search

Windows-on-ARM-Experiments / gcc-woarm64

Fork of gcc containing fixes for Windows on ARM64.
GNU General Public License v2.0
8 stars 1 forks source link

Question about x18 reservation #18

Closed trcrsired closed 2 months ago

trcrsired commented 2 months ago

Does that mean the compiler can never use x18 again, or is it free to store and load x18 when registers are not enough?

I wrote algorithms like sha512, which heavily relies on using every register.

Blackhex commented 2 months ago

Hello.

Thank you for using our experimental toolchain. The X18 register is reserved for Windows operating system by Arm64 Windows ABI conventions (https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions?view=msvc-170#integer-registers) and no user-space code should use it.