* [PATCH] Improve PR78655
@ 2018-08-20 13:59 Richard Biener
0 siblings, 0 replies; only message in thread
From: Richard Biener @ 2018-08-20 13:59 UTC (permalink / raw)
To: gcc-patches
The following implements parts of the suggested transforms in PR78655
by making code already in VRP actually trigger. The patch doesn't
handle
void bar (int *x, int a)
{
if (a != 0)
{
int *p = x + a;
if (p == 0)
link_error ();
}
}
because a gets promoted to sizetype and the multiplied by 4 which
has defined overflow and thus gets us zero in the range for the
addend again.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2018-08-20 Richard Biener <rguenther@suse.de>
PR tree-optimization/78655
* tree-vrp.c (extract_range_from_binary_expr_1): Make
pointer + offset nonnull if either operand is nonnull work.
* gcc.dg/tree-ssa/evrp11.c: New testcase.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/evrp11.c b/gcc/testsuite/gcc.dg/tree-ssa/evrp11.c
new file mode 100644
index 00000000000..f1373bd8683
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/evrp11.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp" } */
+
+extern void link_error ();
+
+void foo (int *x)
+{
+ int *p = x + 1;
+ if (p == 0)
+ link_error ();
+}
+
+void bar (char *x, int a)
+{
+ if (a != 0)
+ {
+ char *p = x + a;
+ if (p == 0)
+ link_error ();
+ }
+}
+
+/* { dg-final { scan-tree-dump-not "link_error" "evrp" } } */
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index d553a254878..2ddb0c2c197 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -1437,6 +1437,7 @@ extract_range_from_binary_expr_1 (value_range *vr,
&& code != PLUS_EXPR
&& code != MINUS_EXPR
&& code != RSHIFT_EXPR
+ && code != POINTER_PLUS_EXPR
&& (vr0.type == VR_VARYING
|| vr1.type == VR_VARYING
|| vr0.type != vr1.type
@@ -1467,7 +1468,11 @@ extract_range_from_binary_expr_1 (value_range *vr,
{
/* For pointer types, we are really only interested in asserting
whether the expression evaluates to non-NULL. */
- if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1))
+ if (range_is_nonnull (&vr0)
+ || range_is_nonnull (&vr1)
+ || (vr1.type == VR_RANGE
+ && !symbolic_range_p (&vr1)
+ && !range_includes_zero_p (vr1.min, vr1.max)))
set_value_range_to_nonnull (vr, expr_type);
else if (range_is_null (&vr0) && range_is_null (&vr1))
set_value_range_to_null (vr, expr_type);
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2018-08-20 13:59 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-08-20 13:59 [PATCH] Improve PR78655 Richard Biener
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).