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?
> 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
>
