[AArch64][PAC] Eliminate excessive MOVs when computing blend (#115185)
As function calls do not generally preserve X16 and X17, it is beneficial
to allow AddrDisc operand of BLRA instruction to reside in these
registers and make use of this condition when computing the
discriminator.
This can save up to two MOVs in cases such as loading a (signed) virtual
function pointer via a (signed) pointer to vtable, for example
ldr x9, [x16]
mov x8, x16
mov x17, x8
movk x17, #34646, lsl #48
blraa x9, x17
can be simplified to
ldr x8, [x16]
movk x16, #34646, lsl #48
blraa x8, x16
Welcome to the LLVM project!
This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.
C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.
Other components include: the libc++ C++ standard library, the LLD linker, and more.
Consult the Getting Started with LLVM page for information on building and running LLVM.
For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.
The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.