doc/guide/src/CompileTimeOptions.adoc

   1 CompileTimeOptions
   2 ==================
   3
   4 MLton's compile-time options control the name of the output file, the
   5 verbosity of compile-time messages, and whether or not certain
   6 optimizations are performed.  They also can specify which intermediate
   7 files are saved and can stop the compilation process early, at some
   8 intermediate pass, in which case compilation can be resumed by passing
   9 the generated files to MLton.  MLton uses the input file suffix to
  10 determine the type of input program.  The possibilities are `.c`,
  11 `.mlb`, `.o`, `.s`, and `.sml`.
  12
  13 With no arguments, MLton prints the version number and exits.  For a
  14 usage message, run MLton with an invalid switch, e.g.  `mlton -z`.  In
  15 the explanation below and in the usage message, for flags that take a
  16 number of choices (e.g. `{true|false}`), the first value listed is the
  17 default.
  18
  19
  20 == Options ==
  21
  22 * ++-align __n__++
  23 +
  24 Aligns object in memory by the specified alignment (+4+ or +8+).
  25 The default varies depending on architecture.
  26
  27 * ++-as-opt __option__++
  28 +
  29 Pass _option_ to `gcc` when compiling assembler code.  If you wish to
  30 pass an option to the assembler, you must use `gcc`'s `-Wa,` syntax.
  31
  32 * ++-cc-opt __option__++
  33 +
  34 Pass _option_ to `gcc` when compiling C code.
  35
  36 * ++-codegen {native|amd64|c|llvm|x86}++
  37 +
  38 Generate native object code via amd64 assembly, C code, LLVM code, or
  39 x86 code or C code.  With `-codegen native` (`-codegen amd64` or
  40 `-codegen x86`), MLton typically compiles more quickly and generates
  41 better code.
  42
  43 * ++-const __name__ __value__++
  44 +
  45 Set the value of a compile-time constant.  Here is a list of
  46 available constants, their default values, and what they control.
  47 +
  48 ** ++Exn.keepHistory {false|true}++
  49 +
  50 Enable `MLton.Exn.history`.  See <:MLtonExn:> for details.  There is a
  51 performance cost to setting this to `true`, both in memory usage of
  52 exceptions and in run time, because of additional work that must be
  53 performed at each exception construction, raise, and handle.
  54
  55 * ++-default-ann __ann__++
  56 +
  57 Specify default <:MLBasisAnnotations:ML Basis annotations>.  For
  58 example, `-default-ann 'warnUnused true'` causes unused variable
  59 warnings to be enabled by default.  A default is overridden by the
  60 corresponding annotation in an ML Basis file.
  61
  62 * ++-default-type __type__++
  63 +
  64 Specify the default binding for a primitive type.  For example,
  65 `-default-type word64` causes the top-level type `word` and the
  66 top-level structure `Word` in the <:BasisLibrary:Basis Library> to be
  67 equal to `Word64.word` and `Word64:WORD`, respectively.  Similarly,
  68 `-default-type intinf` causes the top-level type `int` and the
  69 top-level structure `Int` in the <:BasisLibrary:Basis Library> to be
  70 equal to `IntInf.int` and `IntInf:INTEGER`, respectively.
  71
  72 * ++-disable-ann __ann__++
  73 +
  74 Ignore the specified <:MLBasisAnnotations:ML Basis annotation> in
  75 every ML Basis file.  For example, to see _all_ match and unused
  76 warnings, compile with
  77 +
  78 ----
  79 -default-ann 'warnUnused true'
  80 -disable-ann forceUsed
  81 -disable-ann nonexhaustiveMatch
  82 -disable-ann redundantMatch
  83 -disable-ann warnUnused
  84 ----
  85
  86 * ++-export-header __file__++
  87 +
  88 Write C prototypes to _file_ for all of the functions in the program
  89 <:CallingFromCToSML:exported from SML to C>.
  90
  91 * ++-ieee-fp {false|true}++
  92 +
  93 Cause the x86 native code generator to be pedantic about following the
  94 IEEE floating point standard.  By default, it is not, because of the
  95 performance cost.  This only has an effect with `-codegen x86`.
  96
  97 * ++-inline __n__++
  98 +
  99 Set the inlining threshold used in the optimizer.  The threshold is an
 100 approximate measure of code size of a procedure.  The default is
 101 `320`.
 102
 103 * ++-keep {g|o}++
 104 +
 105 Save intermediate files.  If no `-keep` argument is given, then only
 106 the output file is saved.
 107 +
 108 [cols="^25%,<75%"]
 109 |====
 110 | `g` | generated `.c` and `.s` files passed to `gcc` and generated `.ll` files passed to `llvm-as`
 111 | `o` | object (`.o`) files
 112 |====
 113
 114 * ++-link-opt __option__++
 115 +
 116 Pass _option_ to `gcc` when linking.  You can use this to specify
 117 library search paths, e.g. `-link-opt -Lpath`, and libraries to link
 118 with, e.g., `-link-opt -lfoo`, or even both at the same time,
 119 e.g. `-link-opt '-Lpath -lfoo'`.  If you wish to pass an option to the
 120 linker, you must use `gcc`'s `-Wl,` syntax, e.g.,
 121 `-link-opt '-Wl,--export-dynamic'`.
 122
 123 * ++-llvm-as-opt __option__++
 124 +
 125 Pass _option_ to `llvm-as` when assembling (`.ll` to `.bc`) LLVM code.
 126
 127 * ++-llvm-llc-opt __option__++
 128 +
 129 Pass _option_ to `llc` when compiling (`.bc` to `.o`) LLVM code.
 130
 131 * ++-llvm-opt-opt __option__++
 132 +
 133 Pass _option_ to `opt` when optimizing (`.bc` to `.bc`) LLVM code.
 134
 135 * ++-mlb-path-map __file__++
 136 +
 137 Use _file_ as an <:MLBasisPathMap:ML Basis path map> to define
 138 additional MLB path variables.  Multiple uses of `-mlb-path-map` and
 139 `-mlb-path-var` are allowed, with variable definitions in later path
 140 maps taking precedence over earlier ones.
 141
 142 * ++-mlb-path-var __name__ __value__++
 143 +
 144 Define an additional MLB path variable.  Multiple uses of
 145 `-mlb-path-map` and `-mlb-path-var` are allowed, with variable
 146 definitions in later path maps taking precedence over earlier ones.
 147
 148 * ++-output __file__++
 149 +
 150 Specify the name of the final output file. The default name is the
 151 input file name with its suffix removed and an appropriate, possibly
 152 empty, suffix added.
 153
 154 * ++-profile {no|alloc|count|time}++
 155 +
 156 Produce an executable that gathers <:Profiling: profiling> data.  When
 157 such an executable is run, it produces an `mlmon.out` file.
 158
 159 * ++-profile-branch {false|true}++
 160 +
 161 If true, the profiler will separately gather profiling data for each
 162 branch of a function definition, `case` expression, and `if`
 163 expression.
 164
 165 * ++-profile-stack {false|true}++
 166 +
 167 If `true`, the executable will gather profiling data for all functions
 168 on the stack, not just the currently executing function.  See
 169 <:ProfilingTheStack:>.
 170
 171 * ++-profile-val {false|true}++
 172 +
 173 If `true`, the profiler will separately gather profiling data for each
 174 (expansive) `val` declaration.
 175
 176 * ++-runtime __arg__++
 177 +
 178 Pass argument to the runtime system via `@MLton`.  See
 179 <:RunTimeOptions:>.  The argument will be processed before other
 180 `@MLton` command line switches.  Multiple uses of `-runtime` are
 181 allowed, and will pass all the arguments in order.  If the same
 182 runtime switch occurs more than once, then the last setting will take
 183 effect.  There is no need to supply the leading `@MLton` or the
 184 trailing `--`; these will be supplied automatically.
 185 +
 186 An argument to `-runtime` may contain spaces, which will cause the
 187 argument to be treated as a sequence of words by the runtime.  For
 188 example the command line:
 189 +
 190 ----
 191 mlton -runtime 'ram-slop 0.4' foo.sml
 192 ----
 193 +
 194 will cause `foo` to run as if it had been called like:
 195 +
 196 ----
 197 foo @MLton ram-slop 0.4 --
 198 ----
 199 +
 200 An executable created with `-runtime stop` doesn't process any
 201 `@MLton` arguments.  This is useful to create an executable, e.g.,
 202 `echo`, that must treat `@MLton` like any other command-line argument.
 203 +
 204 ----
 205 % mlton -runtime stop echo.sml
 206 % echo @MLton --
 207 @MLton --
 208 ----
 209
 210 * ++-show-basis __file__++
 211 +
 212 Pretty print to _file_ the basis defined by the input program.  See
 213 <:ShowBasis:>.
 214
 215 * ++-show-def-use __file__++
 216 +
 217 Output def-use information to _file_.  Each identifier that is defined
 218 appears on a line, followed on subsequent lines by the position of
 219 each use.
 220
 221 * ++-stop {f|g|o|tc}++
 222 +
 223 Specify when to stop.
 224 +
 225 [cols="^25%,<75%"]
 226 |====
 227 | `f` | list of files on stdout (only makes sense when input is `foo.mlb`)
 228 | `g` | generated `.c` and `.s` files
 229 | `o` | object (`.o`) files
 230 | `tc` | after type checking
 231 |====
 232 +
 233 If you compile with `-stop g` or `-stop o`, you can resume compilation
 234 by running MLton on the generated `.c` and `.s` or `.o` files.
 235
 236 * ++-target {self|__...__}++
 237 +
 238 Generate an executable that runs on the specified platform.  The
 239 default is `self`, which means to compile for the machine that MLton
 240 is running on.  To use any other target, you must first install a
 241 <:CrossCompiling: cross compiler>.
 242
 243 * ++-target-as-opt __target__ __option__++
 244 +
 245 Like `-as-opt`, this passes _option_ to `gcc` when compliling
 246 assembler code, except it only passes _option_ when the target
 247 architecture, operating system, or arch-os pair is _target_.
 248
 249 * ++-target-cc-opt __target__ __option__++
 250 +
 251 Like `-cc-opt`, this passes _option_ to `gcc` when compiling C code,
 252 except it only passes _option_ when the target architecture, operating
 253 system, or arch-os pair is _target_.
 254
 255 * ++-target-link-opt __target__ __option__++
 256 +
 257 Like `-link-opt`, this passes _option_ to `gcc` when linking, except
 258 it only passes _option_ when the target architecture, operating
 259 system, or arch-os pair is _target_.
 260
 261 * ++-verbose {0|1|2|3}++
 262 +
 263 How verbose to be about what passes are running.  The default is `0`.
 264 +
 265 [cols="^25%,<75%"]
 266 |====
 267 | `0` | silent
 268 | `1` | calls to compiler, assembler, and linker
 269 | `2` | 1, plus intermediate compiler passes
 270 | `3` | 2, plus some data structure sizes
 271 |====