public inbox for gdb-prs@sourceware.org help / color / mirror / Atom feed
* [Bug breakpoints/27394] New: Breakpoint set on vector code but not serial code within a lexical scope @ 2021-02-11 0:16 i at maskray dot me 2021-02-11 0:19 ` [Bug breakpoints/27394] Breakpoint set on vector code but not on " i at maskray dot me ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: i at maskray dot me @ 2021-02-11 0:16 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=27394 Bug ID: 27394 Summary: Breakpoint set on vector code but not serial code within a lexical scope Product: gdb Version: unknown Status: UNCONFIRMED Severity: normal Priority: P2 Component: breakpoints Assignee: unassigned at sourceware dot org Reporter: i at maskray dot me Target Milestone: --- int Foo(const int iterations, const int initial) { static int val = initial; for (int i = 0; i <= iterations; ++i) val += (i % 2 ? 50 : 25) * i; // If you set a breakpoint on this line, it will not get hit return val; } int main(int argc, char**) { return Foo(4 + argc, 5 + argc); } clang++ -g -fno-inline -O2 a.cc # g++ -g -fno-inline -O3 a.cc is similar. clang enables vectorization with -O2 gdb ./a.out -batch -ex 'b 5' -ex 'r' The breakpoint is not triggered. (lldb has the same problem.) The problem is that we have a vector code path (smaller address) and a serial code path (larger address) under the same lexical scope. The serial code path does not get a breakpoint. gdb/linespec.c:2173 has such a comment /* For optimized code, the compiler can scatter one source line across disjoint ranges of PC values, even when no duplicate functions or inline functions are involved. For example, 'for (;;)' inside a non-template, non-inline, and non-ctor-or-dtor function can result in two PC ranges. In this case, we don't want to set a breakpoint on the first PC of each range. To filter such cases, we use containing blocks -- for each PC found above, we see if there are other PCs that are in the same block. If yes, the other PCs are filtered out. */ intermediate_results.size() is 4, matching the output of % llvm-dwarfdump -debug-line ./a.out | grep ' 5 .*is_stmt' # loop preheader for the vector code path 0x00000000004011e9 5 13 1 0 0 is_stmt 0x00000000004012ba 5 13 1 0 0 is_stmt # loop preheader for the serial code path 0x0000000000401360 5 13 1 0 0 is_stmt 0x0000000000401377 5 9 1 0 0 is_stmt blocks[*] values are the same, presumably because after considering DW_TAG_inlined_subroutine/DW_TAG_lexical_block (what else?), the four addresses are in the same scope. After deduplication, only the first address gets a breakpoint. -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug breakpoints/27394] Breakpoint set on vector code but not on serial code within a lexical scope 2021-02-11 0:16 [Bug breakpoints/27394] New: Breakpoint set on vector code but not serial code within a lexical scope i at maskray dot me @ 2021-02-11 0:19 ` i at maskray dot me 2021-02-12 1:20 ` ctice42 at gmail dot com ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: i at maskray dot me @ 2021-02-11 0:19 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=27394 Fangrui Song <i at maskray dot me> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|Breakpoint set on vector |Breakpoint set on vector |code but not serial code |code but not on serial code |within a lexical scope |within a lexical scope -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug breakpoints/27394] Breakpoint set on vector code but not on serial code within a lexical scope 2021-02-11 0:16 [Bug breakpoints/27394] New: Breakpoint set on vector code but not serial code within a lexical scope i at maskray dot me 2021-02-11 0:19 ` [Bug breakpoints/27394] Breakpoint set on vector code but not on " i at maskray dot me @ 2021-02-12 1:20 ` ctice42 at gmail dot com 2021-02-19 0:00 ` dblaikie at gmail dot com 2024-01-09 17:24 ` ssbssa at sourceware dot org 3 siblings, 0 replies; 5+ messages in thread From: ctice42 at gmail dot com @ 2021-02-12 1:20 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=27394 ctice42 at gmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ctice42 at gmail dot com -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug breakpoints/27394] Breakpoint set on vector code but not on serial code within a lexical scope 2021-02-11 0:16 [Bug breakpoints/27394] New: Breakpoint set on vector code but not serial code within a lexical scope i at maskray dot me 2021-02-11 0:19 ` [Bug breakpoints/27394] Breakpoint set on vector code but not on " i at maskray dot me 2021-02-12 1:20 ` ctice42 at gmail dot com @ 2021-02-19 0:00 ` dblaikie at gmail dot com 2024-01-09 17:24 ` ssbssa at sourceware dot org 3 siblings, 0 replies; 5+ messages in thread From: dblaikie at gmail dot com @ 2021-02-19 0:00 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=27394 David Blaikie <dblaikie at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |dblaikie at gmail dot com -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug breakpoints/27394] Breakpoint set on vector code but not on serial code within a lexical scope 2021-02-11 0:16 [Bug breakpoints/27394] New: Breakpoint set on vector code but not serial code within a lexical scope i at maskray dot me ` (2 preceding siblings ...) 2021-02-19 0:00 ` dblaikie at gmail dot com @ 2024-01-09 17:24 ` ssbssa at sourceware dot org 3 siblings, 0 replies; 5+ messages in thread From: ssbssa at sourceware dot org @ 2024-01-09 17:24 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=27394 Hannes Domani <ssbssa at sourceware dot org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ssbssa at sourceware dot org --- Comment #1 from Hannes Domani <ssbssa at sourceware dot org> --- I think this is a duplicate of PR24032, but I'm not completely sure. -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-01-09 17:24 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-02-11 0:16 [Bug breakpoints/27394] New: Breakpoint set on vector code but not serial code within a lexical scope i at maskray dot me 2021-02-11 0:19 ` [Bug breakpoints/27394] Breakpoint set on vector code but not on " i at maskray dot me 2021-02-12 1:20 ` ctice42 at gmail dot com 2021-02-19 0:00 ` dblaikie at gmail dot com 2024-01-09 17:24 ` ssbssa at sourceware dot org
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).