On Tue, Aug 9, 2016 at 4:04 PM, Patrick Palka <patr...@parcs.ath.cx> wrote:
> Hi, this patch makes match.pd to shorten comparisons that involve a
> sign-changing cast from a shorter unsigned type to a wider signed type.
> This should be safe to do because a wider signed type can hold all the
> possible values of a shorter unsigned type.
>
> This change causes vrp23.c and vrp24.c to fail because it makes the
> "n_sets > 0" tests within get trivially simplified by forwprop and so
> there is nothing left to simplify by VRP. Fixed by passing
> -fno-tree-forwprop in these tests.
>
> Bootstrapped + regtested on x86_64-pc-linux-gnu. Does this look OK to commit?
Ok.
Thanks,
Richard.
> gcc/ChangeLog:
>
> PR middle-end/71654
> * match.pd ((T)A CMP (T)B -> A CMP B): Allow (T)A to be a
> sign-changing cast from a shorter unsigned type to a wider
> signed type.
>
> gcc/testsuite/ChangeLog:
>
> PR middle-end/71654
> * gcc.dg/c-c++-common/pr71654.c: New test.
> * gcc.dg/tree-ssa/vrp23: Add -fno-tree-forwprop to
> dg-options.
> * gcc.dg/tree-ssa/vrp24: Likewise.
> ---
> gcc/match.pd | 4 +++-
> gcc/testsuite/c-c++-common/pr71654.c | 28 ++++++++++++++++++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/vrp23.c | 2 +-
> gcc/testsuite/gcc.dg/tree-ssa/vrp24.c | 2 +-
> 4 files changed, 33 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/c-c++-common/pr71654.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index ac7cfff..da87b02 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -2350,7 +2350,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (if (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (TREE_TYPE (@00)))
> /* If possible, express the comparison in the shorter mode. */
> (if ((cmp == EQ_EXPR || cmp == NE_EXPR
> - || TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (TREE_TYPE
> (@00)))
> + || TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (TREE_TYPE
> (@00))
> + || (!TYPE_UNSIGNED (TREE_TYPE (@0))
> + && TYPE_UNSIGNED (TREE_TYPE (@00))))
> && (types_match (TREE_TYPE (@10), TREE_TYPE (@00))
> || ((TYPE_PRECISION (TREE_TYPE (@00))
> >= TYPE_PRECISION (TREE_TYPE (@10)))
> diff --git a/gcc/testsuite/c-c++-common/pr71654.c
> b/gcc/testsuite/c-c++-common/pr71654.c
> new file mode 100644
> index 0000000..2942493
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr71654.c
> @@ -0,0 +1,28 @@
> +/* PR middle-end/71654 */
> +/* { dg-do link } */
> +/* { dg-options "-O2" } */
> +
> +unsigned char i0, i1;
> +
> +void foo (void);
> +
> +int
> +main (void)
> +{
> + int j = i0;
> + if (j < 4)
> + {
> + if (i0 & 4)
> + foo ();
> + }
> +
> + unsigned int k = i1;
> + if (k < 8)
> + {
> + if (i1 & 8)
> + foo ();
> + }
> +
> + return 0;
> +}
> +
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp23.c
> b/gcc/testsuite/gcc.dg/tree-ssa/vrp23.c
> index b877ccc..ae68c090 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/vrp23.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp23.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
> +/* { dg-options "-O2 -fno-tree-forwprop -fdump-tree-vrp1-details" } */
>
> void aa (void);
> void aos (void);
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp24.c
> b/gcc/testsuite/gcc.dg/tree-ssa/vrp24.c
> index e740575..853ee21 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/vrp24.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp24.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
> +/* { dg-options "-O2 -fno-tree-forwprop -fdump-tree-vrp1-details" } */
>
>
> struct rtx_def;
> --
> 2.9.2.614.g990027a
>
