On Wed, Sep 23, 2020 at 10:44 AM Jan Hubicka <hubi...@ucw.cz> wrote:
>
> Hi,
> this is first of cleanup patches for mod-ref interfaces. It removes code
> duplication between ipa-pure-const and ipa-modref that both wants to check
> whether given memory access can interfere with memory acesses before function
> call or after function return.
>
> I pulled the logic out to refs_local_or_readonly_memory_p for references and
> points_to_local_or_readonly_memory_p for pointers. It is in ipa-fnsummary.c
> because I have incremental patches to track this info about function parameter
> so we can ignore dereferences from parameters that are local or readonly in
> modref oracle.
>
> I am not sure this is right placement. We could also move it to more general
> place, ipa-utils or some of gimple infrastructure.
> The extra includes in ipa-modref will however soon be necessary.
>
> Bootstrapped/regtested x86_64-linux, OK?
>
> Honza
>
> * ipa-fnsummary.c (refs_local_or_readonly_memory_p): New function.
> (points_to_local_or_readonly_memory_p): New function.
> * ipa-fnsummary.h (refs_local_or_readonly_memory_p,
> points_to_local_or_readonly_memory_p): Declare.
> * ipa-modref.c: Include value-range.h, ipa-prop.h and ipa-fnsummary.h
> (record_access_p): Use refs_local_or_readonly_memory_p.
> * ipa-pure-const.c (check_op): Likewise.
>
> * testsuite/gcc.dg/tree-ssa/local-pure-const.c: Update template.
> diff --git a/gcc/ipa-fnsummary.c b/gcc/ipa-fnsummary.c
> index 86d01addb44..ce168230105 100644
> --- a/gcc/ipa-fnsummary.c
> +++ b/gcc/ipa-fnsummary.c
> @@ -2430,6 +2433,51 @@ fp_expression_p (gimple *stmt)
> return false;
> }
>
> +/* Return true if T references memory location that is local
> + for the function (that means, dead after return) or read-only. */
> +
> +bool
> +refs_local_or_readonly_memory_p (tree t)
> +{
> + /* Non-escaping memory is fine */
> + t = get_base_address (t);
> + if ((TREE_CODE (t) == MEM_REF
> + || TREE_CODE (t) == TARGET_MEM_REF))
> + return points_to_local_or_readonly_memory_p (TREE_OPERAND (t, 0));
> +
> + /* Automatic variables are fine. */
> + if (DECL_P (t)
> + && auto_var_in_fn_p (t, current_function_decl))
> + return true;
> +
> + /* Read-only variables are fine. */
> + if (DECL_P (t) && TREE_READONLY (t))
> + return true;
> +
> + return false;
> +}
> +
> +/* Return true if T is a pointer pointing to memory location that is local
> + for the function (that means, dead after return) or read-only. */
> +
> +bool
> +points_to_local_or_readonly_memory_p (tree t)
> +{
> + /*if (!POINTER_TYPE_P (TREE_TYPE (t)))
> + return false; */
remove ^^^
> + STRIP_NOPS (t);
This wasn't in the original code - did you really run into (long)&x or what?
> + /* See if memory location is clearly invalid. */
> + if (TREE_CODE (t) == INTEGER_CST)
> + return flag_delete_null_pointer_checks;
> + if (TREE_CODE (t) == SSA_NAME)
> + return SSA_NAME_POINTS_TO_READONLY_MEMORY (t)
> + || !ptr_deref_may_alias_global_p (t);
> + if (TREE_CODE (t) == ADDR_EXPR)
> + return refs_local_or_readonly_memory_p (TREE_OPERAND (t, 0));
> + return false;
> +}
> +
> +
> /* Analyze function body for NODE.
> EARLY indicates run from early optimization pipeline. */
>
> diff --git a/gcc/ipa-fnsummary.h b/gcc/ipa-fnsummary.h
> index c6ddc9f3199..a3223d06acc 100644
> --- a/gcc/ipa-fnsummary.h
> +++ b/gcc/ipa-fnsummary.h
> @@ -357,6 +357,8 @@ void estimate_ipcp_clone_size_and_time (struct
> cgraph_node *,
> void ipa_merge_fn_summary_after_inlining (struct cgraph_edge *edge);
> void ipa_update_overall_fn_summary (struct cgraph_node *node, bool reset =
> true);
> void compute_fn_summary (struct cgraph_node *, bool);
> +bool refs_local_or_readonly_memory_p (tree);
> +bool points_to_local_or_readonly_memory_p (tree);
>
>
> void evaluate_properties_for_edge (struct cgraph_edge *e,
> diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
> index af0b710333e..d1b091ae29e 100644
> --- a/gcc/ipa-modref.c
> +++ b/gcc/ipa-modref.c
> @@ -62,6 +62,9 @@ along with GCC; see the file COPYING3. If not see
> #include "calls.h"
> #include "ipa-modref-tree.h"
> #include "ipa-modref.h"
> +#include "value-range.h"
> +#include "ipa-prop.h"
> +#include "ipa-fnsummary.h"
>
> /* Class (from which there is one global instance) that holds modref
> summaries
> for all analyzed functions. */
> @@ -317,36 +415,12 @@ record_access_lto (modref_records_lto *tt, ao_ref *ref)
> static bool
> record_access_p (tree expr)
> {
> - /* Non-escaping memory is fine */
> - tree t = get_base_address (expr);
> - if (t && (INDIRECT_REF_P (t)
> - || TREE_CODE (t) == MEM_REF
> - || TREE_CODE (t) == TARGET_MEM_REF)
> - && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME
> - && !ptr_deref_may_alias_global_p (TREE_OPERAND (t, 0)))
> + if (refs_local_or_readonly_memory_p (expr))
> {
> if (dump_file)
> - fprintf (dump_file, " - Non-escaping memory, ignoring.\n");
> + fprintf (dump_file, " - Read-only or local, ignoring.\n");
> return false;
> }
> -
> - /* Automatic variables are fine. */
> - if (DECL_P (t)
> - && auto_var_in_fn_p (t, current_function_decl))
> - {
> - if (dump_file)
> - fprintf (dump_file, " - Automatic variable, ignoring.\n");
> - return false;
> - }
> -
> - /* Read-only variables are fine. */
> - if (DECL_P (t) && TREE_READONLY (t))
> - {
> - if (dump_file)
> - fprintf (dump_file, " - Read-only variable, ignoring.\n");
> - return false;
> - }
> -
> return true;
> }
>
> diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c
> index 564c6629c92..bdbccd010dc 100644
> --- a/gcc/ipa-pure-const.c
> +++ b/gcc/ipa-pure-const.c
> @@ -381,13 +381,11 @@ check_op (funct_state local, tree t, bool
> checking_write)
> fprintf (dump_file, " Volatile indirect ref is not const/pure\n");
> return;
> }
> - else if (t
> - && (INDIRECT_REF_P (t) || TREE_CODE (t) == MEM_REF)
> - && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME
> - && !ptr_deref_may_alias_global_p (TREE_OPERAND (t, 0)))
> + else if (refs_local_or_readonly_memory_p (t))
> {
> if (dump_file)
> - fprintf (dump_file, " Indirect ref to local memory is OK\n");
> + fprintf (dump_file, " Indirect ref to local or readonly "
> + "memory is OK\n");
> return;
> }
> else if (checking_write)
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/local-pure-const.c
> b/gcc/testsuite/gcc.dg/tree-ssa/local-pure-const.c
> index 3c358e01393..6746758ca88 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/local-pure-const.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/local-pure-const.c
> @@ -12,5 +12,5 @@ t(int a, int b, int c)
> p = &c;
> return *p;
> }
> -/* { dg-final { scan-tree-dump-times "local memory is OK" 1
> "local-pure-const1"} } */
> +/* { dg-final { scan-tree-dump-times "local or readonly memory is OK" 1
> "local-pure-const1"} } */
> /* { dg-final { scan-tree-dump-times "found to be const" 1
> "local-pure-const1"} } */
