From 991656092f78eeab2a48fdbacf4e1f08567badaf Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Sat, 9 Jan 2021 10:49:38 +0100 Subject: [PATCH] tree-cfg: Allow enum types as result of POINTER_DIFF_EXPR [PR98556] As conversions between signed integers and signed enums with the same precision are useless in GIMPLE, it seems strange that we require that POINTER_DIFF_EXPR result must be INTEGER_TYPE. If we really wanted to require that, we'd need to change the gimplifier to ensure that, which it isn't the case on the following testcase. What is going on during the gimplification is that when we have the (enum T) (p - q) cast, it is stripped through /* Strip away as many useless type conversions as possible at the toplevel. */ STRIP_USELESS_TYPE_CONVERSION (*expr_p); and when the MODIFY_EXPR is gimplified, the *to_p has enum T type, while *from_p has intptr_t type and as there is no conversion in between, we just create GIMPLE_ASSIGN from that. 2021-01-09 Jakub Jelinek PR c++/98556 * tree-cfg.c (verify_gimple_assign_binary): Allow lhs of POINTER_DIFF_EXPR to be any integral type. * c-c++-common/pr98556.c: New test. --- gcc/testsuite/c-c++-common/pr98556.c | 11 +++++++++++ gcc/tree-cfg.c | 2 +- 2 files changed, 12 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/c-c++-common/pr98556.c diff --git a/gcc/testsuite/c-c++-common/pr98556.c b/gcc/testsuite/c-c++-common/pr98556.c new file mode 100644 index 00000000000..865957bf353 --- /dev/null +++ b/gcc/testsuite/c-c++-common/pr98556.c @@ -0,0 +1,11 @@ +/* PR c++/98556 */ +/* { dg-do compile } */ +/* { dg-options "-O0" } */ + +enum T { E = -__LONG_MAX__ - 1 }; + +enum T +foo (char *p, char *q) +{ + return (enum T) (p - q); +} diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c index cea7f920e43..75d814bd121 100644 --- a/gcc/tree-cfg.c +++ b/gcc/tree-cfg.c @@ -3940,7 +3940,7 @@ verify_gimple_assign_binary (gassign *stmt) /* Because we special-case pointers to void we allow difference of arbitrary pointers with the same mode. */ || TYPE_MODE (rhs1_type) != TYPE_MODE (rhs2_type) - || TREE_CODE (lhs_type) != INTEGER_TYPE + || !INTEGRAL_TYPE_P (lhs_type) || TYPE_UNSIGNED (lhs_type) || TYPE_PRECISION (lhs_type) != TYPE_PRECISION (rhs1_type)) { -- 2.30.2