Re: [Tarantool-patches] [PATCH luajit 1/2] test: add utility for parsing `jit.dump`

[Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi, Maxim!
Thanks for the review!
Please consider my answers below.

On 15.05.23, Maxim Kokryashkin wrote:
> 
> Hi, Sergey!
> Thanks for the patch!
> Please consider my comments below.
>  
> > 
> >>This commit adds simple parser for traces to be analyzed in the test.
> >Typo: s/adds/adds a/

Fixed.

> >>For now nothing too fancy at all -- just start `jit.dump` to temporary
> >Typo: s/temporary/a temporary/

Fixed.

> >>file and parse and remove this file when dump is stopped. The array
> >>with resulting traces is returned.
> >>
> >>For now, just find a single IR by pattern and return ref number and IR,
> >>if exists. More functionality may be added if it will be necessary for
> >Typo: s/if exists/if they exist/
> >Typo: s/it will be/it is/

Fixed, thanks!

> >>tests.
> >>---
> >> test/tarantool-tests/utils/jit_parse.lua | 156 +++++++++++++++++++++++
> >> 1 file changed, 156 insertions(+)
> >> create mode 100644 test/tarantool-tests/utils/jit_parse.lua
> >>
> >>diff --git a/test/tarantool-tests/utils/jit_parse.lua b/test/tarantool-tests/utils/jit_parse.lua
> >>new file mode 100644
> >>index 00000000..fe8e0e08
> >>--- /dev/null
> >>+++ b/test/tarantool-tests/utils/jit_parse.lua
> >>@@ -0,0 +1,156 @@

<snipped>

> >>+local function parse_trace_hdr(ctx, line, trace_num, status)
> >>+ local traces = ctx.traces
> >>+ if status == 'start' then
> >>+ local trace = trace_new(trace_num)
> >>+ trace.parent, trace.parent_exitno = line:match('start (%d+)/(%d+)')
> >>+ -- XXX: Assume, that source line can't contain spaces.
> >>+ -- For example, it's not "(command line)".
> >>+ trace.start_loc = line:match(' ([^%s]+)$')
> >>+ traces[trace_num] = trace
> >>+ ctx.parsing_trace = trace_num
> >>+ ctx.parsing = 'bc'
> >>+ elseif status == 'stop' then
> >>+ assert(ctx.parsing_trace == trace_num)
> >>+ ctx.parsing_trace = nil
> >>+ ctx.parsing = nil
> >>+ elseif status == 'abort' then
> >>+ assert(ctx.parsing_trace == trace_num)
> >>+ ctx.parsing_trace = nil
> >>+ ctx.parsing = nil
> >>+ traces[trace_num] = nil
> >Two branches below are almost identical. Is it possible to avoid
> >duplication?

I suppose, no, especially since we may want to do some more work for
aborted traces (I just don't sure for now).

> >Side note: Also, I like it much more when switch-like constructions
> >in Lua are implemented with tables, because it seems to be cleaner.
> >Feel free to ignore.

Rewritten in this way, see the iterative patch below. Branch is
force-pushed.

===================================================================
diff --git a/test/tarantool-tests/utils/jit_parse.lua b/test/tarantool-tests/utils/jit_parse.lua
index fe8e0e08..7e8f879e 100644
--- a/test/tarantool-tests/utils/jit_parse.lua
+++ b/test/tarantool-tests/utils/jit_parse.lua
@@ -64,9 +64,9 @@ local function parse_mcode(trace, line)
   trace.mcode[#trace.mcode + 1] = {addr = addr, instruction = instruction,}
 end
 
-local function parse_trace_hdr(ctx, line, trace_num, status)
-  local traces = ctx.traces
-  if status == 'start' then
+local header_handlers = {
+  start = function(ctx, line, trace_num)
+    local traces = ctx.traces
     local trace = trace_new(trace_num)
     trace.parent, trace.parent_exitno = line:match('start (%d+)/(%d+)')
     -- XXX: Assume, that source line can't contain spaces.
@@ -75,23 +75,27 @@ local function parse_trace_hdr(ctx, line, trace_num, status)
     traces[trace_num] = trace
     ctx.parsing_trace = trace_num
     ctx.parsing = 'bc'
-  elseif status == 'stop' then
+  end,
+  stop = function(ctx, line, trace_num)
+    local traces = ctx.traces
     assert(ctx.parsing_trace == trace_num)
     ctx.parsing_trace = nil
     ctx.parsing = nil
-  elseif status == 'abort' then
+  end,
+  abort = function(ctx, line, trace_num)
+    local traces = ctx.traces
     assert(ctx.parsing_trace == trace_num)
     ctx.parsing_trace = nil
     ctx.parsing = nil
     traces[trace_num] = nil
-  elseif status == 'IR' then
+  end,
+  IR = function(ctx, line, trace_num)
     ctx.parsing = 'IR'
-  elseif status == 'mcode' then
+  end,
+  mcode = function(ctx, line, trace_num)
     ctx.parsing = 'mcode'
-  else
-    error('Unknown trace status: ' .. status)
-  end
-end
+  end,
+}
 
 local function parse_line(ctx, line)
   if line == '' then
@@ -105,7 +109,11 @@ local function parse_line(ctx, line)
 
   local trace_num, status = line:match('TRACE (%d+) (%w+)')
   if trace_num then
-    parse_trace_hdr(ctx, line, tonumber(trace_num), status)
+    if (header_handlers[status]) then
+       header_handlers[status](ctx, line, tonumber(trace_num))
+    else
+      error('Unknown trace status: ' .. status)
+    end
     return
   end
===================================================================

> >>+ elseif status == 'IR' then
> >>+ ctx.parsing = 'IR'
> >>+ elseif status == 'mcode' then
> >>+ ctx.parsing = 'mcode'
> >>+ else
> >>+ error('Unknown trace status: ' .. status)
> >>+ end
> >>+end
> >>+

<snipped>

> >>+
> >>+local JDUMP_FILE
> >>+
> >>+local function parse_jit_dump()
> >>+ local ctx = {traces = {}}
> >>+ for line in io.lines(JDUMP_FILE) do
> >I think we should perform error checking for that io operation.

It is done under the hood:
| $ src/luajit -e 'for _ in io.lines("unexisted") do end '
| src/luajit: (command line):1: bad argument #1 to 'lines' (unexisted: No such file or directory)
| stack traceback:
|         [C]: in function 'lines'
|         (command line):1: in main chunk
|         [C]: at 0x55b73c281064

> >>+ parse_line(ctx, line)
> >>+ end
> >>+ return ctx.traces
> >>+end
> >>+
> >>+M.start = function(flags)
> >>+ assert(JDUMP_FILE == nil, 'jit_parse is already running')
> >>+ -- Always use plain text output.
> >>+ flags = flags .. 'T'
> >Nit: What if either `A` or `H` is present in the flags? I believe, no
> >one is going to do such things, but anyway it is worth considering
> >as a thing to check. Feel free to ignore.

It is rewritten by the last flag (i.e. appended `T`).

> >>+ JDUMP_FILE = os.tmpname()
> >>+ jdump.start(flags, JDUMP_FILE)
> >>+end
> >>+
> >>+M.finish = function()
> >>+ assert(JDUMP_FILE ~= nil, 'jit_parse is not running')
> >>+ jdump.off()
> >>+ local traces = parse_jit_dump()
> >>+ os.remove(JDUMP_FILE)
> >>+ JDUMP_FILE = nil
> >>+ return traces
> >>+end
> >>+
> >>+-- Turn off compilation for these modules to avoid side effects.
> >>+jit.off(true, true)
> >>+jit.off(jdump.on, true)
> >>+jit.off(jdump.off, true)
> >>+
> >>+return M
> >>--
> >>2.34.1
> >--
> >Best regards,
> >Maxim Kokryashkin
> > 

-- 
Best regards,
Sergey Kaplun