On Wed, Jul 17, 2024 at 1:29 PM Eikansh Gupta <[email protected]> wrote:
>
> Min and max could be optimized if both operands are defined by
> (same) variable restricted by an and(&). For signed types,
> optimization can be done when both constant have same sign bit.
> The patch also adds optimization for specific case of min/max(a, a&1).
>
> This patch adds match pattern for:
>
> max (a & CST0, a & CST1) -> a & CST0 IFF CST0 & CST1 == CST1
> min (a & CST0, a & CST1) -> a & CST0 IFF CST0 & CST1 == CST0
> min (a, a & 1) --> a & 1
> max (a, a & 1) --> a
>
> PR tree-optimization/109878
>
> gcc/ChangeLog:
>
> * match.pd min/max (a & CST0, a & CST1): New pattern.
> min/max (a, a & 1): New pattern.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/pr109878.c: New test.
> * gcc.dg/tree-ssa/pr109878-1.c: New test.
> * gcc.dg/tree-ssa/pr109878-2.c: New test.
> * gcc.dg/tree-ssa/pr109878-3.c: New test.
>
> Signed-off-by: Eikansh Gupta <[email protected]>
> ---
> gcc/match.pd | 22 ++++++++
> gcc/testsuite/gcc.dg/tree-ssa/pr109878-1.c | 64 ++++++++++++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/pr109878-2.c | 31 +++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/pr109878-3.c | 26 +++++++++
> gcc/testsuite/gcc.dg/tree-ssa/pr109878.c | 64 ++++++++++++++++++++++
> 5 files changed, 207 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr109878-1.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr109878-2.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr109878-3.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr109878.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 24a0bbead3e..029ec0b487f 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -4310,6 +4310,28 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> @0
> @2)))
>
> +/* min (a & CST0, a & CST1) -> a & CST0 IFF CST0 & CST1 == CST0 */
> +/* max (a & CST0, a & CST1) -> a & CST0 IFF CST0 & CST1 == CST1 */
> +/* If signed a, then both the constants should have same sign. */
> +(for minmax (min max)
> + (simplify
> + (minmax:c (bit_and@3 @0 INTEGER_CST@1) (bit_and@4 @0 INTEGER_CST@2))
The :c on minmax looks unnecessary
OK with removing that.
Richard.
> + (if (TYPE_UNSIGNED (type)
> + || ((tree_int_cst_sgn (@1) <= 0) == (tree_int_cst_sgn (@2) <= 0)))
> + (if ((wi::to_wide (@1) & wi::to_wide (@2))
> + == ((minmax == MIN_EXPR) ? wi::to_wide (@1) : wi::to_wide (@2)))
> + @3))))
> +
> +/* min (a, a & 1) --> a & 1 */
> +/* max (a, a & 1) --> a */
> +(for minmax (min max)
> + (simplify
> + (minmax:c @0 (bit_and@1 @0 integer_onep))
> + (if (TYPE_UNSIGNED(type))
> + (if (minmax == MIN_EXPR)
> + @1
> + @0))))
> +
> /* Simplify min (&var[off0], &var[off1]) etc. depending on whether
> the addresses are known to be less, equal or greater. */
> (for minmax (min max)
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr109878-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr109878-1.c
> new file mode 100644
> index 00000000000..509e59adea1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr109878-1.c
> @@ -0,0 +1,64 @@
> +/* PR tree-optimization/109878 */
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-optimized" } */
> +
> +/* All the constant pair <cst0, cst1> used here satisfy the condition:
> + (cst0 & cst1 == cst0) || (cst0 & cst1 == cst1).
> + If the above condition is true, then MIN_EXPR is not needed. */
> +int min_and(int a, int b) {
> + b = a & 3;
> + a = a & 1;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +int min_and1(int a, int b) {
> + b = a & 3;
> + a = a & 15;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +int min_and2(int a, int b) {
> + b = a & -7;
> + a = a & -3;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +int min_and3(int a, int b) {
> + b = a & -5;
> + a = a & -13;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* When constants are of opposite signs, the simplification will only
> + work for unsigned types. */
> +unsigned int min_and4(unsigned int a, unsigned int b) {
> + b = a & 3;
> + a = a & -5;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +unsigned int min_and5(unsigned int a, unsigned int b) {
> + b = a & -3;
> + a = a & 5;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " MIN_EXPR " "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr109878-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr109878-2.c
> new file mode 100644
> index 00000000000..62846d5d784
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr109878-2.c
> @@ -0,0 +1,31 @@
> +/* PR tree-optimization/109878 */
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-optimized" } */
> +
> +/* The testcases here should not get optimized with the patch.
> + For constant pair <cst0, cst1> the condition:
> + (cst0 & cst1 == cst0) || (cst0 & cst1 == cst1)
> + is false for the constants used here. */
> +int max_and(int a, int b) {
> +
> + b = a & 3;
> + a = a & 5;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* The constants in this function satisfy the condition but a is signed.
> + For signed types both the constants should have same sign. */
> +int min_and(int a, int b) {
> + b = a & 1;
> + a = a & -3;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* { dg-final { scan-tree-dump " MIN_EXPR " "optimized" } } */
> +/* { dg-final { scan-tree-dump " MAX_EXPR " "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr109878-3.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr109878-3.c
> new file mode 100644
> index 00000000000..c0b79ae4096
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr109878-3.c
> @@ -0,0 +1,26 @@
> +/* PR tree-optimization/109878 */
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-optimized" } */
> +
> +/* For unsigned types, min(a, a&1) should be simplified to a&1 and
> + should not generate MIN_EXPR. */
> +unsigned int min_1(unsigned int a, unsigned int b) {
> + b = a & 1;
> + if (b < a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* For unsigned types, max(a, a&1) should be simplified to a and
> + should not generate MAX_EXPR. */
> +unsigned int max_1(unsigned int a, unsigned int b) {
> + b = a & 1;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " MIN_EXPR " "optimized" } } */
> +/* { dg-final { scan-tree-dump-not " MAX_EXPR " "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr109878.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr109878.c
> new file mode 100644
> index 00000000000..6f13bafcf14
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr109878.c
> @@ -0,0 +1,64 @@
> +/* PR tree-optimization/109878 */
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fdump-tree-optimized" } */
> +
> +/* All the constant pair <cst0, cst1> used here satisfy the condition:
> + (cst0 & cst1 == cst0) || (cst0 & cst1 == cst1).
> + If the above condition is true, then MAX_EXPR is not needed. */
> +int max_and(int a, int b) {
> + b = a & 3;
> + a = a & 1;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +int max_and1(int a, int b) {
> + b = a & 3;
> + a = a & 15;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +int max_and2(int a, int b) {
> + b = a & -7;
> + a = a & -3;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +int max_and3(int a, int b) {
> + b = a & -5;
> + a = a & -13;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* When constants are of opposite signs, the simplification will only
> + work for unsigned types. */
> +unsigned int max_and4(unsigned int a, unsigned int b) {
> + b = a & 3;
> + a = a & -5;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +unsigned int max_and5(unsigned int a, unsigned int b) {
> + b = a & -3;
> + a = a & 5;
> + if (b > a)
> + return b;
> + else
> + return a;
> +}
> +
> +/* { dg-final { scan-tree-dump-not " MAX_EXPR " "optimized" } } */
> --
> 2.17.1
>
