Here, we got ourselves into infinite recursion in fold, resulting in a stack
overflow. I believe the crux is that we're passing UNARY_PLUS_EXPR, a C++-only
code, into fold which can't really fold e.g. 1 + UNARY_PLUS_EXPR <1>. I think
cp_fold should be able to fold this to 2, but currently is not. But I noticed
that cxx_eval_constant_expression seems to handle this:
if (tcode == UNARY_PLUS_EXPR)
r = fold_convert (TREE_TYPE (t), op);
so I tweaked cp_fold to do something similar. With this patch we're able to
fold the expression above properly and fold doesn't run into infinite looping
anymore.
I made the test a run-time test to sanity-check we're generating the correct
value.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2016-03-10 Marek Polacek <pola...@redhat.com>
PR c++/70153
* cp-gimplify.c (cp_fold): Handle UNARY_PLUS_EXPR.
* g++.dg/delayedfold/unary-plus1.C: New test.
diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
index 6af3760..db23efe 100644
--- gcc/cp/cp-gimplify.c
+++ gcc/cp/cp-gimplify.c
@@ -2009,6 +2009,8 @@ cp_fold (tree x)
else
x = fold_build1_loc (loc, code, TREE_TYPE (x), op0);
}
+ else if (code == UNARY_PLUS_EXPR)
+ x = fold_convert (TREE_TYPE (x), op0);
else
x = fold (x);
diff --git gcc/testsuite/g++.dg/delayedfold/unary-plus1.C
gcc/testsuite/g++.dg/delayedfold/unary-plus1.C
index e69de29..5ebee22 100644
--- gcc/testsuite/g++.dg/delayedfold/unary-plus1.C
+++ gcc/testsuite/g++.dg/delayedfold/unary-plus1.C
@@ -0,0 +1,15 @@
+// PR c++/70153
+// { dg-do run }
+
+unsigned long long int
+foo (unsigned long long int i)
+{
+ return 2ULL * ((1 + (unsigned long int) +1) * i);
+}
+
+int
+main (void)
+{
+ if (foo (3ULL) != 12ULL)
+ __builtin_abort ();
+}
Marek
