Hi,
The problem here is the strlen optimization tries to remove a null
character store as we already have done it but it does it for a
volatile store which is not a valid thing to do.
This patch fixes the problem by ignoring statements which have
volatile operands.
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
Thanks,
Andrew Pinski
ChangeLog:
* tree-ssa-strlen.c (strlen_optimize_stmt): Don't look at statements
which have volatile operands.
testsuite/ChangeLog:
* gcc.dg/tree-ssa/strlen-1.c: New testcase.
Index: gcc/tree-ssa-strlen.c
===================================================================
--- gcc/tree-ssa-strlen.c (revision 190993)
+++ gcc/tree-ssa-strlen.c (working copy)
@@ -1782,7 +1782,8 @@ strlen_optimize_stmt (gimple_stmt_iterat
break;
}
}
- else if (is_gimple_assign (stmt))
+ else if (is_gimple_assign (stmt)
+ && !gimple_has_volatile_ops (stmt))
{
tree lhs = gimple_assign_lhs (stmt);
Index: gcc/testsuite/gcc.dg/tree-ssa/strlen-1.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/strlen-1.c (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/strlen-1.c (revision 0)
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+extern const unsigned long base;
+static inline void wreg(unsigned char val, unsigned long addr)
__attribute__((always_inline));
+static inline void wreg(unsigned char val, unsigned long addr)
+{
+ *((volatile unsigned char *) (__SIZE_TYPE__) (base + addr)) = val;
+}
+void wreg_twice(void)
+{
+ wreg(0, 42);
+ wreg(0, 42);
+}
+
+/* We should not remove the second null character store to (base+42) address.
*/
+/* { dg-final { scan-tree-dump-times " ={v} 0;" 2 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
