Jeff approved an older version of this (as a separate
unittests/test-folding.c):
https://gcc.gnu.org/ml/gcc-patches/2015-10/msg03305.html
> OK if/when prereqs are approved. Minor twiddling if we end up
> moving it elsewhere or standardizing/reducing header files
> is pre-approved.
gcc/ChangeLog:
* fold-const.c: Include "selftest.h".
(class tree_folding_test): New test subclass.
(tree_folding_test, arithmetic_folding): New selftest.
---
gcc/fold-const.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 698062e..27c9216 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -74,6 +74,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-into-ssa.h"
#include "md5.h"
#include "case-cfn-macros.h"
+#include "selftest.h"
#ifndef LOAD_EXTEND_OP
#define LOAD_EXTEND_OP(M) UNKNOWN
@@ -14423,3 +14424,68 @@ c_getstr (tree src)
return TREE_STRING_POINTER (src) + tree_to_uhwi (offset_node);
}
+
+#if CHECKING_P
+
+namespace {
+
+/* A test fixture for writing tests of folding trees. */
+class tree_folding_test : public ::selftest::test
+{
+ protected:
+ void
+ assert_binop_folds_to_const (tree lhs, enum tree_code code, tree rhs,
+ tree constant)
+ {
+ EXPECT_EQ (constant, fold_build2 (code, TREE_TYPE (lhs), lhs, rhs));
+ }
+
+ void
+ assert_binop_folds_to_nonlvalue (tree lhs, enum tree_code code, tree rhs,
+ tree wrapped_expr)
+ {
+ tree result = fold_build2 (code, TREE_TYPE (lhs), lhs, rhs);
+ EXPECT_NE (wrapped_expr, result);
+ EXPECT_EQ (NON_LVALUE_EXPR, TREE_CODE (result));
+ EXPECT_EQ (wrapped_expr, TREE_OPERAND (result, 0));
+ }
+};
+
+TEST_F (tree_folding_test, arithmetic_folding)
+{
+ tree type = integer_type_node;
+ tree x = create_tmp_var_raw (type, "x");
+ tree zero = build_zero_cst (type);
+ tree one = build_int_cst (type, 1);
+
+ /* Addition. */
+ /* 1 <-- (0 + 1) */
+ assert_binop_folds_to_const (zero, PLUS_EXPR, one,
+ one);
+ assert_binop_folds_to_const (one, PLUS_EXPR, zero,
+ one);
+
+ /* (nonlvalue)x <-- (x + 0) */
+ assert_binop_folds_to_nonlvalue (x, PLUS_EXPR, zero,
+ x);
+
+ /* Subtraction. */
+ /* 0 <-- (x - x) */
+ assert_binop_folds_to_const (x, MINUS_EXPR, x,
+ zero);
+ assert_binop_folds_to_nonlvalue (x, MINUS_EXPR, zero,
+ x);
+
+ /* Multiplication. */
+ /* 0 <-- (x * 0) */
+ assert_binop_folds_to_const (x, MULT_EXPR, zero,
+ zero);
+
+ /* (nonlvalue)x <-- (x * 1) */
+ assert_binop_folds_to_nonlvalue (x, MULT_EXPR, one,
+ x);
+}
+
+} // anon namespace
+
+#endif /* CHECKING_P */
--
1.8.5.3
