MDEV-37000 disable optimization for Aria remove_key() on affected MSVC

[vaintroub]

The Aria remove_key() helper can miscompile in x64 MSVC builds when optimization is enabled, leading to 'Index is corrupt' during DELETE.

Apply the same #pragma optimize("g", off) workaround already used in MyISAM, and limit it to _MSC_VER >= 1930 && _MSC_VER < 1951.

The upper bound for affected MSVC is just the newest MSVC version in VS2026, where the bug is no longer reproducible. Also, MSVC release notes https://learn.microsoft.com/en-us/visualstudio/releases/2026/release-notes list multiple fixes for 19.50 x64 optimizer and codegen bugs.

[gemini-code-assist]

Code Review

This pull request addresses MDEV-37000 by disabling compiler optimization for the remove_key function in both Aria (storage/maria/ma_delete.c) and MyISAM (storage/myisam/mi_delete.c) storage engines when compiled with affected MSVC versions, and adds a corresponding test case. The reviewer suggests adjusting the MSVC version check from _MSC_VER < 1951 to _MSC_VER < 1950 to avoid unnecessarily disabling optimizations on MSVC version 19.50, where the compiler bug is already fixed.

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[gemini-code-assist]

Since the compiler bug is fixed in MSVC version 19.50 (VS2026), that version is not affected. Using _MSC_VER < 1951 unnecessarily disables optimization for version 19.50. Changing the upper bound to _MSC_VER < 1950 ensures that optimization is only disabled on the affected versions (19.30 to 19.49).

#if defined(_MSC_VER) && defined(_M_X64) && _MSC_VER >= 1930 && _MSC_VER < 1950
#pragma optimize("g", off)
#endif

[gemini-code-assist]

Update the upper bound check here as well to match the change in the corresponding #pragma optimize("g", off) block.

#if defined(_MSC_VER) && defined(_M_X64) && _MSC_VER >= 1930 && _MSC_VER < 1950
#pragma optimize("", on)
#endif

[gemini-code-assist]

Since the compiler bug is fixed in MSVC version 19.50 (VS2026), that version is not affected. Using _MSC_VER < 1951 unnecessarily disables optimization for version 19.50. Changing the upper bound to _MSC_VER < 1950 ensures that optimization is only disabled on the affected versions (19.30 to 19.49).

#if defined(_MSC_VER) && defined(_M_X64) && _MSC_VER >= 1930 && _MSC_VER < 1950
#pragma optimize("g", off)
#endif

[gemini-code-assist]

Update the upper bound check here as well to match the change in the corresponding #pragma optimize("g", off) block.

#if defined(_MSC_VER) && defined(_M_X64) && _MSC_VER >= 1930 && _MSC_VER < 1950
#pragma optimize("",on)
#endif

[vuvova]

"miscompile" how? could you be more specific?

[vaintroub]

"miscompile" how? could you be more specific?

Ok, there is is some explanation in the linked ticket, https://jira.mariadb.org/browse/MDEV-27030, not by myself, but by Alexander Miloslavski. With reported bug link . That bug is recently closed as "fixed", and this matches my experience, that on the current VS2026, that test case passes without any deoptimizing pragmas, but on VS2022, it does not.