On February 16, 2019 8:12:34 AM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>Hi!
>
>Both the C and C++ standard guarantee that the argc argument to main is
>non-negative, the following patch sets (or adjusts) the corresponding
>SSA_NAME_RANGE_INFO. While main is just one, with IPA VRP it can also
>propagate etc. I had to change one testcase because it started
>optimizing
>it better (the test has been folded away), so no sinking was done.
Can we handle this in _nonnegative_p? Also make it work independent of
langhooks by looking up the translation unit decl from cfun via walking
contexts?
Is this a regression?
Richard.
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
>2019-02-16 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/89350
> * gimple-ssa-evrp.c: Include tree-dfa.h and langhooks.h.
> (maybe_set_main_argc_range): New function.
> (execute_early_vrp): Call it.
>
> * gcc.dg/tree-ssa/vrp122.c: New test.
> * gcc.dg/tree-ssa/ssa-sink-3.c (main): Rename to ...
> (bar): ... this.
>
>--- gcc/gimple-ssa-evrp.c.jj 2019-01-01 12:37:15.712998659 +0100
>+++ gcc/gimple-ssa-evrp.c 2019-02-15 09:49:56.768534668 +0100
>@@ -41,6 +41,8 @@ along with GCC; see the file COPYING3.
> #include "tree-cfgcleanup.h"
> #include "vr-values.h"
> #include "gimple-ssa-evrp-analyze.h"
>+#include "tree-dfa.h"
>+#include "langhooks.h"
>
> class evrp_folder : public substitute_and_fold_engine
> {
>@@ -291,6 +293,39 @@ evrp_dom_walker::cleanup (void)
> evrp_folder.vr_values->cleanup_edges_and_switches ();
> }
>
>+/* argc in main in C/C++ is guaranteed to be non-negative. Adjust the
>+ range info for it. */
>+
>+static void
>+maybe_set_main_argc_range (void)
>+{
>+ if (!DECL_ARGUMENTS (current_function_decl)
>+ || !(lang_GNU_C () || lang_GNU_CXX () || lang_GNU_OBJC ()))
>+ return;
>+
>+ tree argc = DECL_ARGUMENTS (current_function_decl);
>+ if (TYPE_MAIN_VARIANT (TREE_TYPE (argc)) != integer_type_node)
>+ return;
>+
>+ argc = ssa_default_def (cfun, argc);
>+ if (argc == NULL_TREE)
>+ return;
>+
>+ wide_int min, max;
>+ value_range_kind kind = get_range_info (argc, &min, &max);
>+ if (kind == VR_VARYING)
>+ {
>+ min = wi::zero (TYPE_PRECISION (integer_type_node));
>+ max = wi::to_wide (TYPE_MAX_VALUE (integer_type_node));
>+ }
>+ else if (kind == VR_RANGE && wi::neg_p (min) && !wi::neg_p (max))
>+ min = wi::zero (TYPE_PRECISION (integer_type_node));
>+ else
>+ return;
>+
>+ set_range_info (argc, VR_RANGE, min, max);
>+}
>+
>/* Main entry point for the early vrp pass which is a simplified
>non-iterative
>version of vrp where basic blocks are visited in dominance order.
>Value
> ranges discovered in early vrp will also be used by ipa-vrp. */
>@@ -307,6 +342,10 @@ execute_early_vrp ()
> scev_initialize ();
> calculate_dominance_info (CDI_DOMINATORS);
>
>+ /* argc in main in C/C++ is guaranteed to be non-negative. */
>+ if (MAIN_NAME_P (DECL_NAME (current_function_decl)))
>+ maybe_set_main_argc_range ();
>+
> /* Walk stmts in dominance order and propagate VRP. */
> evrp_dom_walker walker;
> walker.walk (ENTRY_BLOCK_PTR_FOR_FN (cfun));
>--- gcc/testsuite/gcc.dg/tree-ssa/vrp122.c.jj 2019-02-15
>09:54:07.016357759 +0100
>+++ gcc/testsuite/gcc.dg/tree-ssa/vrp122.c 2019-02-15
>09:53:59.299486561 +0100
>@@ -0,0 +1,14 @@
>+/* PR tree-optimization/89350 */
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -fdump-tree-optimized" } */
>+/* { dg-final { scan-tree-dump-not "link_error \\\(" "optimized" } }
>*/
>+
>+extern void link_error (void);
>+
>+int
>+main (int argc, const char *argv[])
>+{
>+ if (argc < 0)
>+ link_error ();
>+ return 0;
>+}
>--- gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-3.c.jj 2015-05-29
>15:03:44.947546711 +0200
>+++ gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-3.c 2019-02-16
>08:04:29.951126611 +0100
>@@ -2,7 +2,7 @@
> /* { dg-options "-O2 -fdump-tree-sink-stats" } */
> extern void foo(int a);
> int
>-main (int argc)
>+bar (int argc)
> {
> int a;
> a = argc + 1;
>
> Jakub
