On Thu, 17 Sep 2020, Michael Matz wrote:
> Hello,
>
> On Wed, 16 Sep 2020, Richard Biener wrote:
>
> > This removes the canonicalization of X + -CST to X - CST to facilitate
> > SLP vectorization analysis where we currently treat the added testcase
> > as two-operation plus blend vectorization opportunity. While there
> > may be the possibility to avoid this in the vectorizer itself the
> > canonicalization is somewhat premature - it's motivation is that
> > a FP constant of both signs is common and thus canonicalizing to
> > positive values optimizes constant pool. But if you mix, say,
> > x * -7.1 and x - 7.1 this backfires - this instead looks like
> > a local optimization to be applied in RTL CSE or even LRA
> > load inheritance. I filed PR97071 for this.
> >
> > Bootstrapped and tested on x86_64-unknown-linux-gnu, any objections?
>
> You need to adjust the comments, this will be very confusing in a couple
> years:
>
> /* We want to canonicalize to positive real constants. Pretend
> that only negative ones can be easily negated. */
> return true;
Yep, fixed. I've spotted and changed the above only after testing
and re-testing revealed
FAIL: gcc.dg/extract_recip_4.c scan-tree-dump-times optimized
"mult_expr" 7
FAIL: gcc.dg/extract_recip_4.c scan-tree-dump-times optimized
"rdiv_expr" 3
FAIL: gcc.dg/pr19988.c scan-tree-dump-times optimized " \\\\* " 2
FAIL: gcc.dg/pr19988.c scan-tree-dump-times original " 1.23" 2
where FAIL: gcc.dg/pr19988.c is now fixed with the FRE patch pushed
today. FAIL: gcc.dg/extract_recip_4.c looks quite special (the
different canonicalization makes hoisting a division no longer
happen which in turn alters the recip pass cost consideration),
a slightly altered testcase would already FAIL.
Still I've not pushed this for now, I'll eventually come back though.
Richard.
>
> Ciao,
> Michael.
>
>
> >
> > Thanks,
> > Richard.
> >
> > 2020-09-16 Richard Biener <rguent...@suse.de>
> >
> > * fold-const.c (fold_binary_loc): Remove condition
> > on REAL_CST for A - B -> A + (-B) transform.
> > (negate_expr_p): Remove condition on REAL_CST.
> > * match.pd (negate_expr_p): Likewise.
> > (X + -C -> X - C): Remove.
> >
> > * gcc.dg/vect/slp-49.c: New testcase.
> > * gcc.dg/tree-ssa/pr90356-1.c: Adjust.
> > * gcc.dg/tree-ssa/pr90356-3.c: Likewise.
> > * gcc.dg/tree-ssa/pr90356-4.c: Likewise.
> > * gcc.target/i386/pr54855-3.c: Likewise.
> > * gfortran.dg/reassoc_1.f90: Likewise.
> > * gfortran.dg/reassoc_2.f90: Likewise.
> > ---
> > gcc/fold-const.c | 7 ++-----
> > gcc/match.pd | 11 +----------
> > gcc/testsuite/gcc.dg/tree-ssa/pr90356-1.c | 4 ++--
> > gcc/testsuite/gcc.dg/tree-ssa/pr90356-3.c | 2 +-
> > gcc/testsuite/gcc.dg/tree-ssa/pr90356-4.c | 2 +-
> > gcc/testsuite/gcc.dg/vect/slp-49.c | 15 +++++++++++++++
> > gcc/testsuite/gcc.target/i386/pr54855-3.c | 2 +-
> > gcc/testsuite/gfortran.dg/reassoc_1.f90 | 2 +-
> > gcc/testsuite/gfortran.dg/reassoc_2.f90 | 2 +-
> > 9 files changed, 25 insertions(+), 22 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.dg/vect/slp-49.c
> >
> > diff --git a/gcc/fold-const.c b/gcc/fold-const.c
> > index 0cc80adf632..ec369169a4c 100644
> > --- a/gcc/fold-const.c
> > +++ b/gcc/fold-const.c
> > @@ -401,7 +401,7 @@ negate_expr_p (tree t)
> > case REAL_CST:
> > /* We want to canonicalize to positive real constants. Pretend
> > that only negative ones can be easily negated. */
> > - return REAL_VALUE_NEGATIVE (TREE_REAL_CST (t));
> > + return true;
> >
> > case COMPLEX_CST:
> > return negate_expr_p (TREE_REALPART (t))
> > @@ -10962,10 +10962,7 @@ fold_binary_loc (location_t loc, enum tree_code
> > code, tree type,
> > /* A - B -> A + (-B) if B is easily negatable. */
> > if (negate_expr_p (op1)
> > && ! TYPE_OVERFLOW_SANITIZED (type)
> > - && ((FLOAT_TYPE_P (type)
> > - /* Avoid this transformation if B is a positive REAL_CST.
> > */
> > - && (TREE_CODE (op1) != REAL_CST
> > - || REAL_VALUE_NEGATIVE (TREE_REAL_CST (op1))))
> > + && (FLOAT_TYPE_P (type)
> > || INTEGRAL_TYPE_P (type)))
> > return fold_build2_loc (loc, PLUS_EXPR, type,
> > fold_convert_loc (loc, type, arg0),
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 7d63bb973cb..9f14d50ae2d 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -1307,8 +1307,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> > (negate @0)
> > (if (!TYPE_OVERFLOW_SANITIZED (type))))
> > (match negate_expr_p
> > - REAL_CST
> > - (if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (t)))))
> > + REAL_CST)
> > /* VECTOR_CST handling of non-wrapping types would recurse in unsupported
> > ways. */
> > (match negate_expr_p
> > @@ -3326,14 +3325,6 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >
> > /* Canonicalization of binary operations. */
> >
> > -/* Convert X + -C into X - C. */
> > -(simplify
> > - (plus @0 REAL_CST@1)
> > - (if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (@1)))
> > - (with { tree tem = const_unop (NEGATE_EXPR, type, @1); }
> > - (if (!TREE_OVERFLOW (tem) || !flag_trapping_math)
> > - (minus @0 { tem; })))))
> > -
> > /* Convert x+x into x*2. */
> > (simplify
> > (plus @0 @0)
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr90356-1.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/pr90356-1.c
> > index c3a15ea21af..ac95ec56810 100644
> > --- a/gcc/testsuite/gcc.dg/tree-ssa/pr90356-1.c
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr90356-1.c
> > @@ -2,8 +2,8 @@
> > /* { dg-do compile } */
> > /* { dg-options "-O2 -fno-rounding-math -fsignaling-nans -fsigned-zeros
> > -fdump-tree-optimized" } */
> > /* { dg-final { scan-tree-dump-times "x_\[0-9]*.D. \\+ 0.0;" 12
> > "optimized" } } */
> > -/* { dg-final { scan-tree-dump-times "y_\[0-9]*.D. - 0.0;" 4 "optimized" }
> > } */
> > -/* { dg-final { scan-tree-dump-times " \[+-] 0.0;" 16 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times "y_\[0-9]*.D. \\+ -0.0;" 4
> > "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times " \\+ -?0.0;" 16 "optimized" } } */
> >
> > double f1 (double x) { return (x + 0.0) + 0.0; }
> > double f2 (double y) { return (y + (-0.0)) + (-0.0); }
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr90356-3.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/pr90356-3.c
> > index e658130c69f..951971b95ee 100644
> > --- a/gcc/testsuite/gcc.dg/tree-ssa/pr90356-3.c
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr90356-3.c
> > @@ -1,6 +1,6 @@
> > /* PR tree-optimization/90356 */
> > /* { dg-do compile } */
> > /* { dg-options "-O2 -frounding-math -fsignaling-nans -fsigned-zeros
> > -fdump-tree-optimized" } */
> > -/* { dg-final { scan-tree-dump-times " \[+-] 0.0;" 32 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times " \\+ -?0.0;" 32 "optimized" } } */
> >
> > #include "pr90356-1.c"
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr90356-4.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/pr90356-4.c
> > index 126cd10928b..3459ddba356 100644
> > --- a/gcc/testsuite/gcc.dg/tree-ssa/pr90356-4.c
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr90356-4.c
> > @@ -1,6 +1,6 @@
> > /* PR tree-optimization/90356 */
> > /* { dg-do compile } */
> > /* { dg-options "-O2 -frounding-math -fno-signaling-nans -fsigned-zeros
> > -fdump-tree-optimized" } */
> > -/* { dg-final { scan-tree-dump-times " \[+-] 0.0;" 32 "optimized" } } */
> > +/* { dg-final { scan-tree-dump-times " \\+ -?0.0;" 32 "optimized" } } */
> >
> > #include "pr90356-1.c"
> > diff --git a/gcc/testsuite/gcc.dg/vect/slp-49.c
> > b/gcc/testsuite/gcc.dg/vect/slp-49.c
> > new file mode 100644
> > index 00000000000..4b3ec77b99d
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/vect/slp-49.c
> > @@ -0,0 +1,15 @@
> > +/* { dg-do compile } */
> > +/* { dg-require-effective-target vect_double } */
> > +
> > +void foo (double *x)
> > +{
> > + for (int i = 0; i < 1024; ++i)
> > + {
> > + x[2*i] += 1.0;
> > + x[2*i+1] -= 2.0;
> > + }
> > +}
> > +
> > +/* { dg-final { scan-tree-dump "loop vectorized" "vect" } } */
> > +/* The loop should be SLPed with uniform plus. */
> > +/* { dg-final { scan-tree-dump-not "VEC_PERM" "vect" } } */
> > diff --git a/gcc/testsuite/gcc.target/i386/pr54855-3.c
> > b/gcc/testsuite/gcc.target/i386/pr54855-3.c
> > index 3c15dfc93d1..802d6882e43 100644
> > --- a/gcc/testsuite/gcc.target/i386/pr54855-3.c
> > +++ b/gcc/testsuite/gcc.target/i386/pr54855-3.c
> > @@ -1,6 +1,6 @@
> > /* { dg-do compile } */
> > /* { dg-options "-O2 -msse2 -mfpmath=sse" } */
> > -/* { dg-final { scan-assembler-times "subsd" 1 } } */
> > +/* { dg-final { scan-assembler-times "addsd" 1 } } */
> > /* { dg-final { scan-assembler-not "movapd" } } */
> > /* { dg-final { scan-assembler-not "movsd" } } */
> >
> > diff --git a/gcc/testsuite/gfortran.dg/reassoc_1.f90
> > b/gcc/testsuite/gfortran.dg/reassoc_1.f90
> > index e3d84c4ffd9..19b47fc7ce6 100644
> > --- a/gcc/testsuite/gfortran.dg/reassoc_1.f90
> > +++ b/gcc/testsuite/gfortran.dg/reassoc_1.f90
> > @@ -9,4 +9,4 @@ end
> >
> > ! We need an explicit +5 and -5, and an intermediate ((bla)) expression
> > ! (the reassoc barrier). Make use of "." matching lineends.
> > -! { dg-final { scan-tree-dump "\\\+ 5.*\\\)\\\).* - 5" "optimized" } }
> > +! { dg-final { scan-tree-dump "\\\+ 5.*\\\)\\\).* \\\+ -5" "optimized" } }
> > diff --git a/gcc/testsuite/gfortran.dg/reassoc_2.f90
> > b/gcc/testsuite/gfortran.dg/reassoc_2.f90
> > index 3e323eb0134..62361619932 100644
> > --- a/gcc/testsuite/gfortran.dg/reassoc_2.f90
> > +++ b/gcc/testsuite/gfortran.dg/reassoc_2.f90
> > @@ -12,4 +12,4 @@ function test(a)
> > test = d
> > end
> >
> > -! { dg-final { scan-tree-dump "- 5" "optimized" } }
> > +! { dg-final { scan-tree-dump "\\\+ -5" "optimized" } }
> >
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imend
