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Patch MSVC + OpenMP + double-or-quad precision + tests #732

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Merged
TysonRayJones merged 5 commits into from
Apr 22, 2026
Merged

Patch MSVC + OpenMP + double-or-quad precision + tests #732

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799c15d
Patching MSVC + OpenMP
TysonRayJones Apr 22, 2026
b7aca62
trigger CI
TysonRayJones Apr 22, 2026
ff0c6c8
Pass all applyPauliUponAmpPair args by ref
TysonRayJones Apr 22, 2026
4a1e272
removing CI trigger
TysonRayJones Apr 22, 2026
de3ba39
Add warning to header doc
TysonRayJones Apr 22, 2026
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1 change: 0 additions & 1 deletion .github/workflows/compile.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,6 @@ on:
branches:
- main
- devel
- unifying-base-qcomp
pull_request:
branches:
- main
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16 changes: 11 additions & 5 deletions quest/src/cpu/cpu_subroutines.cpp
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Expand Up @@ -3,7 +3,9 @@
* as mirrored by gpu_subroutines.cpp, and called by accelerator.cpp.
*
* These 'hot-loop' functions use cpu_qcomp arithmetic operators, in lieu of qcomp
* (i.e. std::complex) which has compiler-specific performance pitfalls.
* (i.e. std::complex) which has compiler-specific performance pitfalls. BEWARE
* that passing a cpu_qcomp by-value to a function inside an OpenMP parallel region
* can cause MSVC to crash during compilation, so be sure to pass by reference!
*
* Some of these definitions are templated, defining multiple versions optimised
* (at compile-time) for handling different numbers of input qubits; such functions
Expand Down Expand Up @@ -938,12 +940,16 @@ template void cpu_densmatr_allTargDiagMatr_sub<true, false, true, false> (Qure

template <int NumTargs>
INLINE void applyPauliUponAmpPair(
cpu_qcomp* amps, qindex v, qindex i0, int* indXY, int numXY,
qindex maskXY, qindex maskYZ, cpu_qcomp ampFac, cpu_qcomp pairAmpFac
cpu_qcomp* amps, qindex& v, qindex& i0, int* indXY, int& numXY,
qindex& maskXY, qindex& maskYZ, cpu_qcomp& ampFac, cpu_qcomp& pairAmpFac
) {
// this is a subroutine of cpu_statevector_anyCtrlPauliTensorOrGadget_subA() below
// This is a subroutine of cpu_statevector_anyCtrlPauliTensorOrGadget_subA() below
// called in a hot-loop (hence it is here inlined) which exists because the caller
// chooses one of two possible OpenMP parallelisation granularities
// chooses one of two possible OpenMP parallelisation granularities. All args are
// pass-by-reference for performance, and because passing the cpu_qcomp types by-
// value causes a stack overflow during compilation with MSVC with OpenMP enabled;
// but only at double and quad precision (single is fine), and only when Catch2 is
// also being compiled (through the tests)... Hours of my life forever lost!

// remind compiler when NumTargs is compile-time to unroll loop in setBits()
SET_VAR_AT_COMPILE_TIME(int, numTargBits, NumTargs, numXY);
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