| Message ID | afc099f1-ed03-c91a-c9bb-506f0784a4f3@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] Skip constant folding for fmin/max when either argument is sNaN [PR105414] | expand |
On Tue, May 10, 2022 at 10:10 AM HAO CHEN GUI <guihaoc@linux.ibm.com> wrote: > > Hi, > This patch skips constant folding for fmin/max when either argument > is sNaN. According to C standard, > fmin(sNaN, sNaN）= qNaN, fmin(sNaN, NaN) = qNaN > So signaling NaN should be tested and skipped for fmin/max in match.pd. > > The V2 patch splits the for loop and keeps MIN/MAX_EXPR unchanged. > > Bootstrapped and tested on ppc64 Linux BE and LE with no regressions. > Is this okay for trunk? Any recommendations? Thanks a lot. OK. Richard. > ChangeLog > 2022-05-10 Haochen Gui <guihaoc@linux.ibm.com> > > gcc/ > PR target/105414 > * match.pd (minmax): Skip constant folding for fmin/fmax when both > arguments are sNaN or one is sNaN and another is NaN. > > gcc/testsuite/ > PR target/105414 > * gcc.dg/pr105414.c: New. > > > patch.diff > diff --git a/gcc/match.pd b/gcc/match.pd > index 6d691d302b3..6fb8806412a 100644 > --- a/gcc/match.pd > +++ b/gcc/match.pd > @@ -3095,10 +3095,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > > /* Simplifications of MIN_EXPR, MAX_EXPR, fmin() and fmax(). */ > > -(for minmax (min max FMIN_ALL FMAX_ALL) > +(for minmax (min max) > (simplify > (minmax @0 @0) > @0)) > +/* For fmin() and fmax(), skip folding when both are sNaN. */ > +(for minmax (FMIN_ALL FMAX_ALL) > + (simplify > + (minmax @0 @0) > + (if (!tree_expr_maybe_signaling_nan_p (@0)) > + @0))) > /* min(max(x,y),y) -> y. */ > (simplify > (min:c (max:c @0 @1) @1) > @@ -3198,12 +3204,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) > (minmax @1 (convert @2))))) > > (for minmax (FMIN_ALL FMAX_ALL) > - /* If either argument is NaN, return the other one. Avoid the > - transformation if we get (and honor) a signalling NaN. */ > + /* If either argument is NaN and other one is not sNaN, return the other > + one. Avoid the transformation if we get (and honor) a signalling NaN. */ > (simplify > (minmax:c @0 REAL_CST@1) > - (if (real_isnan (TREE_REAL_CST_PTR (@1)) > - && (!HONOR_SNANS (@1) || !TREE_REAL_CST (@1).signalling)) > + (if (real_isnan (TREE_REAL_CST_PTR (@1)) > + && (!HONOR_SNANS (@1) || !TREE_REAL_CST (@1).signalling) > + && !tree_expr_maybe_signaling_nan_p (@0)) > @0))) > /* Convert fmin/fmax to MIN_EXPR/MAX_EXPR. C99 requires these > functions to return the numeric arg if the other one is NaN. > diff --git a/gcc/testsuite/gcc.dg/pr105414.c b/gcc/testsuite/gcc.dg/pr105414.c > new file mode 100644 > index 00000000000..78772700acf > --- /dev/null > +++ b/gcc/testsuite/gcc.dg/pr105414.c > @@ -0,0 +1,30 @@ > +/* { dg-do run { target { *-*-linux* *-*-gnu* } } } */ > +/* { dg-options "-O1 -fsignaling-nans -lm" } */ > +/* { dg-add-options ieee } */ > +/* { dg-require-effective-target issignaling } */ > + > + > +#define _GNU_SOURCE > +#include <stdio.h> > +#include <math.h> > + > +int main() > +{ > + double a = __builtin_nans (""); > + > + if (issignaling (fmin (a, a))) > + __builtin_abort (); > + > + if (issignaling (fmax (a, a))) > + __builtin_abort (); > + > + double b = __builtin_nan (""); > + > + if (issignaling (fmin (a, b))) > + __builtin_abort (); > + > + if (issignaling (fmax (a, b))) > + __builtin_abort (); > + > + return 0; > +}
diff --git a/gcc/match.pd b/gcc/match.pd index 6d691d302b3..6fb8806412a 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -3095,10 +3095,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) /* Simplifications of MIN_EXPR, MAX_EXPR, fmin() and fmax(). */ -(for minmax (min max FMIN_ALL FMAX_ALL) +(for minmax (min max) (simplify (minmax @0 @0) @0)) +/* For fmin() and fmax(), skip folding when both are sNaN. */ +(for minmax (FMIN_ALL FMAX_ALL) + (simplify + (minmax @0 @0) + (if (!tree_expr_maybe_signaling_nan_p (@0)) + @0))) /* min(max(x,y),y) -> y. */ (simplify (min:c (max:c @0 @1) @1) @@ -3198,12 +3204,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (minmax @1 (convert @2))))) (for minmax (FMIN_ALL FMAX_ALL) - /* If either argument is NaN, return the other one. Avoid the - transformation if we get (and honor) a signalling NaN. */ + /* If either argument is NaN and other one is not sNaN, return the other + one. Avoid the transformation if we get (and honor) a signalling NaN. */ (simplify (minmax:c @0 REAL_CST@1) - (if (real_isnan (TREE_REAL_CST_PTR (@1)) - && (!HONOR_SNANS (@1) || !TREE_REAL_CST (@1).signalling)) + (if (real_isnan (TREE_REAL_CST_PTR (@1)) + && (!HONOR_SNANS (@1) || !TREE_REAL_CST (@1).signalling) + && !tree_expr_maybe_signaling_nan_p (@0)) @0))) /* Convert fmin/fmax to MIN_EXPR/MAX_EXPR. C99 requires these functions to return the numeric arg if the other one is NaN. diff --git a/gcc/testsuite/gcc.dg/pr105414.c b/gcc/testsuite/gcc.dg/pr105414.c new file mode 100644 index 00000000000..78772700acf --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr105414.c @@ -0,0 +1,30 @@ +/* { dg-do run { target { *-*-linux* *-*-gnu* } } } */ +/* { dg-options "-O1 -fsignaling-nans -lm" } */ +/* { dg-add-options ieee } */ +/* { dg-require-effective-target issignaling } */ + + +#define _GNU_SOURCE +#include <stdio.h> +#include <math.h> + +int main() +{ + double a = __builtin_nans (""); + + if (issignaling (fmin (a, a))) + __builtin_abort (); + + if (issignaling (fmax (a, a))) + __builtin_abort (); + + double b = __builtin_nan (""); + + if (issignaling (fmin (a, b))) + __builtin_abort (); + + if (issignaling (fmax (a, b))) + __builtin_abort (); + + return 0; +}