PR61583, stage2 and stage3 compare failure due to value range loss
Alan Modra
amodra@gmail.com
Mon Jun 23 15:13:00 GMT 2014
This fixes a bootstrap compare failure on current mainline and 4.9
branch configured with --disable-checking, caused by losing value
range info when outputting debug info. Lack of value range info leads
to loop bounds not being calculated, which in turn means a "j < n"
test is not converted to "j != n". Details in the PR.
Bootstrapped and regression tested powerpc64-linux, and committed
with Jakub's approval.
gcc/
PR bootstrap/61583
* tree-vrp.c (remove_range_assertions): Do not set is_unreachable
to zero on debug statements.
gcc/testsuite/
* gcc.dg/pr61583.c: New.
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c (revision 211886)
+++ gcc/tree-vrp.c (working copy)
@@ -6523,8 +6523,9 @@ remove_range_assertions (void)
}
else
{
+ if (!is_gimple_debug (gsi_stmt (si)))
+ is_unreachable = 0;
gsi_next (&si);
- is_unreachable = 0;
}
}
}
Index: gcc/testsuite/gcc.dg/pr61583.c
===================================================================
--- gcc/testsuite/gcc.dg/pr61583.c (revision 0)
+++ gcc/testsuite/gcc.dg/pr61583.c (revision 0)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcompare-debug" } */
+
+void
+f1 (int n, int b)
+{
+ extern void f2 (int);
+ int j;
+
+ if (b)
+ n = 1;
+
+ if (n < 1)
+ __builtin_unreachable ();
+
+ for (j = 0; j < n; j++)
+ f2 (j);
+}
--
Alan Modra
Australia Development Lab, IBM
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