[CIR] Provide syntax highlighting support of clang ir for vim/nvim users (#1854)

Hi there, I'm opening the PR to add syntax highlighting support for vim
and neovim users.

The PR borrows a lot from MLIR but also add
- Dedicated CIR types like bytes
- Dedicated CIR keywords(?!) like coroutine, resume, suspend, etc etc.
- Blanket operation highlighting for CIR operations (No need to edit
syntax/cir.vim again for new operations)

Below is the before and after of applying syntax highlighting. 


Before:
<img width="1532" height="1003" alt="Screenshot 2025-08-22 at 3 30
44 PM"
src="https://github.com/user-attachments/assets/b94f8965-99db-41b0-a3e2-c004b4dfd6b8"
/>


After:
<img width="1532" height="1003" alt="Screenshot 2025-08-22 at 3 30
21 PM"
src="https://github.com/user-attachments/assets/e25448de-8dc3-4df3-88e3-35143a06c53a"
/>

Author: badumbatish

mlir/utils/vim/ftdetect/cir.vim

@@ -0,0 +1 @@
+au BufRead,BufNewFile *.cir set filetype=cir

mlir/utils/vim/syntax/cir.vim

@@ -0,0 +1,128 @@
+" Vim syntax file
+" Language:   cir
+" Maintainer: The CIR team
+" Version:      $Revision$
+" Some parts adapted from the LLVM and MLIR vim syntax file.
+
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax")
+  finish
+endif
+
+syn case match
+
+" Types.
+"
+syn keyword mlirType index
+syn match mlirType /\<f\d\+\>/
+syn match mlirType /\<bf\d\+\>/
+" Signless integer types.
+syn match mlirType /\<i\d\+\>/
+" Unsigned integer types.
+syn match mlirType /\<ui\d\+\>/
+" Signed integer types.
+syn match mlirType /\<si\d\+\>/
+
+" Elemental types inside memref, tensor, or vector types.
+syn match mlirType /x\s*\zs\(bf16|f16\|f32\|f64\|i\d\+\|ui\d\+\|si\d\+\)/
+
+" Shaped types.
+syn match mlirType /\<memref\ze\s*<.*>/
+syn match mlirType /\<tensor\ze\s*<.*>/
+syn match mlirType /\<vector\ze\s*<.*>/
+
+" vector types inside memref or tensor.
+syn match mlirType /x\s*\zsvector/
+
+" Misc syntax.
+
+syn match   mlirNumber /-\?\<\d\+\>/
+" Match numbers even in shaped types.
+syn match   mlirNumber /-\?\<\d\+\ze\s*x/
+syn match   mlirNumber /x\s*\zs-\?\d\+\ze\s*x/
+
+syn match   mlirFloat  /-\?\<\d\+\.\d*\(e[+-]\d\+\)\?\>/
+syn match   mlirFloat  /\<0x\x\+\>/
+syn keyword mlirBoolean true false
+" Spell checking is enabled only in comments by default.
+syn match   mlirComment /\/\/.*$/ contains=@Spell
+syn region  mlirString start=/"/ skip=/\\"/ end=/"/
+syn match   mlirLabel /[-a-zA-Z$._][-a-zA-Z$._0-9]*:/
+" Prefixed identifiers usually used for ssa values and symbols.
+syn match   mlirIdentifier /[%@][a-zA-Z$._-][a-zA-Z0-9$._-]*/
+syn match   mlirIdentifier /[%@]\d\+\>/
+" Prefixed identifiers usually used for blocks.
+syn match   mlirBlockIdentifier /\^[a-zA-Z$._-][a-zA-Z0-9$._-]*/
+syn match   mlirBlockIdentifier /\^\d\+\>/
+" Prefixed identifiers usually used for types.
+syn match   mlirTypeIdentifier /![a-zA-Z$._-][a-zA-Z0-9$._-]*/
+syn match   mlirTypeIdentifier /!\d\+\>/
+" Prefixed identifiers usually used for attribute aliases and result numbers.
+syn match   mlirAttrIdentifier /#[a-zA-Z$._-][a-zA-Z0-9$._-]*/
+syn match   mlirAttrIdentifier /#\d\+\>/
+
+" Syntax-highlight lit test commands and bug numbers.
+" Old highlighting version of MLIR is faulty, any misamount of whitespace before or after on a line
+" will not highlight the special comments anymore.
+syn match mlirSpecialComment /^\s*\/\/\s*RUN:.*$/
+syn match mlirSpecialComment /^\s*\/\/\s*\(CHECK\|CIR\|MLIR\|LLVM\|OGCG\):.*$/
+syn match mlirSpecialComment /^\s*\/\/\s*\(CHECK\|CIR\|MLIR\|LLVM\|OGCG\)-\(NEXT\|NOT\|DAG\|SAME\|LABEL\):.*$/
+syn match mlirSpecialComment /^\s*\/\/\s*expected-error.*$/
+syn match mlirSpecialComment /^\s*\/\/\s*expected-remark.*$/
+syn match mlirSpecialComment /^\s*;\s*XFAIL:.*$/
+syn match mlirSpecialComment /^\s*\/\/\s*PR\d*\s*$/
+syn match mlirSpecialComment /^\s*\/\/\s*REQUIRES:.*$/
+
+"""""""""""" CIR SECTION """"""""""""
+" CIR blanket operations
+syn match cirOps /\vcir(\.\w+)+/
+
+syn keyword cirKeyword
+      \ module attributes
+      \ from to cond body step
+      \ align alignment init
+      \ cond exception
+      \ null
+      \ coroutine suspend resume cleanup
+      \ class union struct
+      \ do while
+      \ if then else
+      \ nsw nuw
+      \ constant
+      \ equal default anyof
+      \ internal external available_externally private linkonce linkonce_odr 
+      \ weak weak_odr extern_weak common cir_private
+
+
+syn keyword cirType bytes
+
+
+if version >= 508 || !exists("did_c_syn_inits")
+  if version < 508
+    let did_c_syn_inits = 1
+    command -nargs=+ HiLink hi link <args>
+  else
+    command -nargs=+ HiLink hi def link <args>
+  endif
+
+  HiLink mlirType Type
+  HiLink mlirNumber Number
+  HiLink mlirComment Comment
+  HiLink mlirString String
+  HiLink mlirLabel Label
+  HiLink mlirBoolean Boolean
+  HiLink mlirFloat Float
+  HiLink mlirSpecialComment SpecialComment
+  HiLink mlirIdentifier Identifier
+  HiLink mlirBlockIdentifier Label
+  HiLink mlirTypeIdentifier Type
+  HiLink mlirAttrIdentifier PreProc
+
+  HiLink cirType Type
+  HiLink cirOps Statement
+  HiLink cirKeyword Keyword
+  delcommand HiLink
+endif
+
+let b:current_syntax = "cir"