Cmm syntax

The GHC has three different syntaxes for Cmm:

Hand-writing syntax by GHC/Cmm/Parser.y (e.g. PrimOps.cmm)
Pretty-printing syntax by GHC/Cmm/Ppr.hs (as ghc --ddump-cmm)
Intermediate representation in GHC/Cmm.hs

To improve readability of Cmm files, this page shows the hand-writing syntax defined by GHC/Cmm/Parser.y.

See Code Generator and The Runtime System.
See also cmm-type.

Cmm hand-writing syntax

Following syntax was manually extracted from GHC/Cmm/Parser.y at commit 5618fc21.

cmm    →  {- empty -}
        | cmmtop cmm

cmmtop →  cmmproc
        | cmmdata
        | decl
        | 'CLOSURE' '(' NAME ',' NAME lits ')' ';'  

cmmdata →  'section' STRING '{' data_label statics '}'

data_label →  NAME ':'

statics →  {- empty -}
         | static statics
    
static →  type expr ';'
        | type ';'
        | 'bits8' '[' ']' STRING ';'
        | 'bits8' '[' INT ']' ';'
        | typenot8 '[' INT ']' ';'
        | 'CLOSURE' '(' NAME lits ')'

lits   →  {- empty -}
        | ',' expr lits

cmmproc →  info maybe_conv maybe_formals maybe_body

maybe_conv →  {- empty -}
            | 'return'

maybe_body →  ';'
            | '{' body '}'

info   →  NAME
        | 'INFO_TABLE' '(' NAME ',' INT ',' INT ',' INT ',' STRING ',' STRING ')'
        | 'INFO_TABLE_FUN' '(' NAME ',' INT ',' INT ',' INT ',' STRING ',' STRING ',' INT ',' INT ')'
        | 'INFO_TABLE_CONSTR' '(' NAME ',' INT ',' INT ',' INT ',' INT ',' STRING ',' STRING ')'
        | 'INFO_TABLE_SELECTOR' '(' NAME ',' INT ',' INT ',' STRING ',' STRING ')'
        | 'INFO_TABLE_RET' '(' NAME ',' INT ')'
        | 'INFO_TABLE_RET' '(' NAME ',' INT ',' formals0 ')'

body   →  {- empty -}
        | decl body
        | stmt body

decl   →  type names ';'
        | 'import' importNames ';'
        | 'export' names ';'

importNames →  importName
             | importName ',' importNames

importName →  NAME
            | 'CLOSURE' NAME
            | STRING NAME
        
names  →  NAME
        | NAME ',' names

stmt   →  ';'
        | NAME ':'
        | lreg '=' expr ';'
        | lreg '=' mem_ordering type '[' expr ']' ';'
        | mem_ordering type '[' expr ']' '=' expr ';'
        | type '[' expr ']' '=' expr ';'
        | foreign_results 'foreign' STRING foreignLabel '(' cmm_hint_exprs0 ')' safety opt_never_returns ';'
        | foreign_results 'prim' '%' NAME '(' exprs0 ')' ';'
        | NAME '(' exprs0 ')' ';'
        | 'switch' maybe_range expr '{' arms default '}'
        | 'goto' NAME ';'
        | 'return' '(' exprs0 ')' ';'
        | 'jump' expr vols ';'
        | 'jump' expr '(' exprs0 ')' ';'
        | 'jump' expr '(' exprs0 ')' '(' exprs0 ')' ';'
        | 'call' expr '(' exprs0 ')' ';'
        | '(' formals ')' '=' 'call' expr '(' exprs0 ')' ';'
        | 'if' bool_expr cond_likely 'goto' NAME
        | 'if' bool_expr cond_likely '{' body '}' else
        | 'push' '(' exprs0 ')' maybe_body
        | 'reserve' expr '=' lreg maybe_body
        | 'unwind' unwind_regs ';'

unwind_regs →  GLOBALREG '=' expr_or_unknown ',' unwind_regs
             | GLOBALREG '=' expr_or_unknown

mem_ordering →  'relaxed'
              | 'release'
              | 'acquire'
              | 'seq_cst'

expr_or_unknown →  'return'
                 | expr

foreignLabel →  NAME

opt_never_returns →  {- empty -}
                   | 'never' 'returns'

bool_expr →  bool_op
           | expr

bool_op →  bool_expr '&&' bool_expr
         | bool_expr '||' bool_expr
         | '!' bool_expr
         | '(' bool_op ')'

safety →  {- empty -}
        | STRING

vols   →  '[' ']'
        | '[' '*' ']'
        | '[' globals ']'

globals →  GLOBALREG
         | GLOBALREG ',' globals

maybe_range →  '[' INT '..' INT ']'
             | {- empty -}

arms   →  {- empty -}
        | arm arms

arm    →  'case' ints ':' arm_body

arm_body →  '{' body '}'
          | 'goto' NAME ';'

ints   →  INT
        | INT ',' ints

default →  'default' ':' '{' body '}'
         | {- empty -}

else   →  {- empty -}
        | 'else' '{' body '}'

cond_likely →  '(' 'likely' ':' 'True'  ')'
             | '(' 'likely' ':' 'False' ')'
             | {- empty -}

expr   →  expr '/' expr
        | expr '*' expr
        | expr '%' expr
        | expr '-' expr
        | expr '+' expr
        | expr '>>' expr
        | expr '<<' expr
        | expr '&' expr
        | expr '^' expr
        | expr '|' expr
        | expr '>=' expr
        | expr '>' expr
        | expr '<=' expr
        | expr '<' expr
        | expr '!=' expr
        | expr '==' expr
        | '~' expr
        | '-' expr
        | expr0 '`' NAME '`' expr0
        | expr0

expr0  →  INT   maybe_ty
        | FLOAT maybe_ty
        | STRING
        | reg
        | type dereference
        | '%' NAME '(' exprs0 ')'
        | '(' expr ')'

dereference →  '^' '[' expr ']'
             | '[' expr ']'

maybe_ty →  {- empty -}
          | '::' type

cmm_hint_exprs0 →  {- empty -}
                 | cmm_hint_exprs

cmm_hint_exprs →  cmm_hint_expr
                | cmm_hint_expr ',' cmm_hint_exprs

cmm_hint_expr →  expr
               | expr STRING

exprs0 →  {- empty -}
        | exprs

exprs  →  expr
        | expr ',' exprs

reg    →  NAME
        | GLOBALREG

foreign_results →  {- empty -}
                 | '(' foreign_formals ')' '='

foreign_formals →  foreign_formal
                 | foreign_formal ','
                 | foreign_formal ',' foreign_formals

foreign_formal →  local_lreg
                | STRING local_lreg

local_lreg →  NAME

lreg       →  NAME
           | GLOBALREG

maybe_formals →  {- empty -}
               | '(' formals0 ')'

formals0 →  {- empty -}
          | formals

formals  →  formal ','
          | formal
          | formal ',' formals

formal   →  type NAME

type   →  'bits8'
        | typenot8

typenot8 →  'bits16'
          | 'bits32'
          | 'bits64'
          | 'bits128'
          | 'bits256'
          | 'bits512'
          | 'float32'
          | 'float64'
          | 'gcptr'

See also GHC/Cmm/Lexer.x for lexical tokens. For instance:

GLOBALREG →  P@decimal
             R@decimal
             F@decimal
             D@decimal
             L@decimal
             Sp
             SpLim
             Hp
             HpLim
             CCCS
             CurrentTSO
             CurrentNursery
             HpAlloc
             BaseReg
             MachSp
             UnwindReturnReg

Built-in macros and primitives

Some built-in macros and primitives are defined for Cmm hand-writing syntax in GHC/Cmm/Parser.y.

Built-in expression macros (exprMacros):

  %ENTRY_CODE
  %INFO_PTR
  %STD_INFO
  %FUN_INFO
  %GET_ENTRY
  %GET_STD_INFO
  %GET_FUN_INFO
  %INFO_TYPE
  %INFO_PTRS
  %INFO_NPTRS

Built-in primitives (machOps):

  %add
  %sub
  %eq
  %ne
  %mul
  %mulmayoflo
  %neg
  %quot
  %rem
  %divu
  %modu

  %ge
  %le
  %gt
  %lt

  %geu
  %leu
  %gtu
  %ltu

  %and
  %or
  %xor
  %com
  %shl
  %shrl
  %shra

  %fadd
  %fsub
  %fneg
  %fmul
  %fquot

  %feq
  %fne
  %fge
  %fle
  %fgt
  %flt

  %lobits8
  %lobits16
  %lobits32
  %lobits64

  %zx16
  %zx32
  %zx64

  %sx16
  %sx32
  %sx64

  %f2f32
  %f2f64
  %f2i8
  %f2i16
  %f2i32
  %f2i64
  %i2f32
  %i2f64

Built-in callish primitives (callishMachOps):

  %pow64f
  %sin64f
  %cos64f
  %tan64f
  %sinh64f
  %cosh64f
  %tanh64f
  %asin64f
  %acos64f
  %atan64f
  %asinh64f
  %acosh64f
  %log64f
  %log1p64f
  %exp64f
  %expM164f
  %fabs64f
  %sqrt64f

  %pow32f
  %sin32f
  %cos32f
  %tan32f
  %sinh32f
  %cosh32f
  %tanh32f
  %asin32f
  %acos32f
  %atan32f
  %asinh32f
  %acosh32f
  %log32f
  %log1p32f
  %exp32f
  %expM132f
  %fabs32f
  %sqrt32f

  %read_barrier
  %write_barrier
  %memcpy
  %memset
  %memmove
  %memcmp

  %suspendThread
  %resumeThread

  %prefetch0
  %prefetch1
  %prefetch2
  %prefetch3

  %popcnt
  %pdep
  %pext
  %cmpxchg
  %xchg
  %load_relaxed
  %load_acquire
  %load_seqcst
  %store_release
  %store_seqcst

Built-in statement macros (stmtMacros):

  CCS_ALLOC
  ENTER_CCS_THUNK
  CLOSE_NURSERY
  OPEN_NURSERY
  HP_CHK_GEN
  STK_CHK_GEN
  STK_CHK_GEN_N
  LOAD_THREAD_STATE
  SAVE_THREAD_STATE
  SAVE_REGS
  RESTORE_REGS
  PUSH_ARG_REGS
  POP_ARG_REGS
  LDV_ENTER
  LDV_RECORD_CREATE
  PUSH_UPD_FRAME
  SET_HDR
  TICK_ALLOC_PRIM
  TICK_ALLOC_PAP
  TICK_ALLOC_UP_THK
  UPD_BH_UPDATABLE

C-preprocessor macros

There are also C-preprocessor level macros, such as ccall, I64, Sp(n), LOAD_INFO, ENTER(x), and MAYBE_GC.

Those macros are defined in includes/Cmm.h.

Comments

Please register or sign in to add a comment.

cmm syntax

Cmm syntax

Cmm hand-writing syntax

Built-in macros and primitives

C-preprocessor macros

Comments