[PATCH v2 00/07] RISC-V: autovec: Add auto-vectorization support

[Michael Collison <collison@rivosinc.com>]

This series of patches adds foundational support for RISC-V 
autovectorization support. These patches are based on the current 
upstream rvv vector intrinsic support and is not a new implementation. 
Most of the implementation consists of adding the new vector cost model, 
the autovectorization patterns themselves and target hooks.This 
implementation only provides support for integer addition and 
subtraction as a proof of concept. This patch set should not be 
construed to be feature complete. Based on conversations with the 
community these patches are intended to lay the groundwork for feature 
completion and collaboration within the RISC-V community.In version 1 of 
this patch submission I neglected to indicate that these patches are 
largely based off the work of Juzhe Zhong 
(juzhe.zhong@rivai.ai<mailto:juzhe.zhong@rivai.ai>) of RiVAI. More 
specifically the rvv-next branch 
at:https://github.com/riscv-collab/riscv-gcc.git 
<https://github.com/riscv-collab/riscv-gcc.git>is the foundation of this 
patch set. I want to publicly apologize to Juzhe and RiVIA for not 
attributing their work visibly and publicly.As discussed on this list, 
if these patches are approved they will be merged into a 
"auto-vectorization" branch once gcc-13 branches for release.There are 
two known issues related to crashes (assert failures) associated with 
tree vectorization; one of which I have sent a patch for and have 
received feedback.

Changes in v2

- Updated ChangeLog entry to include RiVAI contributions

- Fixed ChangeLog email formatting

- Fixed gnu formatting issues in the code