From 5fb4027fae1839cabbea75112c31bd89d46d2af0 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Thu, 22 Oct 2020 17:23:25 +0200 Subject: [PATCH] [gdb/symtab] Make find_block_in_blockvector more robust While working on PR25858 I noticed that the following trigger patch: ... @@ -2918,6 +2918,7 @@ find_pc_sect_compunit_symtab const struct blockvector *bv; bv = COMPUNIT_BLOCKVECTOR (cust); + (volatile int)blockvector_contains_pc (bv, pc); b = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK); if (BLOCK_START (b) <= pc ... triggers this assert, which checks that the returned block indeed contains pc: ... @@ -170,7 +170,10 @@ find_block_in_blockvector { b = BLOCKVECTOR_BLOCK (bl, bot); if (BLOCK_END (b) > pc) - return b; + { + gdb_assert (BLOCK_START (b) <= pc); + return b; + } bot--; } ... when running test-case gdb.ada/bp_c_mixed_case.exp. It's possible that the trigger patch breaks an undocumented invariant: I've tried a build and test run without the trigger patch and did not manage to trigger the assert. For robustness-sake, fix the assert by bailing out if 'BLOCK_START (b) <= pc' doesn't hold. Tested on x86_64-linux. gdb/ChangeLog: 2020-10-22 Tom de Vries * block.c (find_block_in_blockvector): Make sure the returned block contains pc. --- gdb/ChangeLog | 5 +++++ gdb/block.c | 2 ++ 2 files changed, 7 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index bda88839b8d..76c5e9e8af3 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2020-10-22 Tom de Vries + + * block.c (find_block_in_blockvector): Make sure the returned block + contains pc. + 2020-10-22 Simon Marchi PR gdb/26693 diff --git a/gdb/block.c b/gdb/block.c index 597d6d5d875..070d3f77697 100644 --- a/gdb/block.c +++ b/gdb/block.c @@ -166,6 +166,8 @@ find_block_in_blockvector (const struct blockvector *bl, CORE_ADDR pc) while (bot >= STATIC_BLOCK) { b = BLOCKVECTOR_BLOCK (bl, bot); + if (!(BLOCK_START (b) <= pc)) + return NULL; if (BLOCK_END (b) > pc) return b; bot--; -- 2.30.2