C++: Handle Arm SVE in the IR

[jketema]

Observe that MS calculator is currently broken in DCA. I don't think missing out on the project is critical for this PR. I've opened microsoft/calculator#2347 to hopefully get this resolved.

[Copilot]

Pull Request Overview

Adds support for Arm Scalable Vector Extension (SVE) types in the intermediate representation generation and updates related tests.

• Renames and extends NEON tests (arm.cpp → arm_neon.cpp) and adds a new arm_sve.cpp test.
• Updates expected IR and AST outputs for both NEON and SVE patterns.
• Treats ScalableVectorType as opaque (size 0) and includes it in const-propagation (isDeeplyConstBelow) rules in the QL IR definitions.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
cpp/ql/test/library-tests/ir/ir/raw_ir.expected	Updated expected raw IR for NEON and added SVE cases
cpp/ql/test/library-tests/ir/ir/aliased_ir.expected	Updated aliased IR expectations for NEON and SVE
cpp/ql/test/library-tests/ir/ir/PrintAST.expected	Updated AST print expectations for NEON and SVE
cpp/ql/test/library-tests/ir/ir/arm_neon.cpp	New NEON test source
cpp/ql/test/library-tests/ir/ir/arm_sve.cpp	New SVE test source
cpp/ql/lib/semmle/code/cpp/ir/internal/CppType.qll	Treat ScalableVectorType as size-0 in getTypeSizeWorkaround and isOpaqueType
cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/SideEffects.qll	Include ScalableVectorType in isDeeplyConstBelow

Comments suppressed due to low confidence (2)

cpp/ql/lib/semmle/code/cpp/ir/internal/CppType.qll:34

• [nitpick] Add a QLDoc comment above this clause to explain why ScalableVectorType is treated as size 0 (opaque) and when this fallback might need revisiting.

      type instanceof ScalableVectorType and

cpp/ql/lib/semmle/code/cpp/ir/internal/CppType.qll:34

• Add or extend a unit test to verify that getTypeSizeWorkaround returns 0 for ScalableVectorType, ensuring the new fallback is exercised.

      type instanceof ScalableVectorType and

[Copilot]

[nitpick] Consider grouping the vector-type const checks (GNUVectorType and ScalableVectorType) into a single reusable predicate to reduce duplication.

Suggested change

	isDeeplyConst(t.(GNUVectorType).getBaseType())
	or
	isDeeplyConst(t.(ScalableVectorType).getBaseType())
	or
	isVectorType(t) and isDeeplyConst(t.getBaseType())
	or