On May 4, 2017 5:09:15 PM GMT+02:00, Martin Jambor <mjam...@suse.cz> wrote:
>Hi,
>
>PR 80622 happens because when setting grp_write lazily, the code does
>not acknowledge that constant pool bases come initialized and so
>contain data even when not written to. The patch below fixes that but
>it also puts a test for pre-initialization into a special function,
>uses it at all appropriate places and moves the test in question to an
>earlier time, which is a tiny bit cheaper because it may avoid
>unnecessary re-invocation of propagate_subaccesses_across_link.
>
>Bootstrapped and tested on x86_64-linux, OK for trunk?
OK.
Richard.
>Thanks,
>
>Martin
>
>
>
>2017-05-04 Martin Jambor <mjam...@suse.cz>
>
> PR tree-optimization/80622
> * tree-sra.c (comes_initialized_p): New function.
> (build_accesses_from_assign): Only set write lazily when
> comes_initialized_p is false.
> (analyze_access_subtree): Use comes_initialized_p.
> (propagate_subaccesses_across_link): Assert !comes_initialized_p
> instead of testing for PARM_DECL.
>
>testsuite/
> * gcc.dg/tree-ssa/pr80622.c: New test.
>---
> gcc/testsuite/gcc.dg/tree-ssa/pr80622.c | 19 +++++++++++++++++++
>gcc/tree-sra.c | 29
>+++++++++++++++++++++--------
> 2 files changed, 40 insertions(+), 8 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr80622.c
>
>diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr80622.c
>b/gcc/testsuite/gcc.dg/tree-ssa/pr80622.c
>new file mode 100644
>index 00000000000..96dcb8fcdc0
>--- /dev/null
>+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr80622.c
>@@ -0,0 +1,19 @@
>+/* { dg-do run } */
>+/* { dg-options "-O" } */
>+
>+struct S { int d; char e; int f; char g; } a;
>+char c;
>+
>+int
>+main ()
>+{
>+ struct S b[][1] = {3, 0, 3, 4, 3, 0, 3, 4, 3, 0, 3, 4, 3, 0, 3, 4,
>3,
>+ 0, 3, 4, 3, 0, 3, 4, 3, 0, 3, 4, 3, 0, 3, 4, 3,
>0,
>+ 3, 4, 3, 4, 7, 7, 3, 5, 0, 3, 4, 7, 7, 3, 5, 0,
>3,
>+ 4, 3, 4, 7, 7, 3, 5, 0, 3, 4, 7, 7, 3, 5, 0, 3,
>4};
>+ a = b[4][0];
>+ c = b[4][0].e;
>+ if (a.g != 4)
>+ __builtin_abort ();
>+ return 0;
>+}
>diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
>index 1606573aead..8ac9c0783ff 100644
>--- a/gcc/tree-sra.c
>+++ b/gcc/tree-sra.c
>@@ -1305,6 +1305,15 @@ disqualify_if_bad_bb_terminating_stmt (gimple
>*stmt, tree lhs, tree rhs)
> return false;
> }
>
>+/* Return true if the nature of BASE is such that it contains data
>even if
>+ there is no write to it in the function. */
>+
>+static bool
>+comes_initialized_p (tree base)
>+{
>+ return TREE_CODE (base) == PARM_DECL || constant_decl_p (base);
>+}
>+
>/* Scan expressions occurring in STMT, create access structures for all
>accesses
>to candidates for scalarization and remove those candidates which occur
>in
>statements or expressions that prevent them from being split apart.
>Return
>@@ -1364,8 +1373,10 @@ build_accesses_from_assign (gimple *stmt)
> link->racc = racc;
> add_link_to_rhs (racc, link);
>/* Let's delay marking the areas as written until propagation of
>accesses
>- across link. */
>- lacc->write = false;
>+ across link, unless the nature of rhs tells us that its data comes
>+ from elsewhere. */
>+ if (!comes_initialized_p (racc->base))
>+ lacc->write = false;
> }
>
> return lacc || racc;
>@@ -2472,8 +2483,7 @@ analyze_access_subtree (struct access *root,
>struct access *parent,
>
> if (!hole || root->grp_total_scalarization)
> root->grp_covered = 1;
>- else if (root->grp_write || TREE_CODE (root->base) == PARM_DECL
>- || constant_decl_p (root->base))
>+ else if (root->grp_write || comes_initialized_p (root->base))
> root->grp_unscalarized_data = 1; /* not covered and written to */
> return sth_created;
> }
>@@ -2581,11 +2591,14 @@ propagate_subaccesses_across_link (struct
>access *lacc, struct access *racc)
>
>/* IF the LHS is still not marked as being written to, we only need to
>do so
> if the RHS at this level actually was. */
>- if (!lacc->grp_write &&
>- (racc->grp_write || TREE_CODE (racc->base) == PARM_DECL))
>+ if (!lacc->grp_write)
> {
>- lacc->grp_write = true;
>- ret = true;
>+ gcc_checking_assert (!comes_initialized_p (racc->base));
>+ if (racc->grp_write)
>+ {
>+ lacc->grp_write = true;
>+ ret = true;
>+ }
> }
>
> if (is_gimple_reg_type (lacc->type)
