On Mon, Sep 6, 2021 at 7:31 AM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apin...@marvell.com>
>
> These two testcases have been failing since GCC 5 but things
> have improved such that adding a simplification to match.pd
> for this case is easier than before.
> In the end we have the following IR:
> ....
> _5 = &a[1] + _4;
> _7 = &a + _13;
> if (_5 != _7)
>
> So we can fold the _5 != _7 into:
> (&a[1] - &a) + _4 != _13
>
> The subtraction is folded into constant by ptr_difference_const.
> In this case, the full expression gets folded into a constant
> and we are able to remove the if statement.
>
> OK? Bootstrapped and tested on aarch64-linux-gnu with no regressions.
OK.
Thanks,
Richard.
> gcc/ChangeLog:
>
> * match.pd: Add simplification of pointer_diff of two pointer_plus
> with addr_expr in the first operand of each pointer_plus.
> Add simplificatoin of ne/eq of two pointer_plus with addr_expr
> in the first operand of each pointer_plus.
>
> gcc/testsuite/ChangeLog:
>
> * c-c++-common/pr19807-2.c: Enable for all targets and remove the
> xfail.
> * c-c++-common/pr19807-3.c: Likewise.
> ---
> gcc/match.pd | 15 +++++++++++++++
> gcc/testsuite/c-c++-common/pr19807-2.c | 5 ++---
> gcc/testsuite/c-c++-common/pr19807-3.c | 5 ++---
> 3 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index f920bc4b7c1..cc7809dfe0f 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -2063,6 +2063,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (if (ptr_difference_const (@0, @1, &diff))
> { build_int_cst_type (type, diff); }))))
>
> +/* (&a+b) - (&a[1] + c) -> sizeof(a[0]) + (b - c) */
> +(simplify
> + (pointer_diff (pointer_plus ADDR_EXPR@0 @1) (pointer_plus ADDR_EXPR@2 @3))
> + (with { poly_int64 diff; }
> + (if (ptr_difference_const (@0, @2, &diff))
> + (plus { build_int_cst_type (type, diff); } (convert (minus @1 @3))))))
> +
> +/* (&a+b) !=/== (&a[1] + c) -> sizeof(a[0]) + b !=/== c */
> +(for neeq (ne eq)
> + (simplify
> + (neeq (pointer_plus ADDR_EXPR@0 @1) (pointer_plus ADDR_EXPR@2 @3))
> + (with { poly_int64 diff; tree inner_type = TREE_TYPE (@1);}
> + (if (ptr_difference_const (@0, @2, &diff))
> + (neeq (plus { build_int_cst_type (inner_type, diff); } @1) @3)))))
> +
> /* Canonicalize (T *)(ptr - ptr-cst) to &MEM[ptr + -ptr-cst]. */
> (simplify
> (convert (pointer_diff @0 INTEGER_CST@1))
> diff --git a/gcc/testsuite/c-c++-common/pr19807-2.c
> b/gcc/testsuite/c-c++-common/pr19807-2.c
> index d2c010140d0..529b9c97322 100644
> --- a/gcc/testsuite/c-c++-common/pr19807-2.c
> +++ b/gcc/testsuite/c-c++-common/pr19807-2.c
> @@ -1,5 +1,4 @@
> -/* Some targets can optimize this on RTL. */
> -/* { dg-do link { target { x86_64-*-* i?86-*-* } } } */
> +/* { dg-do link } */
> /* { dg-options "-O -fdump-tree-optimized" } */
>
> extern void link_error(void);
> @@ -12,4 +11,4 @@ int main()
> return 0;
> }
>
> -/* { dg-final { scan-tree-dump-not "link_error" "optimized" { xfail *-*-* }
> } } */
> +/* { dg-final { scan-tree-dump-not "link_error" "optimized" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr19807-3.c
> b/gcc/testsuite/c-c++-common/pr19807-3.c
> index bb7f9827725..31c88f3b850 100644
> --- a/gcc/testsuite/c-c++-common/pr19807-3.c
> +++ b/gcc/testsuite/c-c++-common/pr19807-3.c
> @@ -1,5 +1,4 @@
> -/* Some targets can optimize this on RTL. */
> -/* { dg-do link { target { x86_64-*-* i?86-*-* } } } */
> +/* { dg-do link } */
> /* { dg-options "-O -fdump-tree-optimized" } */
>
> extern void link_error(void);
> @@ -12,4 +11,4 @@ int main()
> return 0;
> }
>
> -/* { dg-final { scan-tree-dump-not "link_error" "optimized" { xfail *-*-* }
> } } */
> +/* { dg-final { scan-tree-dump-not "link_error" "optimized" } } */
> --
> 2.17.1
>
