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Re: [pr 69666] No SRA default_def replacements for unscalarizable
- From: Richard Biener <rguenther at suse dot de>
- To: Martin Jambor <mjambor at suse dot cz>,GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 19 Feb 2016 17:56:51 +0100
- Subject: Re: [pr 69666] No SRA default_def replacements for unscalarizable
- Authentication-results: sourceware.org; auth=none
- References: <20160219162156 dot GA16767 at virgil dot suse dot cz>
On February 19, 2016 5:21:56 PM GMT+01:00, Martin Jambor <mjambor@suse.cz> wrote:
>Hi,
>
>in PR 69666, SRA attempts to turn a load from an aggregate that is
>uninitialized into a load from a default definition SSA name (which
>something it does to generate an appropriate warning later) but
>unfortunately it does so using an access structure which is
>representable with __int128 when the load in question is smaller. It
>then attempts to fix it up only to create an invalid V_C_E. In this
>case, the correct thing to do is not to attempt the transformation,
>when there are smaller accesses, which can be figured out by looking
>at the unscalarizable_region flag of the access.
>
>Bootstrapped and tested on x86_64, OK for trunk and later for the 5
>branch?
OK.
Richard.
>Thanks,
>
>Martin
>
>
>2016-02-19 Martin Jambor <mjambor@suse.cz>
>
> PR tree-optimization/69666
> * tree-sra.c (sra_modify_assign): Do not attempt to create
> defaut_def replacements for unscalarizable regions.
>
>testsuite/
> * gcc.dg/tree-ssa/pr69666.c: New test.
>---
> gcc/testsuite/gcc.dg/tree-ssa/pr69666.c | 16 ++++++++++++++++
> gcc/tree-sra.c | 1 +
> 2 files changed, 17 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr69666.c
>
>diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr69666.c
>b/gcc/testsuite/gcc.dg/tree-ssa/pr69666.c
>new file mode 100644
>index 0000000..9be77ea
>--- /dev/null
>+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr69666.c
>@@ -0,0 +1,16 @@
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -w" } */
>+
>+int a, c, d;
>+float b;
>+void *memcpy();
>+int fun1(int p1, unsigned char *p2) {
>+ p2[p1] = b;
>+ return a;
>+}
>+void fun2() {
>+ unsigned char e[16];
>+ fun1(16, e);
>+ d = e[d];
>+ memcpy(&c, e, sizeof(e));
>+}
>diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
>index 72157ed..663ded2 100644
>--- a/gcc/tree-sra.c
>+++ b/gcc/tree-sra.c
>@@ -3339,6 +3339,7 @@ sra_modify_assign (gimple *stmt,
>gimple_stmt_iterator *gsi)
> }
> else if (racc
> && !racc->grp_unscalarized_data
>+ && !racc->grp_unscalarizable_region
> && TREE_CODE (lhs) == SSA_NAME
> && !access_has_replacements_p (racc))
> {