QAT refactor #1131

troels-im · 2021-09-02T10:41:09Z

QAT refactor

Previous versions of the QAT tool has been unable to correctly handle qubit allocations in following ways:

Recursion would break qubit allocation
Qubit ids would not necessarily be allocated from 0 -> N where N is the number of qubits needed
It would assume that all code (also dead) would perform qubit allocations

Additionally, previous also had following flaws:

The implementation would leave dead code
It did not support verification of the resulting IR.
Examples as tests

This PR fixes these issues.

Dependencies

This PR has no dependencies.

Change log

Deprecation of three passes and introduction of a single configurable pass to perform profile transformations
Pass changed from function pass to module pass.
Support for recursion.
Dead code detection and deletion.
New patterns: Phi and BasicBlock.
Examples as tests: Each example now produces a non-zero exit code if they produce an invalid IR. This means they can be ran during CI as tests.
Activation of name testing during CI.

Examples structure

One of the updates in this PR is a restructuring of examples allowing us to extend them with other frontends and with more examples. Each example can be ran as a test to ensure that the generated IR is valid and that no segfaults or exceptions happen during runtime.

All examples are kept in the examples folder and each example contains subfolders for each of the frontends it supports. Currently, we have two examples:

examples
├── LoopRecursion
│   └── QSharpVersion
└── TeleportChain
    └── QSharpVersion

Example of the improved QAT

In addition to preserving the ability to transform the TeleportChain to the base profile, the new code deal with advanced logic that involves loops and recursion:

    @EntryPoint()
    operation Main(): Int
    {
        use q = Qubit();    
        mutable ret = 1;
        for i in 0..5
        {
            set ret = ret + Calculate(4, q);
        }
        return ret;
    }
    operation Calculate(n: Int, c: Qubit): Int
    {
        use q = Qubit();        
        mutable ret = 2;
        H(q);
        CNOT(c,q);
        if(n != 0)
        {
            set ret = Calculate(n - 1, q) + 2;
        }
        return ret;
    }

which after applying the profile

qat --generate -S --verify-module --profile baseProfile QSharpVersion/qir/Example.ll

comes out as

define void @TeleportChain__Main() local_unnamed_addr #0 {
entry:
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* null, %Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*), %Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*), %Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*), %Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*), %Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* null, %Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*), %Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*), %Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*), %Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*), %Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* null, %Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*), %Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*), %Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*), %Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*), %Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* null, %Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*), %Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*), %Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*), %Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*), %Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* null, %Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*), %Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*), %Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*), %Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*), %Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* null, %Qubit* nonnull inttoptr (i64 1 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 1 to %Qubit*), %Qubit* nonnull inttoptr (i64 2 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 2 to %Qubit*), %Qubit* nonnull inttoptr (i64 3 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 3 to %Qubit*), %Qubit* nonnull inttoptr (i64 4 to %Qubit*))
  tail call void @__quantum__qis__h__body(%Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  tail call void @__quantum__qis__cnot__body(%Qubit* nonnull inttoptr (i64 4 to %Qubit*), %Qubit* nonnull inttoptr (i64 5 to %Qubit*))
  %0 = tail call %String* @__quantum__rt__int_to_string(i64 61)
  ret void
}

src/Passes/Source/Passes/Profile/LibProfile.cpp

src/Passes/examples/QubitAllocationAnalysis/TeleportChain/TeleportChain.qs

bettinaheim

Overall this looks like nice clean up! Given that the code base is still heavily in flux and this goes into a feature branch, I'll approve it based on a quick read through to facilitate further work that builds on this cleaned up version. Once certain passes reach a more steady state we should do a more thorough review than I did.

src/Passes/Source/Apps/Qat/Qat.cpp

bettinaheim · 2021-09-03T05:24:44Z

src/Passes/Source/Apps/Qat/Qat.cpp

+             {"O1", "false"},
+             {"O2", "false"},
+             {"O3", "false"},
+             {"verify-module", "false"}}};


What exactly does verify-module do?

It verifies the module (that the IR is valid) once the transformation was ran.

Is this using built-in llvm infrastructure only or is there anything custom about it? I believe it is the former.

src/Passes/Source/ProfilePass/Profile.hpp

src/Passes/Source/Profiles/BaseProfile.cpp

bettinaheim · 2021-09-03T05:57:12Z

src/Passes/Source/CMakeLists.txt


+microsoft_add_library(ProfilePass)
+target_link_libraries(ProfilePass PRIVATE Rules)
+# microsoft_add_library_tests(ProfilePass)


Why is this not enabled?

We do not have any tests for this component yet aside from the running the examples. All the functionality that does the transformation is tested in the profiles test.

Thanks for the explanation. I assume these are the tests that you wanted to add next week.

src/Passes/Source/ProfilePass/Profile.cpp

bettinaheim · 2021-09-03T06:09:14Z

src/Passes/Source/ProfilePass/Profile.cpp

+
+            if (instr1 == nullptr)
+            {
+                llvm::errs() << "; WARNING: cannot deal with non-instruction replacements\n";


When would this case occur?
How does the tool deal with errors - what happens if the tool produces a warning (e.g. does it fail with a non-zero exit code), and what happens if it produces an error (is there a concept of an error or does it throw in that case)?

I am not sure whether this will ever occur and whether this is even a relevant case to consider. The check is there as a sanity check and will be refactored once I've written a proper error/warning logger. I expect that this would be reported as an internal error.

I agree with and like the idea of reporting it as an internal error.

src/Passes/Source/ProfilePass/Profile.cpp

Co-authored-by: bettinaheim <[email protected]>

troels-im added 20 commits August 31, 2021 08:47

Removing garbage

fd1a5ed

Adding new profile

316272b

Adding module transformation and configurable ruleset

893407c

Adding README

ec3c877

Enabling passing the call tree

4ae8a93

Preparing traversal for function calls

f0dc513

Adding constant folding

5ac1088

Basic branching analysis

2f71437

Updating to follow possible branches

8615017

Deleting dead code

8c65c37

Updating with qubit allocation

d11281e

Fixing replication pass

00d0e59

Fixing qubit array index

3677b69

Refacotring pass

49c4ea2

Refactoring module name

2fac7db

Preparing code deletion

3207a7b

Deleting legacy passes

7a91387

Fixing tests

6f56454

Adding name to TODOs

3050f9c

Fixing tests

08b6a2a

troels-im changed the base branch from main to features/llvm-passes September 2, 2021 10:41

troels-im commented Sep 2, 2021

View reviewed changes

src/Passes/Source/Passes/Profile/LibProfile.cpp Outdated Show resolved Hide resolved

troels-im commented Sep 2, 2021

View reviewed changes

src/Passes/examples/QubitAllocationAnalysis/TeleportChain/TeleportChain.qs Outdated Show resolved Hide resolved

troels-im added 7 commits September 2, 2021 12:46

Removing garbage

309a498

Restructuring teleport example

d5ae180

Refactoring examples

2ac2419

Formatting

b1703d9

Removing dead pass code

643a278

Finish examples refactor

2027fbb

Removing Passes directory

61f54cc

troels-im added 4 commits September 2, 2021 13:23

Deprecating passes templates

24b496f

Removing deprecated tests and activating name checking

06cad4c

Removing outdated documentation

6f8f790

Removing example IR

4964a02

troels-im marked this pull request as ready for review September 2, 2021 11:54

bettinaheim approved these changes Sep 3, 2021

View reviewed changes

troels-im and others added 6 commits September 3, 2021 08:24

Update src/Passes/Source/ProfilePass/Profile.hpp

f360ce0

Co-authored-by: bettinaheim <[email protected]>

Update src/Passes/Source/Profiles/BaseProfile.cpp

d3a7f68

Co-authored-by: bettinaheim <[email protected]>

Update src/Passes/Source/Profiles/RuleSetProfile.cpp

517e1f0

Co-authored-by: bettinaheim <[email protected]>

Update src/Passes/Source/Profiles/BaseProfile.cpp

12dc452

Update src/Passes/Source/Profiles/RuleSetProfile.cpp

4a2d09e

Update src/Passes/Source/Rules/Tests/Unit/SingleQubitAllocation.cpp

eb542f1

Co-authored-by: bettinaheim <[email protected]>

troels-im enabled auto-merge (squash) September 3, 2021 06:51

Fixing style

69bc4cf

troels-im merged commit 6ef1f7c into microsoft:features/llvm-passes Sep 3, 2021

troels-im deleted the feature/qubit-allocation branch September 3, 2021 07:44

QAT refactor #1131

QAT refactor #1131

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QAT refactor

Dependencies

Change log

Examples structure

Example of the improved QAT

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troels-im commented Sep 2, 2021 •

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