On 26 January 2018 at 11:25, Richard Biener <rguent...@suse.de> wrote:
> On Thu, 25 Jan 2018, Richard Biener wrote:
>
>> On Thu, 25 Jan 2018, Marc Glisse wrote:
>>
>> > On Thu, 25 Jan 2018, Richard Biener wrote:
>> >
>> > > --- gcc/match.pd (revision 257047)
>> > > +++ gcc/match.pd (working copy)
>> > > @@ -1939,6 +1939,37 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>> > > (minus (convert (view_convert:stype @1))
>> > > (convert (view_convert:stype @2)))))))
>> > >
>> > > +/* (A * C) +- (B * C) -> (A+-B) * C and (A * C) +- A -> A * (C+-1).
>> > > + Modeled after fold_plusminus_mult_expr. */
>> > > +(if (!TYPE_SATURATING (type)
>> > > + && (!FLOAT_TYPE_P (type) || flag_associative_math))
>> > > + (for plusminus (plus minus)
>> > > + (simplify
>> > > + (plusminus (mult:s @0 @1) (mult:cs @0 @2))
>> >
>> > No :c on the first mult, so we don't actually handle A*C+B*C?
>>
>> Hmm, I somehow convinced myself that it's only necessary on one
>> of the mults... but you are of course right. Will re-test with
>> that fixed.
>
> This is what I have applied. Note I had to XFAIL a minor part of
> gcc.dg/tree-ssa/loop-15.c, namely simplifying the final value
> replacement down to n * n. While the patch should enable this
> the place where the transform could trigger with enough information
> about n is VRP but that doesn't end up folding all stmts - and
> that's something I'm not willing to change right now.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, applied on trunk.
>
Hi,
I think this patch caused regressions on aarch64:
FAIL: gcc.dg/wmul-1.c scan-tree-dump-not widening_mul "WIDEN_MULT_PLUS_EXPR"
Thanks,
Christophe
> Richard.
>
> 2018-01-26 Richard Biener <rguent...@suse.de>
>
> PR tree-optimization/81082
> * fold-const.c (fold_plusminus_mult_expr): Do not perform the
> association if it requires casting to unsigned.
> * match.pd ((A * C) +- (B * C) -> (A+-B)): New patterns derived
> from fold_plusminus_mult_expr to catch important cases late when
> range info is available.
>
> * gcc.dg/vect/pr81082.c: New testcase.
> * gcc.dg/tree-ssa/loop-15.c: XFAIL the (int)((unsigned)n + -1U) * n +
> n
> simplification to n * n.
>
> Index: gcc/fold-const.c
> ===================================================================
> --- gcc/fold-const.c (revision 257047)
> +++ gcc/fold-const.c (working copy)
> @@ -7097,7 +7097,7 @@ fold_plusminus_mult_expr (location_t loc
>
> /* Same may be zero and thus the operation 'code' may overflow. Likewise
> same may be minus one and thus the multiplication may overflow. Perform
> - the operations in an unsigned type. */
> + the sum operation in an unsigned type. */
> tree utype = unsigned_type_for (type);
> tree tem = fold_build2_loc (loc, code, utype,
> fold_convert_loc (loc, utype, alt0),
> @@ -7110,9 +7110,9 @@ fold_plusminus_mult_expr (location_t loc
> return fold_build2_loc (loc, MULT_EXPR, type,
> fold_convert (type, tem), same);
>
> - return fold_convert_loc (loc, type,
> - fold_build2_loc (loc, MULT_EXPR, utype, tem,
> - fold_convert_loc (loc, utype,
> same)));
> + /* Do not resort to unsigned multiplication because
> + we lose the no-overflow property of the expression. */
> + return NULL_TREE;
> }
>
> /* Subroutine of native_encode_expr. Encode the INTEGER_CST
> Index: gcc/match.pd
> ===================================================================
> --- gcc/match.pd (revision 257047)
> +++ gcc/match.pd (working copy)
> @@ -1939,6 +1939,37 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (minus (convert (view_convert:stype @1))
> (convert (view_convert:stype @2)))))))
>
> +/* (A * C) +- (B * C) -> (A+-B) * C and (A * C) +- A -> A * (C+-1).
> + Modeled after fold_plusminus_mult_expr. */
> +(if (!TYPE_SATURATING (type)
> + && (!FLOAT_TYPE_P (type) || flag_associative_math))
> + (for plusminus (plus minus)
> + (simplify
> + (plusminus (mult:cs @0 @1) (mult:cs @0 @2))
> + (if (!ANY_INTEGRAL_TYPE_P (type)
> + || TYPE_OVERFLOW_WRAPS (type)
> + || (INTEGRAL_TYPE_P (type)
> + && tree_expr_nonzero_p (@0)
> + && expr_not_equal_to (@0, wi::minus_one (TYPE_PRECISION (type)))))
> + (mult (plusminus @1 @2) @0)))
> + /* We cannot generate constant 1 for fract. */
> + (if (!ALL_FRACT_MODE_P (TYPE_MODE (type)))
> + (simplify
> + (plusminus @0 (mult:cs @0 @2))
> + (if (!ANY_INTEGRAL_TYPE_P (type)
> + || TYPE_OVERFLOW_WRAPS (type)
> + || (INTEGRAL_TYPE_P (type)
> + && tree_expr_nonzero_p (@0)
> + && expr_not_equal_to (@0, wi::minus_one (TYPE_PRECISION
> (type)))))
> + (mult (plusminus { build_one_cst (type); } @2) @0)))
> + (simplify
> + (plusminus (mult:cs @0 @2) @0)
> + (if (!ANY_INTEGRAL_TYPE_P (type)
> + || TYPE_OVERFLOW_WRAPS (type)
> + || (INTEGRAL_TYPE_P (type)
> + && tree_expr_nonzero_p (@0)
> + && expr_not_equal_to (@0, wi::minus_one (TYPE_PRECISION
> (type)))))
> + (mult (plusminus @2 { build_one_cst (type); }) @0))))))
>
> /* Simplifications of MIN_EXPR, MAX_EXPR, fmin() and fmax(). */
>
> Index: gcc/testsuite/gcc.dg/vect/pr81082.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/vect/pr81082.c (revision 0)
> +++ gcc/testsuite/gcc.dg/vect/pr81082.c (working copy)
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-require-effective-target vect_int } */
> +
> +int
> +f (int *x, int b1, int b2, int b3)
> +{
> + int foo = 0;
> + for (int i1 = 0; i1 < b1; ++i1)
> + for (int i2 = 0; i2 < b2; ++i2)
> + for (int i3 = 0; i3 < b3; ++i3)
> + foo += x[i1 * b2 * b3 + i2 * b3 + (i3 - 1)];
> + return foo;
> +}
> +
> +/* { dg-final { scan-tree-dump "vectorized 1 loops in function" "vect" } } */
> Index: gcc/testsuite/gcc.dg/tree-ssa/loop-15.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/tree-ssa/loop-15.c (revision 257048)
> +++ gcc/testsuite/gcc.dg/tree-ssa/loop-15.c (working copy)
> @@ -19,7 +19,7 @@ int bla(void)
> }
>
> /* Since the loop is removed, there should be no addition. */
> -/* { dg-final { scan-tree-dump-times " \\+ " 0 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times " \\+ " 0 "optimized" { xfail *-*-* } }
> } */
> /* { dg-final { scan-tree-dump-times " \\* " 1 "optimized" } } */
>
> /* The if from the loop header copying remains in the code. */
