From 8156cfaa4c45f1249bbdda29d04b4fef84b7eafe Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 19 Nov 2020 20:02:41 +0100 Subject: [PATCH] c, tree: Fix ICE from get_parm_array_spec [PR97860] The C and C++ FEs handle zero sized arrays differently, C uses NULL TYPE_MAX_VALUE on non-NULL TYPE_DOMAIN on complete ARRAY_TYPEs with bitsize_zero_node TYPE_SIZE, while C++ FE likes to set TYPE_MAX_VALUE to the largest value (and min to the lowest). Martin has used array_type_nelts in get_parm_array_spec where the function on the C form of [0] arrays returns error_mark_node and the code crashes soon afterwards. The following patch teaches array_type_nelts about this (e.g. dwarf2out already handles that as [0]). While it will change what is_empty_type returns for certain types (e.g. struct S { int a[0]; };), as those types occupy zero bits in C, it should make an ABI difference. So, the tree.c change makes the c-decl.c code handle the [0] arrays like any other constant extents, and the c-decl.c change just makes sure that if we'd run into error_mark_node e.g. from the VLA expressions, we don't crash on those. 2020-11-19 Jakub Jelinek PR c/97860 * tree.c (array_type_nelts): For complete arrays with zero min and NULL max and zero size return -1. * c-decl.c (get_parm_array_spec): Bail out of nelts is error_operand_p. * gcc.dg/pr97860.c: New test. --- gcc/c/c-decl.c | 2 ++ gcc/testsuite/gcc.dg/pr97860.c | 11 +++++++++++ gcc/tree.c | 12 +++++++++++- 3 files changed, 24 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr97860.c diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c index d348e39..1b02240 100644 --- a/gcc/c/c-decl.c +++ b/gcc/c/c-decl.c @@ -5775,6 +5775,8 @@ get_parm_array_spec (const struct c_parm *parm, tree attrs) type = TREE_TYPE (type)) { tree nelts = array_type_nelts (type); + if (error_operand_p (nelts)) + return attrs; if (TREE_CODE (nelts) != INTEGER_CST) { /* Each variable VLA bound is represented by the dollar diff --git a/gcc/testsuite/gcc.dg/pr97860.c b/gcc/testsuite/gcc.dg/pr97860.c new file mode 100644 index 0000000..04c0f19 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr97860.c @@ -0,0 +1,11 @@ +/* PR c/97860 */ +/* { dg-do compile } */ +/* { dg-options "" } */ + +void +foo (int n) +{ + typedef int T[0]; + typedef T V[n]; + void bar (V); +} diff --git a/gcc/tree.c b/gcc/tree.c index 0043855..531fe96 100644 --- a/gcc/tree.c +++ b/gcc/tree.c @@ -3483,7 +3483,17 @@ array_type_nelts (const_tree type) /* TYPE_MAX_VALUE may not be set if the array has unknown length. */ if (!max) - return error_mark_node; + { + /* zero sized arrays are represented from C FE as complete types with + NULL TYPE_MAX_VALUE and zero TYPE_SIZE, while C++ FE represents + them as min 0, max -1. */ + if (COMPLETE_TYPE_P (type) + && integer_zerop (TYPE_SIZE (type)) + && integer_zerop (min)) + return build_int_cst (TREE_TYPE (min), -1); + + return error_mark_node; + } return (integer_zerop (min) ? max -- 2.7.4