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Minor copy edits. 

llvm-svn: 113674
This commit is contained in:
Jason Molenda 2010-09-11 00:37:21 +00:00
parent 4550154d31
commit 8f22a243b7
1 changed files with 60 additions and 64 deletions
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124
lldb/docs/lldb-for-gdb-users.txt
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@ -50,7 +50,8 @@ So you say:
(lldb) breakpoint set -f foo.c -l 12
to set a file & line breakpoint. To set a breakpoint on a function by name, you do:
to set a file & line breakpoint. To set a breakpoint on a function
by name, you do:
(lldb) breakpoint set -n foo
@ -58,7 +59,7 @@ This can allow us to be more expressive, so you can say:
(lldb) breakpoint set -M foo
to break on all methods named foo, or:
to break on all C++ methods named foo, or:
(lldb) breakpoint set -S alignLeftEdges:
@ -82,14 +83,14 @@ typed:
lldb also supports command completion for source file names, symbol
names, file names, etc. Completion is initiated by a hitting a <TAB>.
Individual options a command can have different completers, so for
Individual options in a command can have different completers, so for
instance the -f option in "breakpoint" completes to source files, the
-s option to currently loaded dylibs, etc... We can even do things
like if you specify -s, and are completing on -f, we will only
list source files in the dylib specified by -s...
-s option to currently loaded shared libraries, etc... We can even do
things like if you specify -s, and are completing on -f, we will only
list source files in the shared library specified by -s...
The individual commands are pretty extensively documented, using
with the "help" command. And there is an "apropos" command that will
the "help" command. And there is an "apropos" command that will
search the help for a particular word and dump a summary help string
for each matching command.
@ -158,51 +159,53 @@ You can find out about the breakpoints you've set with:
(lldb) break list
Current breakpoints:
1: name = 'alignLeftEdges:', locations = 1, resolved = 1
1.1: where = Sketch`-[SKTGraphicView alignLeftEdges:] + 33 at /Volumes/ThePlayground/Users/jingham/Projects/Sketch/SKTGraphicView.m:1405, address = 0x0000000100010d5b, resolved, hit count = 0
1.1: where = Sketch`-[SKTGraphicView alignLeftEdges:] + 33 at /Projects/Sketch/SKTGraphicView.m:1405, address = 0x0000000100010d5b, resolved, hit count = 0
Note that each "logical" breakpoint can have multiple "locations".
The logical breakpoint has an integer id, and it's locations have a an
The logical breakpoint has an integer id, and it's locations have an
id within their parent breakpoint (the two are joined by a ".",
e.g. 1.1 in the example above.)
Also the breakpoints remain "live" so that if another shared library
were to be loaded that had another implementation of the
"alignLeftEdges:" selector, and new location would be added to the
breakpoint 1 for it.
"alignLeftEdges:" selector, the new location would be added to
breakpoint 1 (e.g. a "1.2" breakpoint would be set on the newly loaded
selector).
The other piece of information in the breakpoint listing is whether the
breakpoint location was "resolved" or not. A location gets resolved when
the file address it corresponds to gets loaded into the program you are
debugging. For instance if you set a breakpoint in a dylib that then
gets unloaded, that breakpoint location will remain, but it will no longer
be "resolved".
debugging. For instance if you set a breakpoint in a shared library that
then gets unloaded, that breakpoint location will remain, but it will no
longer be "resolved".
One other thing to note for gdb users is that lldb acts like gdb with:
(gdb) set breakpoint pending on
That is, lldb always make breakpoints from your specification, even if it
couldn't find any locations that match the specification. You can tell whether the
expression was resolved or not by checking the locations field in the breakpoint
reporting, and we mark the breakpoint as "pending" so you can tell you've made
a typo more easily, if that was indeed the reason no locations were found:
That is, lldb should always make a breakpoint from your specification, even
if it couldn't find any locations that match the specification. You can tell
whether the expression was resolved or not by checking the locations field
in "breakpoint list", and we report the breakpoint as "pending" when you
set it so you can tell you've made a typo more easily, if that was indeed
the reason no locations were found:
(lldb) b s -f no_such_file.c -l 10000000
Breakpoint created: 1: file ='no_such_file.c', line = 10000000, locations = 0 (pending)
You can delete, disable, set conditions and ignore counts either on
all the locations generated by your logical breakpoint. So for
instance if we wanted to add a command to print a backtrace when we
hit this breakpoint we could do:
You can delete, disable, set conditions and ignore counts either on all the
locations generated by your logical breakpoint, or on particular locations
your specification resolved to. For instance if we wanted to add a command
to print a backtrace when we hit this breakpoint we could do:
(lldb) b command add -c 1.1
Enter your debugger command(s). Type 'DONE' to end.
> bt
> DONE
The "-c" specifies that the breakpoint command is a set of lldb
The "-c" option specifies that the breakpoint command is a set of lldb
commmand interpreter commands. Use "-s" if you want to implement your
breakpoint command using the lldb Python interface instead.
breakpoint command using the Python interface instead.
c) Running the program:
@ -240,7 +243,7 @@ listed in the stop message.
d) Controlling execution:
Then we can continue till we hit our breakpoint. The primitive
After launching, we can continue until we hit our breakpoint. The primitive
commands for process control all exist under the "thread" command:
(lldb) thread continue
@ -250,31 +253,23 @@ Resuming process 46915
At present you can only operate on one thread at a time, but the
design will ultimately support saying "step over the function in
Thread-1, and step into the function in Thread 2, and continue Thread
Thread 1, and step into the function in Thread 2, and continue Thread
3" etc. When we eventually support keeping some threads running while
others are stopped this will be particularly important. For
convenience, however, all the stepping type commands have easy
aliases. So "thread continue" is just "c", etc.
convenience, however, all the stepping commands have easy aliases.
So "thread continue" is just "c", etc.
The other program stepping commands are pretty much the same as in gdb. You've got:
The other program stepping commands are pretty much the same as in gdb.
You've got:
(lldb) thread step-in
1. (lldb) thread step-in
The same as gdb's "step" -- there is also the alias "s" in lldb
which is the same as gdb's "step" or the alias:
2. (lldb) thread step-over
The same as gdb's "next" -- there is also the alias "n" in lldb
(lldb) s
(lldb) thread step-over
which is the same as gdb's "next" and is aliased to
(lldb) n
(lldb) thread step-out
which is the same as gdb's "finish" and is aliased to
(lldb) f
3. (lldb) thread step-out
The same as gdb's "finish" -- there is also the alias "f" in lldb
And the "by instruction" versions:
@ -287,17 +282,16 @@ Finally, there's:
which runs the thread in the current frame till it reaches line 100 in
this frame or stops if it leaves the current frame. This is a pretty
close equivalent to gdb's until command.
close equivalent to gdb's "until" command.
One thing here that might be a little disconcerting to gdb users here
is that when you resume you immediately get a prompt back. That's
because the lldb interpreter remains live when you are running the
target. This allows you to set a breakpoint, etc without having to
explicitly interrupt the program you are debugging. We're still
working out all the operations that it is safe to do while running.
But this way of operation will set us up for "no stop" debugging when
we get to implementing that.
One thing here that might be a little disconcerting to gdb users here is that
when you resume process execution, you immediately get a prompt back. That's
because the lldb interpreter remains live when you are running the target.
This allows you to set a breakpoint, etc without having to explicitly interrupt
the program you are debugging. We're still working out all the operations
that it is safe to do while running. But this way of operation will set us
up for "no stop" debugging when we get to implementing that.
If you want to interrupt a running program do:
@ -353,7 +347,7 @@ thread #1: tid = 0x2c03, stop reason = breakpoint 1.1, queue = com.apple.main-th
You can also provide a list of threads to backtrace, or the keyword
"all" to see all threads:
(lldb) thread backtrace all...
(lldb) thread backtrace all
Next task is inspecting data:
@ -372,7 +366,8 @@ You can also choose particular variables to view:
(lldb) frame variable self
(SKTGraphicView *) self = 0x0000000100208b40
The frame variable command is not a full expression parser but it does support some common operations like defererencing:
The frame variable command is not a full expression parser but it
does support some common operations like defererencing:
(lldb) fr v *self
(SKTGraphicView *) self = 0x0000000100208b40
@ -382,11 +377,11 @@ The frame variable command is not a full expression parser but it does support s
and structure element references:
(lldb) frame variable self.NS(lldb) frame variable self.isa
(lldb) frame variable self.isa
(struct objc_class *) self.isa = 0x0000000100023730
The frame variable command will also perform "object printing" operations on variables (currently we
only support NSPrintForDebugger) with:
The frame variable command will also perform "object printing" operations on
variables (currently we only support NSPrintForDebugger) with:
(lldb) fr v -o self
(SKTGraphicView *) self = 0x0000000100208b40
@ -426,12 +421,13 @@ You can also call functions:
$2 = (int) 22
I have a pointer 0x0.
One thing to note from this example is that lldb commands can be
defined to take "raw" input. "expression" is one of these. So in the expression command,
you don't have to quote your whole expression, nor backslash protect quotes, etc...
One thing to note from this example is that lldb commands can be defined to
take "raw" input. "expression" is one of these. So in the expression command,
you don't have to quote your whole expression, nor backslash protect quotes,
etc...
Finally, the results of the expressions are stored in persistent
variables (of the form \$([0-9])+) that you can use in further expressions, like:
Finally, the results of the expressions are stored in persistent variables
(of the form $[0-9]+) that you can use in further expressions, like:
(lldb) expr self = $0
$4 = (SKTGraphicView *) 0x0000000100135430