Revert "[NFC] Improve FileSpec internal APIs and usage in preparation for adding caching of resolved/absolute." and follow-ups

This reverts commit 9429b67b8e300e638d7828bbcb95585f85c4df4d.

It broke

Revert "[NFC] Improve FileSpec internal APIs and usage in preparation for adding caching of resolved/absolute." and follow-ups

This reverts commit 9429b67b8e300e638d7828bbcb95585f85c4df4d.

It broke the build on Windows, see comments on https://reviews.llvm.org/D130309

It also reverts these follow-ups:

Revert "Fix buildbot breakage after https://reviews.llvm.org/D130309."
This reverts commit f959d815f4637890ebbacca379f1c38ab47e4e14.

Revert "Fix buildbot breakage after https://reviews.llvm.org/D130309."
This reverts commit 0bbce7a4c2d2bff622bdadd4323f93f5d90e6d24.

Revert "Cache the value for absolute path in FileSpec."
This reverts commit dabe877248b85b34878e75d5510339325ee087d0.

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[NFC] Improve FileSpec internal APIs and usage in preparation for adding caching of resolved/absolute.

The FileSpect APIs allow users to modify instance variables directly by getting a non const ref

[NFC] Improve FileSpec internal APIs and usage in preparation for adding caching of resolved/absolute.

The FileSpect APIs allow users to modify instance variables directly by getting a non const reference to the directory and filename instance variables. This makes it impossibly to control all of the times the FileSpec object is modified so we can clear the cache. This patch modifies the APIs of FileSpec so no one can modify the directory or filename directly by adding set accessors and by removing the get accessors that are non const.

Many clients were using FileSpec::GetCString(...) which returned a unique C string from a ConstString'ified version of the result of GetPath() which returned a std::string. This caused many locations to use this convenient function incorrectly and could cause many strings to be added to the constant string pool that didn't need to. Most clients were converted to using FileSpec::GetPath().c_str() when possible. Other clients were modified to use the newly renamed version of this function which returns an actualy ConstString:
ConstString FileSpec::GetPathAsConstString(bool denormalize = true) const;

This avoids the issue where people were getting an already uniqued "const char *" that came from a ConstString only to put the "const char *" back into a "ConstString" object. By returning the ConstString instead of a "const char *" clients can be more efficient with the result.

The patch:
- Removes the non const GetDirectory() and GetFilename() get accessors
- Adds set accessors to replace the above functions: SetDirectory() and SetFilename().
- Adds ClearDirectory() and ClearFilename() to replace usage of the FileSpec::GetDirectory().Clear()/FileSpec::GetFilename().Clear() call sites
- Fixed all incorrect usage of FileSpec::GetCString() to use FileSpec::GetPath().c_str() where appropriate, and updated other call sites that wanted a ConstString to use the newly returned ConstString appropriately and efficiently.

Differential Revision: https://reviews.llvm.org/D130309

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[NFC][lldb][trace] Rename trace session to trace bundle

As previously discussed with @jj10306, we didn't really have a name for
the post-mortem (or offline) trace session representation, which is in

[NFC][lldb][trace] Rename trace session to trace bundle

As previously discussed with @jj10306, we didn't really have a name for
the post-mortem (or offline) trace session representation, which is in
fact a folder with a bunch of files. We decided to call this folder
"trace bundle", and the main JSON file in it "trace bundle description
file". This naming is pretty decent, so I'm refactoring all the existing
code to account for that.

Differential Revision: https://reviews.llvm.org/D128484

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Add LoadTraceFromFile to SBDebugger and SBTrace

Add trace load functionality to SBDebugger via the `LoadTraceFromFile` method.
Update intelpt test case class to have `testTraceLoad` method so we can

Add LoadTraceFromFile to SBDebugger and SBTrace

Add trace load functionality to SBDebugger via the `LoadTraceFromFile` method.
Update intelpt test case class to have `testTraceLoad` method so we can take advantage of
the testApiAndSB decorator to test both the CLI and SB without duplicating code.

Differential Revision: https://reviews.llvm.org/D128107

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[trace][intelpt] Support system-wide tracing [22] - Some final touches

Having a member variable TraceIntelPT * makes it look as if it was
optional. I'm using instead a weak_ptr to indicate that it's

[trace][intelpt] Support system-wide tracing [22] - Some final touches

Having a member variable TraceIntelPT * makes it look as if it was
optional. I'm using instead a weak_ptr to indicate that it's not
optional and the object is under the ownership of TraceIntelPT.

Besides that, I've simplified the Perf aux and data buffers copying by
using vector.insert.

I'm also renaming Lookup2 to Lookup. The 2 in the name is confusing.

Differential Revision: https://reviews.llvm.org/D127881

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[trace][intelpt] Support system-wide tracing [20] - Rename some fields in the schema

As discusses offline with @jj10305, we are updating some naming used throughout the code, specially in the json s

[trace][intelpt] Support system-wide tracing [20] - Rename some fields in the schema

As discusses offline with @jj10305, we are updating some naming used throughout the code, specially in the json schema

- traceBuffer -> iptTrace
- core -> cpu

Differential Revision: https://reviews.llvm.org/D127817

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[trace][intelpt] Support system-wide tracing [18] - some more improvements

This applies the changes requested for diff 12.

- use DenseMap<ConstString, _> instead of std::unordered_map<ConstString,

[trace][intelpt] Support system-wide tracing [18] - some more improvements

This applies the changes requested for diff 12.

- use DenseMap<ConstString, _> instead of std::unordered_map<ConstString, _>, which is more idiomatic and possibly performant.
- deduplicate some code in Trace.cpp by using helper functions for fetching in maps
- stop using size and offset when fetching binary data, because we in fact read the entire buffers all the time. If we ever need streaming, we can implement it then. Now, the size is used only to check that we are getting the correct amount of data. This is useful because in some cases determining the size doesn't involve fetching the actual data.
- added back the x86_64 macro to the perf tests
- added more documentation
- simplified some file handling
- fixed some comments

Differential Revision: https://reviews.llvm.org/D127752

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[trace][intelpt] Support system-wide tracing [17] - Some improvements

This improves several things and addresses comments up to the diff [11] in this stack.

- Simplify many functions to receive les

[trace][intelpt] Support system-wide tracing [17] - Some improvements

This improves several things and addresses comments up to the diff [11] in this stack.

- Simplify many functions to receive less parameters that they can identify easily
- Create Storage classes for Trace and TraceIntelPT that can make it easier to reason about what can change with live process refreshes and what cannot.
- Don't cache the perf zero conversion numbers in lldb-server to make sure we get the most up-to-date numbers.
- Move the thread identifaction from context switches to the bundle parser, to leave TraceIntelPT simpler. This also makes sure that the constructor of TraceIntelPT is invoked when the entire data has been checked to be correct.
- Normalize all bundle paths before the Processes, Threads and Modules are created, so that they can assume that all paths are correct and absolute
- Fix some issues in the tests. Now they all pass.
- return the specific instance when constructing PerThread and MultiCore processor tracers.
- Properly implement IntelPTMultiCoreTrace::TraceStart.
- Improve some comments.
- Use the typedef ContextSwitchTrace more often for clarity.
- Move CreateContextSwitchTracePerfEvent to Perf.h as a utility function.
- Synchronize better the state of the context switch and the intel pt
perf events.
- Use a booblean instead of an enum for the PerfEvent state.

Differential Revision: https://reviews.llvm.org/D127456

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[trace][intelpt] Support system-wide tracing [16] - Create threads automatically from context switch data in the post-mortem case

For some context, The context switch data contains information of wh

[trace][intelpt] Support system-wide tracing [16] - Create threads automatically from context switch data in the post-mortem case

For some context, The context switch data contains information of which threads were
executed by each traced process, therefore it's not necessary to specify
them in the trace file.

So this diffs adds support for that automatic feature. Eventually we
could include it to live processes as well.

Differential Revision: https://reviews.llvm.org/D127001

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[trace][intelpt] Support system-wide tracing [14] - Decode per cpu

This is the final functional patch to support intel pt decoding per cpu.
It works by doing the following:

- First, all context swi

[trace][intelpt] Support system-wide tracing [14] - Decode per cpu

This is the final functional patch to support intel pt decoding per cpu.
It works by doing the following:

- First, all context switches are split by tid and sorted in order. This produces a list of continuous executes per thread per core.
- Then, all intel pt subtraces are split by PSB boundaries and assigned to individual thread continuous executions on the same core by doing simple TSC-based comparisons.
- With this, we have, per thread, a sorted list of continuous executions each one with a list of intel pt subtraces. Up to this point, this is really fast because no instructions were actually decoded.
- Then, each thread can be decoded by traversing their continuous executions and intel pt subtraces. An advantage of having these continuous executions is that we can identify if a continuous exexecution doesn't have intel pt data, and thus has a gap in it. We can later to more sofisticated comparisons to identify if within a continuous execution there are gaps.

I'm adding a test as well.

Differential Revision: https://reviews.llvm.org/D126394

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[trace][intelpt] Support system-wide tracing [13] - Add context switch decoding

- Add the logic that parses all cpu context switch traces and produces blocks of continuous executions, which will be

[trace][intelpt] Support system-wide tracing [13] - Add context switch decoding

- Add the logic that parses all cpu context switch traces and produces blocks of continuous executions, which will be later used to assign intel pt subtraces to threads and to identify gaps. This logic can also identify if the context switch trace is malformed.
- The continuous executions blocks are able to indicate when there were some contention issues when producing the context switch trace. See the inline comments for more information.
- Update the 'dump info' command to show information and stats related to the multicore decoding flow, including timing about context switch decoding.
- Add the logic to conver nanoseconds to TSCs.
- Fix a bug when returning the context switches. Now they data returned makes sense and even empty traces can be returned from lldb-server.
- Finish the necessary bits for loading and saving a multi-core trace bundle from disk.
- Change some size_t to uint64_t for compatibility with 32 bit systems.

Tested by saving a trace session of a program that sleeps 100 times, it was able to produce the following 'dump info' text:

```
(lldb) trace load /tmp/trace3/trace.json (lldb) thread trace dump info Trace technology: intel-pt

thread #1: tid = 4192415
Total number of instructions: 1

Memory usage:
Total approximate memory usage (excluding raw trace): 2.51 KiB
Average memory usage per instruction (excluding raw trace): 2573.00 bytes

Timing for this thread:

Timing for global tasks:
Context switch trace decoding: 0.00s

Events:
Number of instructions with events: 0
Number of individual events: 0

Multi-core decoding:
Total number of continuous executions found: 2499
Number of continuous executions for this thread: 102

Errors:
Number of TSC decoding errors: 0
```

Differential Revision: https://reviews.llvm.org/D126267

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[trace][intelpt] Support system-wide tracing [12] - Support multi-core trace load and save

:q!
This diff is massive, but it's because it connects the client with lldb-server
and also ensures that th

[trace][intelpt] Support system-wide tracing [12] - Support multi-core trace load and save

:q!
This diff is massive, but it's because it connects the client with lldb-server
and also ensures that the postmortem case works.

- Flatten the postmortem trace schema. The reason is that the schema has become quite complex due to the new multicore case, which defeats the original purpose of having a schema that could work for every trace plug-in. At this point, it's better that each trace plug-in defines it's own full schema. This means that the only common field is "type".
-- Because of this new approach, I merged the "common" trace load and saving functionalities into the IntelPT one. This simplified the code quite a bit. If we eventually implement another trace plug-in, we can see then what we could reuse.
-- The new schema, which is flattened, has now better comments and is parsed better. A change I did was to disallow hex addresses, because they are a bit error prone. I'm asking now to print the address in decimal.
-- Renamed "intel" to "GenuineIntel" in the schema because that's what you see in /proc/cpuinfo.
- Implemented reading the context switch trace data buffer. I had to do
some refactors to do that cleanly.
-- A major change that I did here was to simplify the perf_event circular buffer reading logic. It was too complex. Maybe the original Intel author had something different in mind.
- Implemented all the necessary bits to read trace.json files with per-core data.
- Implemented all the necessary bits to save to disk per-core trace session.
- Added a test that ensures that parsing and saving to disk works.

Differential Revision: https://reviews.llvm.org/D126015

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[trace][intelpt] Support system-wide tracing [11] - Read warnings and perf conversion in the client

- Add logging for when the live state of the process is refreshed
- Move error handling of the liv

[trace][intelpt] Support system-wide tracing [11] - Read warnings and perf conversion in the client

- Add logging for when the live state of the process is refreshed
- Move error handling of the live state refreshing to Trace from TraceIntelPT. This allows refreshing to fail either at the plug-in level or at the base class level. The error is cached and it can be gotten every time RefreshLiveProcessState is invoked.
- Allow DoRefreshLiveProcessState to handle plugin-specific parameters.
- Add some encapsulation to prevent TraceIntelPT from accessing variables belonging to Trace.

Test done via logging:

```
(lldb) b main
Breakpoint 1: where = a.out`main + 20 at main.cpp:27:20, address = 0x00000000004023d9
(lldb) r
Process 2359706 launched: '/home/wallace/a.out' (x86_64)
Process 2359706 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004023d9 a.out`main at main.cpp:27:20
24 };
25
26 int main() {
-> 27 std::vector<int> vvv;
28 for (int i = 0; i < 100000; i++)
29 vvv.push_back(i);
30
(lldb) process trace start (lldb) log enable lldb target -F(lldb) n
Process 2359706 stopped
* thread #1, name = 'a.out', stop reason = step over
frame #0: 0x00000000004023e8 a.out`main at main.cpp:28:12
25
26 int main() {
27 std::vector<int> vvv;
-> 28 for (int i = 0; i < 100000; i++)
29 vvv.push_back(i);
30
31 std::deque<int> dq1 = {1, 2, 3};
(lldb) thread trace dump instructions -c 2 -t Trace.cpp:RefreshLiveProcessState Trace::RefreshLiveProcessState invoked
TraceIntelPT.cpp:DoRefreshLiveProcessState TraceIntelPT found tsc conversion information
thread #1: tid = 2359706
a.out`std::vector<int, std::allocator<int>>::vector() + 26 at stl_vector.h:395:19
54: [tsc=unavailable] 0x0000000000403a7c retq
```

See the logging lines at the end of the dump. They indicate that refreshing happened and that perf conversion information was found.

Differential Revision: https://reviews.llvm.org/D125943

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[trace][intelpt] Support system-wide tracing [4] - Support per core tracing on lldb-server

This diffs implements per-core tracing on lldb-server. It also includes tests that ensure that tracing can

[trace][intelpt] Support system-wide tracing [4] - Support per core tracing on lldb-server

This diffs implements per-core tracing on lldb-server. It also includes tests that ensure that tracing can be initiated from the client and that the jLLDBGetState ppacket returns the list of trace buffers per core.

This doesn't include any decoder changes.

Finally, this makes some little changes here and there improving the existing code.

A specific piece of code that can't reliably be tested is when tracing
per core fails due to permissions. In this case we add a
troubleshooting message and this is the manual test:

```
/proc/sys/kernel/perf_event_paranoid set to 1

(lldb) process trace start --per-core-tracing error: perf event syscall failed: Permission denied
You might need that /proc/sys/kernel/perf_event_paranoid has a value of 0 or -1.
``

Differential Revision: https://reviews.llvm.org/D124858

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[NFC][lldb][trace] Use uint64_t when decoding and enconding json

llvm's json parser supports uint64_t, so let's better use it for the
packets being sent between lldb and lldb-server instead of using

[NFC][lldb][trace] Use uint64_t when decoding and enconding json

llvm's json parser supports uint64_t, so let's better use it for the
packets being sent between lldb and lldb-server instead of using int64_t
as an intermediate type, which might be error-prone.

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Revert "[NFC][lldb][trace] Use uint64_t when decoding and enconding json"

This reverts commit 9d2dd6d7622335ba9c19b55ac7d463cf662cab0d.

Reverting because this exposes an issue in the uint64_t json

Revert "[NFC][lldb][trace] Use uint64_t when decoding and enconding json"

This reverts commit 9d2dd6d7622335ba9c19b55ac7d463cf662cab0d.

Reverting because this exposes an issue in the uint64_t json parser.

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[NFC][lldb][trace] Use uint64_t when decoding and enconding json

llvm's json parser supports uint64_t, so let's better use it for the
packets being sent between lldb and lldb-server instead of using

[NFC][lldb][trace] Use uint64_t when decoding and enconding json

llvm's json parser supports uint64_t, so let's better use it for the
packets being sent between lldb and lldb-server instead of using int64_t
as an intermediate type, which might be error-prone.

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[trace][intel pt] Create a common accessor for live and postmortem data

Some parts of the code have to distinguish between live and postmortem threads
to figure out how to get some data, e.g. thread

[trace][intel pt] Create a common accessor for live and postmortem data

Some parts of the code have to distinguish between live and postmortem threads
to figure out how to get some data, e.g. thread trace buffers. This makes the
code less generic and more error prone. An example of that is that we have
two different decoders: LiveThreadDecoder and PostMortemThreadDecoder. They
exist because getting the trace bufer is different for each case.

The problem doesn't stop there. Soon we'll have even more kinds of data, like
the context switch trace, whose fetching will be different for live and post-
mortem processes.

As a way to fix this, I'm creating a common API for accessing thread data,
which is able to figure out how to handle the postmortem and live cases on
behalf of the caller. As a result of that, I was able to eliminate the two
decoders and unify them into a simpler one. Not only that, our TraceSave
functionality only worked for live threads, but now it can also work for
postmortem processes, which might be useful now, but it might in the future.

This common API is OnThreadBinaryDataRead. More information in the inline
documentation.

Differential Revision: https://reviews.llvm.org/D123281

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[trace] Use vector instead of ArrayRef when reading data

I incorrectly returned an ArrayRef when the underlying object didn't own
the data. Instead, returning a vector<uint8_t> is what we should do.

[trace] Use vector instead of ArrayRef when reading data

I incorrectly returned an ArrayRef when the underlying object didn't own
the data. Instead, returning a vector<uint8_t> is what we should do.

This fixes an issue when trying to access an intel-pt trace buffer
larger than 16 MB.

repro
```
go to a breakpoint
thread trace start -s 16777216
n
thread trace dump instructions # this doesn't fail anymore
```

Differential Revision: https://reviews.llvm.org/D122192

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[lldb] Remove ConstString from SymbolVendor, Trace, TraceExporter, UnwindAssembly, MemoryHistory and InstrumentationRuntime plugin names

[lldb] Return StringRef from PluginInterface::GetPluginName

There is no reason why this function should be returning a ConstString.

While modifying these files, I also fixed several instances where

[lldb] Return StringRef from PluginInterface::GetPluginName

There is no reason why this function should be returning a ConstString.

While modifying these files, I also fixed several instances where
GetPluginName and GetPluginNameStatic were returning different strings.

I am not changing the return type of GetPluginNameStatic in this patch, as that
would necessitate additional changes, and this patch is big enough as it is.

Differential Revision: https://reviews.llvm.org/D111877

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[LLDB] Move Trace-specific classes into separate library

These two classes, TraceSessionFileParser and ThreadPostMortemTrace,
seem to be useful primarily for tracing. Currently it looks like
intel-p

[LLDB] Move Trace-specific classes into separate library

These two classes, TraceSessionFileParser and ThreadPostMortemTrace,
seem to be useful primarily for tracing. Currently it looks like
intel-pt is the sole user of these, but that other tracing plugins could
be written in the future that take advantage of these. Unfortunately
with them in Target, there is a dependency on PluginProcessUtility. I'd
like to sever that dependency, so I moved them into a `TraceCommon`
plugin.

Differential Revision: https://reviews.llvm.org/D105649

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[trace][intel pt] Implement the Intel PT cursor

D104422 added the interface for TraceCursor, which is the main way to traverse instructions in a trace. This diff implements the corresponding cursor

[trace][intel pt] Implement the Intel PT cursor

D104422 added the interface for TraceCursor, which is the main way to traverse instructions in a trace. This diff implements the corresponding cursor class for Intel PT and deletes the now obsolete code.

Besides that, the logic for the "thread trace dump instructions" was adapted to use this cursor (pretty much I ended up moving code from Trace.cpp to TraceCursor.cpp). The command by default traverses the instructions backwards, and if the user passes --forwards, then it's not forwards. More information about that is in the Options.td file.

Regarding the Intel PT cursor. All Intel PT cursors for the same thread share the same DecodedThread instance. I'm not yet implementing lazy decoding because we don't need it. That'll be for later. For the time being, the entire thread trace is decoded when the first cursor for that thread is requested.

Differential Revision: https://reviews.llvm.org/D105531

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[trace] Add a TraceCursor class

As a follow up of D103588, I'm reinitiating the discussion with a new proposal for traversing instructions in a trace which uses the feedback gotten in that diff.

Se

[trace] Add a TraceCursor class

As a follow up of D103588, I'm reinitiating the discussion with a new proposal for traversing instructions in a trace which uses the feedback gotten in that diff.

See the embedded documentation in TraceCursor for more information. The idea is to offer an OOP way to traverse instructions exposing a minimal interface that makes no assumptions on:

- the number of instructions in the trace (i.e. having indices for instructions might be impractical for gigantic intel-pt traces, as it would require to decode the entire trace). This renders the use of indices to point to instructions impractical. Traces are big and expensive, and the consumer should try to do look linear lookups (forwards and/or backwards) and avoid random accesses (the API could be extended though, but for now I want to dicard that funcionality and leave the API extensible if needed).
- the way the instructions are represented internally by each Trace plug-in. They could be mmap'ed from a file, exist in plain vector or generated on the fly as the user requests the data.
- the actual data structure used internally for each plug-in. Ideas like having a struct TraceInstruction have been discarded because that would make the plug-in follow a certain data type, which might be costly. Instead, the user can ask the cursor for each independent property of the instruction it's pointing at.

The way to get a cursor is to ask Trace.h for the end or being cursor or a thread's trace.

There are some benefits of this approach:
- there's little cost to create a cursor, and this allows for lazily decoding a trace as the user requests data.
- each trace plug-in could decide how to cache the instructions it generates. For example, if a trace is small, it might decide to keep everything in memory, or if the trace is massive, it might decide to keep around the last thousands of instructions to speed up local searches.
- a cursor can outlive a stop point, which makes trace comparison for live processes feasible. An application of this is to compare profiling data of two runs of the same function, which should be doable with intel pt.

Differential Revision: https://reviews.llvm.org/D104422

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[trace][intel-pt] Create basic SB API

This adds a basic SB API for creating and stopping traces.
Note: This doesn't add any APIs for inspecting individual instructions. That'd be a more complicated

[trace][intel-pt] Create basic SB API

This adds a basic SB API for creating and stopping traces.
Note: This doesn't add any APIs for inspecting individual instructions. That'd be a more complicated change and it might be better to enhande the dump functionality to output the data in binary format. I'll leave that for a later diff.

This also enhances the existing tests so that they test the same flow using both the command interface and the SB API.

I also did some cleanup of legacy code.

Differential Revision: https://reviews.llvm.org/D103500

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