[VL] Fix StdMemoryAllocator::allocateZeroFilled byte accounting

[LuciferYang]

What changes are proposed in this pull request?

Fix incorrect byte accounting in StdMemoryAllocator::allocateZeroFilled. The method calls std::calloc(nmemb, size) which allocates nmemb * size bytes, but bytes_ was only incremented by size instead of nmemb * size.

This is consistent with ListenableMemoryAllocator::allocateZeroFilled, which already correctly tracks size * nmemb.

How was this patch tested?

Added a unit test StdMemoryAllocator.allocateZeroFilledAccounting that verifies allocateZeroFilled(10, 64, &buf) correctly tracks 640 bytes.

Was this patch authored or co-authored using generative AI tooling?

Generated-by: Claude Code

[Copilot]

Pull request overview

Fixes incorrect memory-usage accounting in StdMemoryAllocator::allocateZeroFilled by tracking nmemb * size bytes (matching the actual calloc allocation size), and adds a unit test to prevent regression.

Changes:

• Correct StdMemoryAllocator::allocateZeroFilled byte tracking from size to nmemb * size.
• Add StdMemoryAllocator.allocateZeroFilledAccounting unit test validating the accounting behavior.
• Register the new test in cpp/core/tests/CMakeLists.txt.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
cpp/core/memory/MemoryAllocator.cc	Fixes allocateZeroFilled byte accounting to reflect the true allocation size.
cpp/core/tests/MemoryAllocatorTest.cc	Adds a regression test for allocateZeroFilled byte accounting.
cpp/core/tests/CMakeLists.txt	Adds the new memory allocator test target to the CMake test list.

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[Copilot]

nmemb * size is computed in int64_t, which can overflow and cause undefined behavior (and incorrect accounting) for large allocations even if calloc succeeds. Consider computing the total bytes using checked multiplication (e.g., via __int128/overflow check) and GLUTEN_CHECK that it fits in int64_t before updating bytes_.

[Copilot]

The test hard-codes 640 in multiple places. To avoid drift if the inputs change, compute an expectedBytes = 10 * 64 once and use it for the accounting assertion and for free(...) (and assert that free returns true to validate the API contract).

Suggested change

	void* buf = nullptr;
	bool ok = allocator.allocateZeroFilled(10, 64, &buf);
	ASSERT_TRUE(ok);
	ASSERT_NE(buf, nullptr);
	ASSERT_EQ(allocator.getBytes(), 640);
	allocator.free(buf, 640);
	const size_t expectedBytes = 10 * 64;
	void* buf = nullptr;
	bool ok = allocator.allocateZeroFilled(10, 64, &buf);
	ASSERT_TRUE(ok);
	ASSERT_NE(buf, nullptr);
	ASSERT_EQ(allocator.getBytes(), expectedBytes);
	ASSERT_TRUE(allocator.free(buf, expectedBytes));