From 5a96dae3efa97317540aee2a55f717aab1efe064 Mon Sep 17 00:00:00 2001 From: Pierre-Marie de Rodat Date: Tue, 10 May 2016 08:03:49 +0000 Subject: [PATCH] DWARF: add abstract origin links on lexical blocks DIEs Track from which abstract lexical block concrete ones come from in DWARF so that debuggers can inherit the former from the latter. This enables debuggers to properly handle the following case: * function Child2 is nested in a lexical block, itself nested in function Child1; * function Child1 is inlined into some call site; * function Child2 is never inlined. Here, Child2 is described in DWARF only in the abstract instance of Child1. So when debuggers decode Child1's concrete instances, they need to fetch the definition for Child2 in the corresponding abstract instance: the DW_AT_abstract_origin link on the lexical block that embeds Child1 enables them to do that. Bootstrapped and regtested on x86_64-linux. gcc/ChangeLog: * dwarf2out.c (add_abstract_origin_attribute): Adjust documentation comment. For BLOCK nodes, add a DW_AT_abstract_origin attribute that points to the DIE generated for the origin BLOCK. (gen_lexical_block_die): Call add_abstract_origin_attribute for blocks from inlined functions. gcc/testsuite/Changelog: * gcc.dg/debug/dwarf2/nested_fun.c: New testcase. From-SVN: r236065 --- gcc/ChangeLog | 9 +++ gcc/dwarf2out.c | 13 +++- gcc/testsuite/ChangeLog | 4 ++ .../gcc.dg/debug/dwarf2/nested_fun.c | 65 +++++++++++++++++++ 4 files changed, 88 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/debug/dwarf2/nested_fun.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 687ab97b450..fb9b6a7f416 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2016-05-10 Pierre-Marie de Rodat + + * dwarf2out.c (add_abstract_origin_attribute): Adjust + documentation comment. For BLOCK nodes, add a + DW_AT_abstract_origin attribute that points to the DIE generated + for the origin BLOCK. + (gen_lexical_block_die): Call add_abstract_origin_attribute for + blocks from inlined functions. + 2016-05-10 Alan Modra PR target/70947 diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index fb3f7b9eb3c..da95e19849d 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -18621,15 +18621,16 @@ add_prototyped_attribute (dw_die_ref die, tree func_type) } /* Add an 'abstract_origin' attribute below a given DIE. The DIE is found - by looking in either the type declaration or object declaration - equate table. */ + by looking in the type declaration, the object declaration equate table or + the block mapping. */ static inline dw_die_ref add_abstract_origin_attribute (dw_die_ref die, tree origin) { dw_die_ref origin_die = NULL; - if (TREE_CODE (origin) != FUNCTION_DECL) + if (TREE_CODE (origin) != FUNCTION_DECL + && TREE_CODE (origin) != BLOCK) { /* We may have gotten separated from the block for the inlined function, if we're in an exception handler or some such; make @@ -18651,6 +18652,8 @@ add_abstract_origin_attribute (dw_die_ref die, tree origin) origin_die = lookup_decl_die (origin); else if (TYPE_P (origin)) origin_die = lookup_type_die (origin); + else if (TREE_CODE (origin) == BLOCK) + origin_die = BLOCK_DIE (origin); /* XXX: Functions that are never lowered don't always have correct block trees (in the case of java, they simply have no block tree, in some other @@ -21467,6 +21470,10 @@ gen_lexical_block_die (tree stmt, dw_die_ref context_die) BLOCK_DIE (stmt) = stmt_die; old_die = NULL; } + + tree origin = block_ultimate_origin (stmt); + if (origin != NULL_TREE && origin != stmt) + add_abstract_origin_attribute (stmt_die, origin); } if (old_die) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 29a9709e6ca..f144648aae8 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2016-05-10 Pierre-Marie de Rodat + + * gcc.dg/debug/dwarf2/nested_fun.c: New testcase. + 2016-05-09 Uros Bizjak * gcc.target/i386/fabsneg-1.c New test. diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/nested_fun.c b/gcc/testsuite/gcc.dg/debug/dwarf2/nested_fun.c new file mode 100644 index 00000000000..c783ac0c11a --- /dev/null +++ b/gcc/testsuite/gcc.dg/debug/dwarf2/nested_fun.c @@ -0,0 +1,65 @@ +/* As part of inlining, a BLOCK (described as DW_TAG_lexical_block DIE's) may + be present both as an abstract instance and a concrete one in the DWARF + output. This testcase attempts to make sure that the concrete ones refer to + the abstract ones thanks to the DW_AT_abstract_origin attribute. + + Such a back-link enables debuggers to make entities present in the abstract + instance only available in concrete ones. */ + +/* { dg-options "-O2 -g -std=gnu99 -gdwarf -dA" } */ +/* { dg-final { scan-assembler-times "\\(DIE \\(0x.*\\) DW_TAG_lexical_block\\)\[^)\]*DW_AT_abstract_origin" 1 } } */ + +extern void *create (const char *); +extern void destroy (void *); +extern void do_nothing (char); + +struct string +{ + const char *data; + int lb; + int ub; +}; + +int +main (void) +{ + void *o1 = create ("foo"); + + void + parent (void) + { + { + void *o2 = create ("bar"); + + int + child (struct string s) + { + int i = s.lb; + + if (s.lb <= s.ub) + while (1) + { + char c = s.data[i - s.lb]; + do_nothing (c); + if (c == 'o') + return 1; + if (i == s.ub) + break; + ++i; + } + return 0; + } + + int r; + + r = child ((struct string) {"baz", 1, 3}); + r = child ((struct string) {"qux", 2, 4}); + r = child ((struct string) {"foobar", 1, 6}); + } + + do_nothing (0); + } + + parent (); + return 0; +} -- 2.30.2