For context, here are the relevant LLVM discussions: http://reviews.llvm.org/D16569 <http://reviews.llvm.org/D16569> (D16569: Emit line 0 line information for interesting 'orphan’ instructions) http://reviews.llvm.org/D9887 <http://reviews.llvm.org/D9887> [DebugInfo][FastISel] Prevent using debug location from previous block for local values
> On Feb 3, 2016, at 12:56 PM, Zachary Turner <ztur...@google.com> wrote: > > (Also, if clang is not generating code like this currently, maybe it's not a > priority, but seems worth mentioning the technique anyway, since it could > have a lot of use for these types of scenarios) > > On Wed, Feb 3, 2016 at 12:54 PM Zachary Turner <ztur...@google.com > <mailto:ztur...@google.com>> wrote: > I asked around a little bit, and it seems like you do this by hand-writing > some LLVM IR (limiting yourself to a subset that is sufficiently platform > independent) and having clang link that in alongside a regular executable. > Then call your LLVM IR function from C++ and step over it. Would that work? LLVM IR is nowhere near platform independent enough for this to be portable. Of course having a test for a single target is probably still better than having no test. I’m not sure if the effort of maintaining textual IR (which tends to change a lot) in the LLDB testsuite is worth it. Another option (not any less messy) would be to compile the test to assembler with -S insert a .loc 0 before assembling the file. -- adrian > > You'd probably need to talk to one of the LLVM guys to figure out how to do > that, but it seems like it should work. > > Assuming it does, this technique would also open the door to writing a lot of > test cases that have historically been very difficult to write (such as > unwinder tests that need frames to be constructed a specific way, etc). > > > > On Tue, Feb 2, 2016 at 5:31 PM Jim Ingham <jing...@apple.com > <mailto:jing...@apple.com>> wrote: > I don't think Clang does this right now, but Adrian says they are considering > doing it to solve some problems they have with keeping track of nested > inlines. > > Swift does it, but the compiler makes no guarantees as to when this will > happen. It isn't controlled by some pragma, builtin or whatever. So I know > some places where it will happen today, but there's no guarantee it will > continue to happen in the future. So I'll have to write a test that works > with the current compiler, and fails if the compiler changes so the relevant > function no longer has line number 0 code right after the prologue. Yuck! > > I don't think it will be any different with clang when/if it starts doing > this. > > Jim > > > > On Feb 2, 2016, at 4:14 PM, Zachary Turner <ztur...@google.com > > <mailto:ztur...@google.com>> wrote: > > > > Shouldn't it be possible to force clang to generate code like this? If so > > couldn't you write a test for this by stepping over a function call which > > has this kind of code in it? > > > > On Tue, Feb 2, 2016 at 4:11 PM Jim Ingham via lldb-commits > > <lldb-commits@lists.llvm.org <mailto:lldb-commits@lists.llvm.org>> wrote: > > Author: jingham > > Date: Tue Feb 2 18:07:23 2016 > > New Revision: 259611 > > > > URL: http://llvm.org/viewvc/llvm-project?rev=259611&view=rev > > <http://llvm.org/viewvc/llvm-project?rev=259611&view=rev> > > Log: > > The compiler may use "line number 0" to indicate compiler generated goo > > that it can't > > track a source for. When we are pushing breakpoints and stepping past > > function prologues, > > also push past code from line 0 immediately following the prologue end. > > > > <rdar://problem/23730696> > > > > Modified: > > lldb/trunk/include/lldb/Symbol/Function.h > > lldb/trunk/source/Symbol/Function.cpp > > > > Modified: lldb/trunk/include/lldb/Symbol/Function.h > > URL: > > http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Symbol/Function.h?rev=259611&r1=259610&r2=259611&view=diff > > > > <http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Symbol/Function.h?rev=259611&r1=259610&r2=259611&view=diff> > > ============================================================================== > > --- lldb/trunk/include/lldb/Symbol/Function.h (original) > > +++ lldb/trunk/include/lldb/Symbol/Function.h Tue Feb 2 18:07:23 2016 > > @@ -574,6 +574,14 @@ public: > > CompilerType > > GetCompilerType (); > > > > + //------------------------------------------------------------------ > > + /// Get the size of the prologue instructions for this function. The > > "prologue" > > + /// instructions include any instructions given line number 0 > > immediately following > > + /// the prologue end. > > + /// > > + /// @return > > + /// The size of the prologue. > > + //------------------------------------------------------------------ > > uint32_t > > GetPrologueByteSize (); > > > > > > Modified: lldb/trunk/source/Symbol/Function.cpp > > URL: > > http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Symbol/Function.cpp?rev=259611&r1=259610&r2=259611&view=diff > > > > <http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Symbol/Function.cpp?rev=259611&r1=259610&r2=259611&view=diff> > > ============================================================================== > > --- lldb/trunk/source/Symbol/Function.cpp (original) > > +++ lldb/trunk/source/Symbol/Function.cpp Tue Feb 2 18:07:23 2016 > > @@ -570,6 +570,8 @@ Function::GetPrologueByteSize () > > { > > m_flags.Set(flagsCalculatedPrologueSize); > > LineTable* line_table = m_comp_unit->GetLineTable (); > > + uint32_t prologue_end_line_idx = 0; > > + > > if (line_table) > > { > > LineEntry first_line_entry; > > @@ -578,9 +580,12 @@ Function::GetPrologueByteSize () > > { > > // Make sure the first line entry isn't already the end of > > the prologue > > addr_t prologue_end_file_addr = LLDB_INVALID_ADDRESS; > > + addr_t line_zero_end_file_addr = LLDB_INVALID_ADDRESS; > > + > > if (first_line_entry.is_prologue_end) > > { > > prologue_end_file_addr = > > first_line_entry.range.GetBaseAddress().GetFileAddress(); > > + prologue_end_line_idx = first_line_entry_idx; > > } > > else > > { > > @@ -595,6 +600,7 @@ Function::GetPrologueByteSize () > > if (line_entry.is_prologue_end) > > { > > prologue_end_file_addr = > > line_entry.range.GetBaseAddress().GetFileAddress(); > > + prologue_end_line_idx = idx; > > break; > > } > > } > > @@ -607,7 +613,7 @@ Function::GetPrologueByteSize () > > { > > // Check the first few instructions and look for one > > that has > > // a line number that's different than the first entry. > > - const uint32_t last_line_entry_idx = > > first_line_entry_idx + 6; > > + uint32_t last_line_entry_idx = first_line_entry_idx + > > 6; > > for (uint32_t idx = first_line_entry_idx + 1; idx < > > last_line_entry_idx; ++idx) > > { > > LineEntry line_entry; > > @@ -616,6 +622,7 @@ Function::GetPrologueByteSize () > > if (line_entry.line != first_line_entry.line) > > { > > prologue_end_file_addr = > > line_entry.range.GetBaseAddress().GetFileAddress(); > > + prologue_end_line_idx = idx; > > break; > > } > > } > > @@ -624,10 +631,37 @@ Function::GetPrologueByteSize () > > if (prologue_end_file_addr == LLDB_INVALID_ADDRESS) > > { > > prologue_end_file_addr = > > first_line_entry.range.GetBaseAddress().GetFileAddress() + > > first_line_entry.range.GetByteSize(); > > + prologue_end_line_idx = first_line_entry_idx; > > } > > } > > + > > const addr_t func_start_file_addr = > > m_range.GetBaseAddress().GetFileAddress(); > > const addr_t func_end_file_addr = func_start_file_addr + > > m_range.GetByteSize(); > > + > > + // Now calculate the offset to pass the subsequent line 0 > > entries. > > + uint32_t first_non_zero_line = prologue_end_line_idx; > > + while (1) > > + { > > + LineEntry line_entry; > > + if > > (line_table->GetLineEntryAtIndex(first_non_zero_line, line_entry)) > > + { > > + if (line_entry.line != 0) > > + break; > > + } > > + if (line_entry.range.GetBaseAddress().GetFileAddress() > > >= func_end_file_addr) > > + break; > > + > > + first_non_zero_line++; > > + } > > + > > + if (first_non_zero_line > prologue_end_line_idx) > > + { > > + LineEntry first_non_zero_entry; > > + if > > (line_table->GetLineEntryAtIndex(first_non_zero_line, first_non_zero_entry)) > > + { > > + line_zero_end_file_addr = > > first_non_zero_entry.range.GetBaseAddress().GetFileAddress(); > > + } > > + } > > > > // Verify that this prologue end file address in the > > function's > > // address range just to be sure > > @@ -635,10 +669,16 @@ Function::GetPrologueByteSize () > > { > > m_prologue_byte_size = prologue_end_file_addr - > > func_start_file_addr; > > } > > + > > + if (prologue_end_file_addr < line_zero_end_file_addr && > > line_zero_end_file_addr < func_end_file_addr) > > + { > > + m_prologue_byte_size += line_zero_end_file_addr - > > prologue_end_file_addr; > > + } > > } > > } > > } > > - return m_prologue_byte_size; > > + > > + return m_prologue_byte_size; > > } > > > > lldb::LanguageType > > > > > > _______________________________________________ > > lldb-commits mailing list > > lldb-commits@lists.llvm.org <mailto:lldb-commits@lists.llvm.org> > > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits > > <http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits> >
_______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
