arg1 is (double *)p?
Will, you should probably test this example and see, but I'm pretty confident
about this (see below).
>
> I think if the builtins have any TBAA constraints you need to build those
> explicitely, if not, you should use ptr_type_node aka no TBAA.
The type signatures are constrained during parsing, so we should only
see allowed pointer types on arg1 by the time we get to gimple folding. I
think that using arg1_type should work, but I am probably missing
something subtle, so please feel free to whack me on the temple until
I get it. :-)
Bill
>
> Richard.
>
>> + gimple_set_location (g, loc);
>> + gsi_replace (gsi, g, true);
>> +
>> + return true;
>> +
>> + }
>> +
>> default:
>> if (TARGET_DEBUG_BUILTIN)
>> fprintf (stderr, "gimple builtin intrinsic not matched:%d %s %s\n",
>> fn_code, fn_name1, fn_name2);
>> break;
