Hello,
this patch asserts that when we call a function with the nonnull
attribute, the corresponding argument is not zero, just like when we
dereference a pointer. Everything is under a check for
flag_delete_null_pointer_checks.
Note that this function currently gives up if the statement may throw
(because in some languages indirections may throw?), but this could
probably be relaxed a bit so my example would still work when compiled
with g++, without having to mark f1 and f2 as throw().
Bootstrap (default languages) + testsuite on x86_64-unknown-linux-gnu.
2013-10-08 Marc Glisse <marc.gli...@inria.fr>
PR tree-optimization/58480
gcc/
* tree-vrp.c (infer_value_range): Look for a nonnull attribute.
gcc/testsuite/
* gcc.dg/tree-ssa/pr58480.c: New file.
--
Marc GlisseIndex: testsuite/gcc.dg/tree-ssa/pr58480.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/pr58480.c (revision 0)
+++ testsuite/gcc.dg/tree-ssa/pr58480.c (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do compile { target { ! keeps_null_pointer_checks } } } */
+/* { dg-options "-O2 -fdump-tree-vrp1" } */
+
+extern void eliminate (void);
+extern void* f1 (void *a, void *b) __attribute__((nonnull));
+extern void* f2 (void *a, void *b) __attribute__((nonnull(2)));
+void g1 (void*p, void*q){
+ f1 (q, p);
+ if (p == 0)
+ eliminate ();
+}
+void g2 (void*p, void*q){
+ f2 (q, p);
+ if (p == 0)
+ eliminate ();
+}
+
+/* { dg-final { scan-tree-dump-times "Folding predicate\[^\\n\]*to 0" 2 "vrp1"
} } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */
Property changes on: testsuite/gcc.dg/tree-ssa/pr58480.c
___________________________________________________________________
Added: svn:keywords
## -0,0 +1 ##
+Author Date Id Revision URL
\ No newline at end of property
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property
Index: tree-vrp.c
===================================================================
--- tree-vrp.c (revision 203229)
+++ tree-vrp.c (working copy)
@@ -4493,28 +4493,58 @@ infer_value_range (gimple stmt, tree op,
/* We can only assume that a pointer dereference will yield
non-NULL if -fdelete-null-pointer-checks is enabled. */
if (flag_delete_null_pointer_checks
&& POINTER_TYPE_P (TREE_TYPE (op))
&& gimple_code (stmt) != GIMPLE_ASM)
{
unsigned num_uses, num_loads, num_stores;
count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
if (num_loads + num_stores > 0)
+ goto nonnull;
+
+ if (gimple_code (stmt) == GIMPLE_CALL)
{
- *val_p = build_int_cst (TREE_TYPE (op), 0);
- *comp_code_p = NE_EXPR;
- return true;
+ tree fntype = gimple_call_fntype (stmt);
+ tree attrs = TYPE_ATTRIBUTES (fntype);
+ for (; attrs; attrs = TREE_CHAIN (attrs))
+ {
+ attrs = lookup_attribute ("nonnull", attrs);
+
+ /* If "nonnull" wasn't specified, we know nothing about
+ the argument. */
+ if (attrs == NULL_TREE)
+ return false;
+
+ /* If "nonnull" applies to all the arguments, then ARG
+ is non-null. */
+ if (TREE_VALUE (attrs) == NULL_TREE)
+ goto nonnull;
+
+ /* Now see if op appears in the nonnull list. */
+ for (tree t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t))
+ {
+ int idx = TREE_INT_CST_LOW (TREE_VALUE (t)) - 1;
+ tree arg = gimple_call_arg (stmt, idx);
+ if (op == arg)
+ goto nonnull;
+ }
+ }
}
}
return false;
+
+nonnull:
+ *val_p = build_int_cst (TREE_TYPE (op), 0);
+ *comp_code_p = NE_EXPR;
+ return true;
}
void dump_asserts_for (FILE *, tree);
void debug_asserts_for (tree);
void dump_all_asserts (FILE *);
void debug_all_asserts (void);
/* Dump all the registered assertions for NAME to FILE. */
