On Tue, Sep 12, 2023 at 11:45 PM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Tue, Sep 12, 2023 at 5:31 PM Andrew Pinski via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > This adds a few more minmax cmp operand simplifications which were missed
> > before.
> > `MIN(a,b) < a` -> `a > b`
> > `MIN(a,b) >= a` -> `a <= b`
> > `MAX(a,b) > a` -> `a < b`
> > `MAX(a,b) <= a` -> `a >= b`
> >
> > OK? Bootstrapped and tested on x86_64-linux-gnu.
>
> OK. I wonder if any of these are also valid for FP types?
I was thinking about that too. I will look into that later this week.
Thanks,
Andrew
>
> > Note gcc.dg/pr96708-negative.c needed to updated to remove the
> > check for MIN/MAX as they have been optimized (correctly) away.
> >
> > PR tree-optimization/111364
> >
> > gcc/ChangeLog:
> >
> > * match.pd (`MIN (X, Y) == X`): Extend
> > to min/lt, min/ge, max/gt, max/le.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.c-torture/execute/minmaxcmp-1.c: New test.
> > * gcc.dg/tree-ssa/minmaxcmp-2.c: New test.
> > * gcc.dg/pr96708-negative.c: Update testcase.
> > * gcc.dg/pr96708-positive.c: Add comment about `return 0`.
> > ---
> > gcc/match.pd | 8 +--
> > .../gcc.c-torture/execute/minmaxcmp-1.c | 51 +++++++++++++++++++
> > gcc/testsuite/gcc.dg/pr96708-negative.c | 4 +-
> > gcc/testsuite/gcc.dg/pr96708-positive.c | 1 +
> > gcc/testsuite/gcc.dg/tree-ssa/minmaxcmp-2.c | 30 +++++++++++
> > 5 files changed, 89 insertions(+), 5 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.c-torture/execute/minmaxcmp-1.c
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/minmaxcmp-2.c
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 51985c1bad4..36e3da4841b 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -3902,9 +3902,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> > (maxmin @0 (bit_not @1))))
> >
> > /* MIN (X, Y) == X -> X <= Y */
> > -(for minmax (min min max max)
> > - cmp (eq ne eq ne )
> > - out (le gt ge lt )
> > +/* MIN (X, Y) < X -> X > Y */
> > +/* MIN (X, Y) >= X -> X <= Y */
> > +(for minmax (min min min min max max max max)
> > + cmp (eq ne lt ge eq ne gt le )
> > + out (le gt gt le ge lt lt ge )
> > (simplify
> > (cmp:c (minmax:c @0 @1) @0)
> > (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0)))
> > diff --git a/gcc/testsuite/gcc.c-torture/execute/minmaxcmp-1.c
> > b/gcc/testsuite/gcc.c-torture/execute/minmaxcmp-1.c
> > new file mode 100644
> > index 00000000000..6705a053768
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.c-torture/execute/minmaxcmp-1.c
> > @@ -0,0 +1,51 @@
> > +#define func(vol, op1, op2) \
> > +_Bool op1##_##op2##_##vol (int a, int b) \
> > +{ \
> > + vol int x = op_##op1(a, b); \
> > + return op_##op2(x, a); \
> > +}
> > +
> > +#define op_lt(a, b) ((a) < (b))
> > +#define op_le(a, b) ((a) <= (b))
> > +#define op_eq(a, b) ((a) == (b))
> > +#define op_ne(a, b) ((a) != (b))
> > +#define op_gt(a, b) ((a) > (b))
> > +#define op_ge(a, b) ((a) >= (b))
> > +#define op_min(a, b) ((a) < (b) ? (a) : (b))
> > +#define op_max(a, b) ((a) > (b) ? (a) : (b))
> > +
> > +
> > +#define funcs(a) \
> > + a(min,lt) \
> > + a(max,lt) \
> > + a(min,gt) \
> > + a(max,gt) \
> > + a(min,le) \
> > + a(max,le) \
> > + a(min,ge) \
> > + a(max,ge) \
> > + a(min,ne) \
> > + a(max,ne) \
> > + a(min,eq) \
> > + a(max,eq)
> > +
> > +#define funcs1(a,b) \
> > +func(,a,b) \
> > +func(volatile,a,b)
> > +
> > +funcs(funcs1)
> > +
> > +#define test(op1,op2) \
> > +do { \
> > + if (op1##_##op2##_(x,y) != op1##_##op2##_volatile(x,y)) \
> > + __builtin_abort(); \
> > +} while(0);
> > +
> > +int main()
> > +{
> > + for(int x = -10; x < 10; x++)
> > + for(int y = -10; y < 10; y++)
> > + {
> > + funcs(test)
> > + }
> > +}
> > diff --git a/gcc/testsuite/gcc.dg/pr96708-negative.c
> > b/gcc/testsuite/gcc.dg/pr96708-negative.c
> > index 91964d3b971..c9c1aa85558 100644
> > --- a/gcc/testsuite/gcc.dg/pr96708-negative.c
> > +++ b/gcc/testsuite/gcc.dg/pr96708-negative.c
> > @@ -42,7 +42,7 @@ int main()
> > return 0;
> > }
> >
> > -/* { dg-final { scan-tree-dump-times "MAX_EXPR" 2 "optimized" } } */
> > -/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "optimized" } } */
> > +/* Even though test[1-4] originally has MIN/MAX, those can be optimized
> > away
> > + into just comparing a and b arguments. */
> > /* { dg-final { scan-tree-dump-times "return 0;" 1 "optimized" } } */
> > /* { dg-final { scan-tree-dump-not { "return 1;" } "optimized" } } */
> > diff --git a/gcc/testsuite/gcc.dg/pr96708-positive.c
> > b/gcc/testsuite/gcc.dg/pr96708-positive.c
> > index 65af85344b6..12c5fedfd30 100644
> > --- a/gcc/testsuite/gcc.dg/pr96708-positive.c
> > +++ b/gcc/testsuite/gcc.dg/pr96708-positive.c
> > @@ -42,6 +42,7 @@ int main()
> > return 0;
> > }
> >
> > +/* Note main has one `return 0`. */
> > /* { dg-final { scan-tree-dump-times "return 0;" 3 "optimized" } } */
> > /* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */
> > /* { dg-final { scan-tree-dump-not { "MAX_EXPR" } "optimized" } } */
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmaxcmp-2.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/minmaxcmp-2.c
> > new file mode 100644
> > index 00000000000..f64a9253cfb
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmaxcmp-2.c
> > @@ -0,0 +1,30 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O2 -fdump-tree-original" } */
> > +/* PR tree-optimization/111364 */
> > +
> > +#define min1(a, b) ((a) < (b) ? (a) : (b))
> > +#define max1(a, b) ((a) > (b) ? (a) : (b))
> > +
> > +int minlt(int a, int b)
> > +{
> > + return min1(a, b) < a; // b < a or a > b
> > +}
> > +/* { dg-final { scan-tree-dump "return a > b;|return b < a;" "original" }
> > } */
> > +
> > +int minge(int c, int d)
> > +{
> > + return min1(c, d) >= c; // d >= c or c <= d
> > +}
> > +/* { dg-final { scan-tree-dump "return c <= d;|return d <= c;" "original"
> > } } */
> > +
> > +int maxgt(int e, int f)
> > +{
> > + return max1(e, f) > e; // e > f or f < e
> > +}
> > +/* { dg-final { scan-tree-dump "return e < f;|return f > e;" "original" }
> > } */
> > +
> > +int maxle(int x, int y)
> > +{
> > + return max1(x, y) <= x; // y <= x or x >= y
> > +}
> > +/* { dg-final { scan-tree-dump "return x >= y;|return y <= x;" "original"
> > } } */
> > --
> > 2.31.1
> >
