The TestBreakpointCommand test is incorrectly disabled for Windows
target. We can disable it for Windows host instead or just fix the
issue. This patch fixes the path separator in
BreakpointResolverFileLine::DeduceSourceMapping() and the Windows
specific absolute path in the test in case of the Windows host.
Adds a `show_function_display_name` parameter to
`SymbolContext::DumpStopContext`. This
parameter defaults to false, but `BreakpointLocation::GetDescription`
sets it to true.
This is NFC in mainline lldb, and will be used to modify how Swift
breakpoint locations are printed.
that separates out language and version. To avoid reinventing the wheel
and introducing subtle incompatibilities, this API uses the table of
languages and versiond defined by the upcoming DWARF 6 standard
(https://dwarfstd.org/languages-v6.html). While the DWARF 6 spec is not
finialized, the list of languages is broadly considered stable.
The primary motivation for this is to allow the Swift language plugin to
switch between language dialects between, e.g., Swift 5.9 and 6.0 with
out introducing a ton of new language codes. On the main branch this
change is considered NFC.
Depends on https://github.com/llvm/llvm-project/pull/89980
We check if the next character after `N.` is `*` before we check its
length. Using `split` on the string is cleaner and less error prone than
using indices with `find` and `substr`.
Note: this does not make `N.` mean anything, it just prevents assertion
failures. `N.` is treated the same as an unrecognized breakpoint name:
```
(lldb) breakpoint enable 1
1 breakpoints enabled.
(lldb) breakpoint enable 1.*
1 breakpoints enabled.
(lldb) breakpoint enable 1.
0 breakpoints enabled.
(lldb) breakpoint enable xyz
0 breakpoints enabled.
```
Found via LLDB fuzzers.
This is another step towards supporting DWARF5 checksums and inline
source code in LLDB. This is a reland of #85468 but without the
functional change of storing the support file from the line table (yet).
Some languages may create artificial functions that have no real user
code, even though there is line table information for them. One such
case is with coroutine code that receives the CoroSplitter
transformation in LLVM IR. That code transformation creates many
different Functions, cloning one Instruction into many Instructions in
many different Functions and copying the associated debug locations.
It would be difficult to make that pass delete debug locations of cloned
instructions in a language agnostic way (is it even possible?), but LLDB
can ignore certain locations by querying its Language APIs and having it
decide based on, for example, mangling information.
When debugging LLDB itself, it can often be useful to know the mangled
name of the function where a breakpoint is set. Since the `--verbose`
setting of `break --list` is aimed at debugging LLDB, this patch makes
it so that the mangled name is also printed in that mode.
Note about testing: since mangling is not the same on Windows and Linux,
the test refrains from hardcoding mangled names.
debugserver on arm64 devices can manage both Byte Address Select
watchpoints (1-8 bytes) and MASK watchpoints (8 bytes-2 gigabytes). This
adds a SupportedWatchpointTypes key to the QSupported response from
debugserver with a list of these, so lldb can take full advantage of
them when creating larger regions with a single hardware watchpoint.
Also add documentation for this, and two other lldb extensions, to the
lldb-gdb-remote.txt documentation.
Re-enable TestLargeWatchpoint.py on Darwin systems when testing with the
in-tree built debugserver. I can remove the "in-tree built debugserver"
in the future when this new key is handled by an Xcode debugserver.
This patch is the next piece of work in my Large Watchpoint proposal,
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
This patch breaks a user's watchpoint into one or more
WatchpointResources which reflect what the hardware registers can cover.
This means we can watch objects larger than 8 bytes, and we can watched
unaligned address ranges. On a typical 64-bit target with 4 watchpoint
registers you can watch 32 bytes of memory if the start address is
doubleword aligned.
Additionally, if the remote stub implements AArch64 MASK style
watchpoints (e.g. debugserver on Darwin), we can watch any power-of-2
size region of memory up to 2GB, aligned to that same size.
I updated the Watchpoint constructor and CommandObjectWatchpoint to
create a CompilerType of Array<UInt8> when the size of the watched
region is greater than pointer-size and we don't have a variable type to
use. For pointer-size and smaller, we can display the watched granule as
an integer value; for larger-than-pointer-size we will display as an
array of bytes.
I have `watchpoint list` now print the WatchpointResources used to
implement the watchpoint.
I added a WatchpointAlgorithm class which has a top-level static method
that takes an enum flag mask WatchpointHardwareFeature and a user
address and size, and returns a vector of WatchpointResources covering
the request. It does not take into account the number of watchpoint
registers the target has, or the number still available for use. Right
now there is only one algorithm, which monitors power-of-2 regions of
memory. For up to pointer-size, this is what Intel hardware supports.
AArch64 Byte Address Select watchpoints can watch any number of
contiguous bytes in a pointer-size memory granule, that is not currently
supported so if you ask to watch bytes 3-5, the algorithm will watch the
entire doubleword (8 bytes). The newly default "modify" style means we
will silently ignore modifications to bytes outside the watched range.
I've temporarily skipped TestLargeWatchpoint.py for all targets. It was
only run on Darwin when using the in-tree debugserver, which was a proxy
for "debugserver supports MASK watchpoints". I'll be adding the
aforementioned feature flag from the stub and enabling full mask
watchpoints when a debugserver with that feature is enabled, and
re-enable this test.
I added a new TestUnalignedLargeWatchpoint.py which only has one test
but it's a great one, watching a 22-byte range that is unaligned and
requires four 8-byte watchpoints to cover.
I also added a unit test, WatchpointAlgorithmsTests, which has a number
of simple tests against WatchpointAlgorithms::PowerOf2Watchpoints. I
think there's interesting possible different approaches to how we cover
these; I note in the unit test that a user requesting a watch on address
0x12e0 of 120 bytes will be covered by two watchpoints today, a
128-bytes at 0x1280 and at 0x1300. But it could be done with a 16-byte
watchpoint at 0x12e0 and a 128-byte at 0x1300, which would have fewer
false positives/private stops. As we try refining this one, it's helpful
to have a collection of tests to make sure things don't regress.
I tested this on arm64 macOS, (genuine) x86_64 macOS, and AArch64
Ubuntu. I have not modifed the Windows process plugins yet, I might try
that as a standalone patch, I'd be making the change blind, but the
necessary changes (see ProcessGDBRemote::EnableWatchpoint) are pretty
small so it might be obvious enough that I can change it and see what
the Windows CI thinks.
There isn't yet a packet (or a qSupported feature query) for the gdb
remote serial protocol stub to communicate its watchpoint capabilities
to lldb. I'll be doing that in a patch right after this is landed,
having debugserver advertise its capability of AArch64 MASK watchpoints,
and have ProcessGDBRemote add eWatchpointHardwareArmMASK to
WatchpointAlgorithms so we can watch larger than 32-byte requests on
Darwin.
I haven't yet tackled WatchpointResource *sharing* by multiple
Watchpoints. This is all part of the goal, especially when we may be
watching a larger memory range than the user requested, if they then add
another watchpoint next to their first request, it may be covered by the
same WatchpointResource (hardware watchpoint register). Also one "read"
watchpoint and one "write" watchpoint on the same memory granule need to
be handled, making the WatchpointResource cover all requests.
As WatchpointResources aren't shared among multiple Watchpoints yet,
there's no handling of running the conditions/commands/etc on multiple
Watchpoints when their shared WatchpointResource is hit. The goal beyond
"large watchpoint" is to unify (much more) the Watchpoint and Breakpoint
behavior and commands. I have a feeling I may be slowly chipping away at
this for a while.
Re-landing this patch after fixing two undefined behaviors in
WatchpointAlgorithms found by UBSan and by failures on different
CI bots.
rdar://108234227
The purpose of m_being_created in these classes was to prevent
broadcasting an event related to these Breakpoints during the creation
of the breakpoint (i.e. in the constructor). In Breakpoint and
Watchpoint, m_being_created had no effect. That is to say, removing it
does not change behavior.
However, BreakpointLocation does still use m_being_created. In the
constructor, SetThreadID is called which does broadcast an event only if
`m_being_created` is false. Instead of having this logic be roundabout,
the constructor instead calls `SetThreadIDInternal`, which actually
changes the thread ID. `SetThreadID` also will call
`SetThreadIDInternal` in addition to broadcasting a changed event.
This patch is the next piece of work in my Large Watchpoint proposal,
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
This patch breaks a user's watchpoint into one or more
WatchpointResources which reflect what the hardware registers can cover.
This means we can watch objects larger than 8 bytes, and we can watched
unaligned address ranges. On a typical 64-bit target with 4 watchpoint
registers you can watch 32 bytes of memory if the start address is
doubleword aligned.
Additionally, if the remote stub implements AArch64 MASK style
watchpoints (e.g. debugserver on Darwin), we can watch any power-of-2
size region of memory up to 2GB, aligned to that same size.
I updated the Watchpoint constructor and CommandObjectWatchpoint to
create a CompilerType of Array<UInt8> when the size of the watched
region is greater than pointer-size and we don't have a variable type to
use. For pointer-size and smaller, we can display the watched granule as
an integer value; for larger-than-pointer-size we will display as an
array of bytes.
I have `watchpoint list` now print the WatchpointResources used to
implement the watchpoint.
I added a WatchpointAlgorithm class which has a top-level static method
that takes an enum flag mask WatchpointHardwareFeature and a user
address and size, and returns a vector of WatchpointResources covering
the request. It does not take into account the number of watchpoint
registers the target has, or the number still available for use. Right
now there is only one algorithm, which monitors power-of-2 regions of
memory. For up to pointer-size, this is what Intel hardware supports.
AArch64 Byte Address Select watchpoints can watch any number of
contiguous bytes in a pointer-size memory granule, that is not currently
supported so if you ask to watch bytes 3-5, the algorithm will watch the
entire doubleword (8 bytes). The newly default "modify" style means we
will silently ignore modifications to bytes outside the watched range.
I've temporarily skipped TestLargeWatchpoint.py for all targets. It was
only run on Darwin when using the in-tree debugserver, which was a proxy
for "debugserver supports MASK watchpoints". I'll be adding the
aforementioned feature flag from the stub and enabling full mask
watchpoints when a debugserver with that feature is enabled, and
re-enable this test.
I added a new TestUnalignedLargeWatchpoint.py which only has one test
but it's a great one, watching a 22-byte range that is unaligned and
requires four 8-byte watchpoints to cover.
I also added a unit test, WatchpointAlgorithmsTests, which has a number
of simple tests against WatchpointAlgorithms::PowerOf2Watchpoints. I
think there's interesting possible different approaches to how we cover
these; I note in the unit test that a user requesting a watch on address
0x12e0 of 120 bytes will be covered by two watchpoints today, a
128-bytes at 0x1280 and at 0x1300. But it could be done with a 16-byte
watchpoint at 0x12e0 and a 128-byte at 0x1300, which would have fewer
false positives/private stops. As we try refining this one, it's helpful
to have a collection of tests to make sure things don't regress.
I tested this on arm64 macOS, (genuine) x86_64 macOS, and AArch64
Ubuntu. I have not modifed the Windows process plugins yet, I might try
that as a standalone patch, I'd be making the change blind, but the
necessary changes (see ProcessGDBRemote::EnableWatchpoint) are pretty
small so it might be obvious enough that I can change it and see what
the Windows CI thinks.
There isn't yet a packet (or a qSupported feature query) for the gdb
remote serial protocol stub to communicate its watchpoint capabilities
to lldb. I'll be doing that in a patch right after this is landed,
having debugserver advertise its capability of AArch64 MASK watchpoints,
and have ProcessGDBRemote add eWatchpointHardwareArmMASK to
WatchpointAlgorithms so we can watch larger than 32-byte requests on
Darwin.
I haven't yet tackled WatchpointResource *sharing* by multiple
Watchpoints. This is all part of the goal, especially when we may be
watching a larger memory range than the user requested, if they then add
another watchpoint next to their first request, it may be covered by the
same WatchpointResource (hardware watchpoint register). Also one "read"
watchpoint and one "write" watchpoint on the same memory granule need to
be handled, making the WatchpointResource cover all requests.
As WatchpointResources aren't shared among multiple Watchpoints yet,
there's no handling of running the conditions/commands/etc on multiple
Watchpoints when their shared WatchpointResource is hit. The goal beyond
"large watchpoint" is to unify (much more) the Watchpoint and Breakpoint
behavior and commands. I have a feeling I may be slowly chipping away at
this for a while.
rdar://108234227
`FindBreakpointID` take a BreakpointID and a pointer to a size_t (so you
can get position information). It returns a bool to indicate whether the
id was found in the list or not.
There are 2 callers of this currently and neither one actually uses the
position information, so I removed it. After that, I renamed it to
Contains to more accurately reflect the intent. Additionally, I changed
the argument type from a reference to a value (because BreakpointID is
just a wrapper around 2 integers, copies are cheap).
I originally thought to try to guesstimate the hardware watchpoint index
number that a Resource was associated with, but gdb remote serial
protocol doesn't give us the hardware register index used so it was only
a guess. I changed my mind and simply use ever-incrementing ID numbers
for the WatchpointResources, but forgot to remove the SetID method.
In `[lldb] [mostly NFC] Large WP foundation: WatchpointResources
(#68845)` I added a new template StopPointSiteList to combine
WatchpointResourceList and BreakpointSiteList. But I didn't remove the
now-unused WatchpointResourceList class. This patch fixes that.
BroadcastEvent currently takes its EventData* param and shoves it into
an Event object, which takes ownership of the pointer and places it into
a shared_ptr to manage the lifetime.
Instead of relying on `new` and passing raw pointers around, I think it
would make more sense to create the shared_ptr up front.
The lifetime of these BreakpointEventData objects is difficult to reason
about. These BreakpointEventData pointers are created and passed along
to `Event` which takes the raw pointer and sticks them in a shared
pointer. Instead of manually managing the lifetime and memory, it would
be simpler to have them be shared pointers from the start.
Store a SupportFile, rather than a FileSpec, in LineEntry. This commit
works towards having the SourceManageroperate on SupportFiles so that it
can (1) validate the Checksum and (2) materialize the content of inline
source information.
BreakpointIDList does not need to know about CommandReturnObject.
BreakpointIDList::FindAndReplaceIDRanges is the last place that uses it
in BreakpointIDList.
Instead of passing in a CommandReturnObject, it now returns an
llvm::Error. The callsite uses the Error to populate the
CommandReturnObject as needed.
There are 2 motivations here:
1.) There is no need to hand out constant references to BreakpointIDs,
they are only 8 bytes big. In addition, every use of this method already
makes a copy anyway.
2.) Each BreakpointIDList held onto an invalid BreakpointID specifically
to
prevent lifetime issues. Returning a value means you can return an
invalid BreakpointID instead of needing to allocate storage for an
invalid BreakpointID.
This abstraction is leaky and BreakpointIDList does not need to know
about CommandReturnObject.
Additionally, setting the CommandReturnObject inout param to a success
state does very little. The function returns immediately if the input
ArrayRef is empty, and reading
CommandObjectMultiwordBreakpoint::VerifyIDs more closely, the input is
always empty if the previous call to
BreakpointIDList::FindAndReplaceIDRanges failed. If the call was
successful, then the CommandReturnObject is already in a success state.
I have opted to remove the function altogether and inline the
functionality where it was used.
BreakpointResolverAddress optionally can include the module name related
to the address that gets resolved. Currently this will never work
because it sets the name to itself (which is empty).
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
Tries to fix:
../../lldb/source/Breakpoint/WatchpointResource.cpp:59:12:
error: no member named 'find' in namespace 'std'; did you mean 'fill'?
std::find(m_constituents.begin(), m_constituents.end(), wp_sp);
~~~~~^~~~
fill
(cherry picked from commit a6c62bf1a4)
This patch is rearranging code a bit to add WatchpointResources to
Process. A WatchpointResource is meant to represent a hardware
watchpoint register in the inferior process. It has an address, a size,
a type, and a list of Watchpoints that are using this
WatchpointResource.
This current patch doesn't add any of the features of
WatchpointResources that make them interesting -- a user asking to watch
a 24 byte object could watch this with three 8 byte WatchpointResources.
Or a Watchpoint on 1 byte at 0x1002 and a second watchpoint on 1 byte at
0x1003, these must both be served by a single WatchpointResource on that
doubleword at 0x1000 on a 64-bit target, if two hardware watchpoint
registers were used to track these separately, one of them may not be
hit. Or if you have one Watchpoint on a variable with a condition set,
and another Watchpoint on that same variable with a command defined or
different condition, or ignorecount, both of those Watchpoints need to
evaluate their criteria/commands when their WatchpointResource has been
hit.
There's a bit of code movement to rearrange things in the direction I'll
need for implementing this feature, so I want to start with reviewing &
landing this mostly NFC patch and we can focus on the algorithmic
choices about how WatchpointResources are shared and handled as they're
triggeed, separately.
This patch also stops printing "Watchpoint <n> hit: old value: <x>, new
vlaue: <y>" for Read watchpoints. I could make an argument for print
"Watchpoint <n> hit: current value <x>" but the current output doesn't
make any sense, and the user can print the value if they are
particularly interested. Read watchpoints are used primarily to
understand what code is reading a variable.
This patch adds more fallbacks for how to print the objects being
watched if we have types, instead of assuming they are all integral
values, so a struct will print its elements. As large watchpoints are
added, we'll be doing a lot more of those.
To track the WatchpointSP in the WatchpointResources, I changed the
internal API which took a WatchpointSP and devolved it to a Watchpoint*,
which meant touching several different Process files. I removed the
watchpoint code in ProcessKDP which only reported that watchpoints
aren't supported, the base class does that already.
I haven't yet changed how we receive a watchpoint to identify the
WatchpointResource responsible for the trigger, and identify all
Watchpoints that are using this Resource to evaluate their conditions
etc. This is the same work that a BreakpointSite needs to do when it has
been tiggered, where multiple Breakpoints may be at the same address.
There is not yet any printing of the Resources that a Watchpoint is
implemented in terms of ("watchpoint list", or
SBWatchpoint::GetDescription).
"watchpoint set var" and "watchpoint set expression" take a size
argument which was previously 1, 2, 4, or 8 (an enum). I've changed this
to an unsigned int. Most hardware implementations can only watch 1, 2,
4, 8 byte ranges, but with Resources we'll allow a user to ask for
different sized watchpoints and set them in hardware-expressble terms
soon.
I've annotated areas where I know there is work still needed with
LWP_TODO that I'll be working on once this is landed.
I've tested this on aarch64 macOS, aarch64 Linux, and Intel macOS.
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
(cherry picked from commit fc6b72523f)
Tries to fix:
../../lldb/source/Breakpoint/WatchpointResource.cpp:59:12:
error: no member named 'find' in namespace 'std'; did you mean 'fill'?
std::find(m_constituents.begin(), m_constituents.end(), wp_sp);
~~~~~^~~~
fill
This patch is rearranging code a bit to add WatchpointResources to
Process. A WatchpointResource is meant to represent a hardware
watchpoint register in the inferior process. It has an address, a size,
a type, and a list of Watchpoints that are using this
WatchpointResource.
This current patch doesn't add any of the features of
WatchpointResources that make them interesting -- a user asking to watch
a 24 byte object could watch this with three 8 byte WatchpointResources.
Or a Watchpoint on 1 byte at 0x1002 and a second watchpoint on 1 byte at
0x1003, these must both be served by a single WatchpointResource on that
doubleword at 0x1000 on a 64-bit target, if two hardware watchpoint
registers were used to track these separately, one of them may not be
hit. Or if you have one Watchpoint on a variable with a condition set,
and another Watchpoint on that same variable with a command defined or
different condition, or ignorecount, both of those Watchpoints need to
evaluate their criteria/commands when their WatchpointResource has been
hit.
There's a bit of code movement to rearrange things in the direction I'll
need for implementing this feature, so I want to start with reviewing &
landing this mostly NFC patch and we can focus on the algorithmic
choices about how WatchpointResources are shared and handled as they're
triggeed, separately.
This patch also stops printing "Watchpoint <n> hit: old value: <x>, new
vlaue: <y>" for Read watchpoints. I could make an argument for print
"Watchpoint <n> hit: current value <x>" but the current output doesn't
make any sense, and the user can print the value if they are
particularly interested. Read watchpoints are used primarily to
understand what code is reading a variable.
This patch adds more fallbacks for how to print the objects being
watched if we have types, instead of assuming they are all integral
values, so a struct will print its elements. As large watchpoints are
added, we'll be doing a lot more of those.
To track the WatchpointSP in the WatchpointResources, I changed the
internal API which took a WatchpointSP and devolved it to a Watchpoint*,
which meant touching several different Process files. I removed the
watchpoint code in ProcessKDP which only reported that watchpoints
aren't supported, the base class does that already.
I haven't yet changed how we receive a watchpoint to identify the
WatchpointResource responsible for the trigger, and identify all
Watchpoints that are using this Resource to evaluate their conditions
etc. This is the same work that a BreakpointSite needs to do when it has
been tiggered, where multiple Breakpoints may be at the same address.
There is not yet any printing of the Resources that a Watchpoint is
implemented in terms of ("watchpoint list", or
SBWatchpoint::GetDescription).
"watchpoint set var" and "watchpoint set expression" take a size
argument which was previously 1, 2, 4, or 8 (an enum). I've changed this
to an unsigned int. Most hardware implementations can only watch 1, 2,
4, 8 byte ranges, but with Resources we'll allow a user to ask for
different sized watchpoints and set them in hardware-expressble terms
soon.
I've annotated areas where I know there is work still needed with
LWP_TODO that I'll be working on once this is landed.
I've tested this on aarch64 macOS, aarch64 Linux, and Intel macOS.
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
When setting conditional breakpoints, we currently assume that a call to
UserExpression::Parse() can be cached and resued multiple times. This
may not be true for every user expression. Add a new method so
subclasses of UserExpression can customize if they are parseable or not.
The Watchpoint and Breakpoint objects try to track the hardware index
that was used for them, if they are hardware wp/bp's. The majority of
our debugging goes over the gdb remote serial protocol, and when we set
the watchpoint/breakpoint, there is no (standard) way for the remote
stub to communicate to lldb which hardware index was used. We have an
lldb-extension packet to query the total number of watchpoint registers.
When a watchpoint is hit, there is an lldb extension to the stop reply
packet (documented in lldb-gdb-remote.txt) to describe the watchpoint
including its actual hardware index,
<addr within wp range> <wp hw index> <actual accessed address>
(the third field is specifically needed for MIPS). At this point, if the
stub reported these three fields (the stub is only required to provide
the first), we can know the actual hardware index for this watchpoint.
Breakpoints are worse; there's never any way for us to be notified about
which hardware index was used. Breakpoints got this as a side effect of
inherting from StoppointSite with Watchpoints.
We expose the watchpoint hardware index through "watchpoint list -v" and
through SBWatchpoint::GetHardwareIndex.
With my large watchpoint support, there is no *single* hardware index
that may be used for a watchpoint, it may need multiple resources. Also
I don't see what a user is supposed to do with this information, or an
IDE. Knowing the total number of watchpoint registers on the target, and
knowing how many Watchpoint Resources are currently in use, is helpful.
Knowing how many Watchpoint Resources
a single user-specified watchpoint needed to be implemented is useful.
But knowing which registers were used is an implementation detail and
not available until we hit the watchpoint when using gdb remote serial
protocol.
So given all that, I'm removing watchpoint hardware index numbers. I'm
changing the SB API to always return -1.
This patch changes the interface of
StructuredData::Array::GetItemAtIndexAsString to return a
`std::optional<llvm::StringRef>` instead of taking an out parameter.
More generally, this commit serves as proposal that we change all of the
sibling APIs (`GetItemAtIndexAs`) to do the same thing. The reason this
isn't one giant patch is because it is rather unwieldy changing just one
of these, so if this is approved, I will do all of the other ones as
individual follow-ups.
BreakpointResolver::CreateFromStructuredData returns a
BreakpointResolverSP, but all of the subclasses return raw pointers.
Instead of creating a raw pointer and shoving it into a shared pointer,
it seems reasonable to just create the shared pointer directly.
This reverts commit a7b78cac9a.
With updates to the tests.
TestWatchTaggedAddress.py: Updated the expected watchpoint types,
though I'm not sure there should be a differnt default for the two
ways of setting them, that needs to be confirmed.
TestStepOverWatchpoint.py: Skipped this everywhere because I think
what used to happen is you couldn't put 2 watchpoints on the same
address (after alignment). I guess that this is now allowed because
modify watchpoints aren't accounted for, but likely should be.
Needs investigating.
Watchpoints in lldb can be either 'read', 'write', or 'read/write'. This
is exposing the actual behavior of hardware watchpoints. gdb has a
different behavior: a "write" type watchpoint only stops when the
watched memory region *changes*.
A user is using a watchpoint for one of three reasons:
1. Want to find what is changing/corrupting this memory.
2. Want to find what is writing to this memory.
3. Want to find what is reading from this memory.
I believe (1) is the most common use case for watchpoints, and it
currently can't be done in lldb -- the user needs to continue every time
the same value is written to the watched-memory manually. I think gdb's
behavior is the correct one. There are some use cases where a developer
wants to find every function that writes/reads to/from a memory region,
regardless of value, I want to still allow that functionality.
This is also a bit of groundwork for my large watchpoint support
proposal
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
where I will be adding support for AArch64 MASK watchpoints which watch
power-of-2 memory regions. A user might ask to watch 24 bytes, and a
MASK watchpoint stub can do this with a 32-byte MASK watchpoint if it is
properly aligned. And we need to ignore writes to the final 8 bytes of
that watched region, and not show those hits to the user.
This patch adds a new 'modify' watchpoint type and it is the default.
Re-landing this patch after addressing testsuite failures found in CI on
Linux, Intel machines, and windows.
rdar://108234227
Watchpoints in lldb can be either 'read', 'write', or 'read/write'. This
is exposing the actual behavior of hardware watchpoints. gdb has a
different behavior: a "write" type watchpoint only stops when the
watched memory region *changes*.
A user is using a watchpoint for one of three reasons:
1. Want to find what is changing/corrupting this memory.
2. Want to find what is writing to this memory.
3. Want to find what is reading from this memory.
I believe (1) is the most common use case for watchpoints, and it
currently can't be done in lldb -- the user needs to continue every time
the same value is written to the watched-memory manually. I think gdb's
behavior is the correct one. There are some use cases where a developer
wants to find every function that writes/reads to/from a memory region,
regardless of value, I want to still allow that functionality.
This is also a bit of groundwork for my large watchpoint support
proposal
https://discourse.llvm.org/t/rfc-large-watchpoint-support-in-lldb/72116
where I will be adding support for AArch64 MASK watchpoints which watch
power-of-2 memory regions. A user might ask to watch 24 bytes, and a
MASK watchpoint stub can do this with a 32-byte MASK watchpoint if it is
properly aligned. And we need to ignore writes to the final 8 bytes of
that watched region, and not show those hits to the user.
This patch adds a new 'modify' watchpoint type and it is the default.
rdar://108234227
