From 7b5925a816f6548e4e49a7947ecedc612d260947 Mon Sep 17 00:00:00 2001 From: Pierre-Marie de Rodat Date: Fri, 9 Feb 2018 14:02:37 +0000 Subject: [PATCH] DWARF: no location for non-definition DECLs with non-trivial DECL_VALUE_EXPR This patch restricts the set of cases in which we allow the generation of location attributes for variables that are not defined in the current unit. For such variables with complex DECL_VALUE_EXPR trees, generating a location attribute can end up creating relocations to text symbols in the debug section of LTO object files, which is not valid. gcc/ PR lto/84213 * dwarf2out.c (is_trivial_indirect_ref): New function. (dwarf2out_late_global_decl): Do not generate a location attribute for variables that have a non-trivial DECL_VALUE_EXPR and that are not defined in the current unit. From-SVN: r257526 --- gcc/ChangeLog | 8 ++++++++ gcc/dwarf2out.c | 31 +++++++++++++++++++++++++++---- 2 files changed, 35 insertions(+), 4 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 858ad9d..1d4a3ee 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2018-02-09 Pierre-Marie de Rodat + + PR lto/84213 + * dwarf2out.c (is_trivial_indirect_ref): New function. + (dwarf2out_late_global_decl): Do not generate a location + attribute for variables that have a non-trivial DECL_VALUE_EXPR + and that are not defined in the current unit. + 2018-02-09 Eric Botcazou * optabs.c (prepare_cmp_insn): Try harder to emit a direct comparison diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index 749c7e3..984df9f 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -26235,6 +26235,23 @@ dwarf2out_early_global_decl (tree decl) symtab->global_info_ready = save; } +/* Return whether EXPR is an expression with the following pattern: + INDIRECT_REF (NOP_EXPR (INTEGER_CST)). */ + +static bool +is_trivial_indirect_ref (tree expr) +{ + if (expr == NULL_TREE || TREE_CODE (expr) != INDIRECT_REF) + return false; + + tree nop = TREE_OPERAND (expr, 0); + if (nop == NULL_TREE || TREE_CODE (nop) != NOP_EXPR) + return false; + + tree int_cst = TREE_OPERAND (nop, 0); + return int_cst != NULL_TREE && TREE_CODE (int_cst) == INTEGER_CST; +} + /* Output debug information for global decl DECL. Called from toplev.c after compilation proper has finished. */ @@ -26259,11 +26276,17 @@ dwarf2out_late_global_decl (tree decl) if (die) { /* We get called via the symtab code invoking late_global_decl - for symbols that are optimized out. Do not add locations - for those, except if they have a DECL_VALUE_EXPR, in which case - they are relevant for debuggers. */ + for symbols that are optimized out. + + Do not add locations for those, except if they have a + DECL_VALUE_EXPR, in which case they are relevant for debuggers. + Still don't add a location if the DECL_VALUE_EXPR is not a trivial + INDIRECT_REF expression, as this could generate relocations to + text symbols in LTO object files, which is invalid. */ varpool_node *node = varpool_node::get (decl); - if ((! node || ! node->definition) && ! DECL_HAS_VALUE_EXPR_P (decl)) + if ((! node || ! node->definition) + && ! (DECL_HAS_VALUE_EXPR_P (decl) + && is_trivial_indirect_ref (DECL_VALUE_EXPR (decl)))) tree_add_const_value_attribute_for_decl (die, decl); else add_location_or_const_value_attribute (die, decl, false); -- 2.7.4