1use crate::cdsl::settings::{SettingGroup, SettingGroupBuilder};
2
3pub(crate) fn define() -> SettingGroup {
4 let mut settings = SettingGroupBuilder::new("shared");
5
6 settings.add_bool(
7 "regalloc_checker",
8 "Enable the symbolic checker for register allocation.",
9 r#"
10 This performs a verification that the register allocator preserves
11 equivalent dataflow with respect to the original (pre-regalloc)
12 program. This analysis is somewhat expensive. However, if it succeeds,
13 it provides independent evidence (by a carefully-reviewed, from-first-principles
14 analysis) that no regalloc bugs were triggered for the particular compilations
15 performed. This is a valuable assurance to have as regalloc bugs can be
16 very dangerous and difficult to debug.
17 "#,
18 false,
19 );
20
21 settings.add_bool(
22 "regalloc_verbose_logs",
23 "Enable verbose debug logs for regalloc2.",
24 r#"
25 This adds extra logging for regalloc2 output, that is quite valuable to understand
26 decisions taken by the register allocator as well as debugging it. It is disabled by
27 default, as it can cause many log calls which can slow down compilation by a large
28 amount.
29 "#,
30 false,
31 );
32
33 settings.add_enum(
34 "regalloc_algorithm",
35 "Algorithm to use in register allocator.",
36 r#"
37 Supported options:
38
39 - `backtracking`: A backtracking allocator with range splitting; more expensive
40 but generates better code.
41 - `single_pass`: A single-pass algorithm that yields quick compilation but
42 results in code with more register spills and moves.
43 "#,
44 vec!["backtracking", "single_pass"],
45 );
46
47 settings.add_enum(
48 "opt_level",
49 "Optimization level for generated code.",
50 r#"
51 Supported levels:
52
53 - `none`: Minimise compile time by disabling most optimizations.
54 - `speed`: Generate the fastest possible code
55 - `speed_and_size`: like "speed", but also perform transformations aimed at reducing code size.
56 "#,
57 vec!["none", "speed", "speed_and_size"],
58 );
59
60 settings.add_bool(
61 "enable_alias_analysis",
62 "Do redundant-load optimizations with alias analysis.",
63 r#"
64 This enables the use of a simple alias analysis to optimize away redundant loads.
65 Only effective when `opt_level` is `speed` or `speed_and_size`.
66 "#,
67 true,
68 );
69
70 settings.add_bool(
71 "enable_verifier",
72 "Run the Cranelift IR verifier at strategic times during compilation.",
73 r#"
74 This makes compilation slower but catches many bugs. The verifier is always enabled by
75 default, which is useful during development.
76 "#,
77 true,
78 );
79
80 settings.add_bool(
81 "enable_pcc",
82 "Enable proof-carrying code translation validation.",
83 r#"
84 This adds a proof-carrying-code mode. Proof-carrying code (PCC) is a strategy to verify
85 that the compiler preserves certain properties or invariants in the compiled code.
86 For example, a frontend that translates WebAssembly to CLIF can embed PCC facts in
87 the CLIF, and Cranelift will verify that the final machine code satisfies the stated
88 facts at each intermediate computed value. Loads and stores can be marked as "checked"
89 and their memory effects can be verified as safe.
90 "#,
91 false,
92 );
93
94 settings.add_bool(
98 "is_pic",
99 "Enable Position-Independent Code generation.",
100 "",
101 false,
102 );
103
104 settings.add_bool(
105 "use_colocated_libcalls",
106 "Use colocated libcalls.",
107 r#"
108 Generate code that assumes that libcalls can be declared "colocated",
109 meaning they will be defined along with the current function, such that
110 they can use more efficient addressing.
111 "#,
112 false,
113 );
114
115 settings.add_bool(
116 "enable_float",
117 "Enable the use of floating-point instructions.",
118 r#"
119 Disabling use of floating-point instructions is not yet implemented.
120 "#,
121 true,
122 );
123
124 settings.add_bool(
125 "enable_nan_canonicalization",
126 "Enable NaN canonicalization.",
127 r#"
128 This replaces NaNs with a single canonical value, for users requiring
129 entirely deterministic WebAssembly computation. This is not required
130 by the WebAssembly spec, so it is not enabled by default.
131 "#,
132 false,
133 );
134
135 settings.add_bool(
136 "enable_pinned_reg",
137 "Enable the use of the pinned register.",
138 r#"
139 This register is excluded from register allocation, and is completely under the control of
140 the end-user. It is possible to read it via the get_pinned_reg instruction, and to set it
141 with the set_pinned_reg instruction.
142 "#,
143 false,
144 );
145
146 settings.add_bool(
147 "enable_atomics",
148 "Enable the use of atomic instructions",
149 "",
150 true,
151 );
152
153 settings.add_bool(
154 "enable_safepoints",
155 "Enable safepoint instruction insertions.",
156 r#"
157 This will allow the emit_stack_maps() function to insert the safepoint
158 instruction on top of calls and interrupt traps in order to display the
159 live reference values at that point in the program.
160 "#,
161 false,
162 );
163
164 settings.add_enum(
165 "tls_model",
166 "Defines the model used to perform TLS accesses.",
167 "",
168 vec!["none", "elf_gd", "macho", "coff"],
169 );
170
171 settings.add_enum(
172 "stack_switch_model",
173 "Defines the model used to performing stack switching.",
174 r#"
175 This determines the compilation of `stack_switch` instructions. If
176 set to `basic`, we simply save all registers, update stack pointer
177 and frame pointer (if needed), and jump to the target IP.
178 If set to `update_windows_tib`, we *additionally* update information
179 about the active stack in Windows' Thread Information Block.
180 "#,
181 vec!["none", "basic", "update_windows_tib"],
182 );
183
184 settings.add_enum(
185 "libcall_call_conv",
186 "Defines the calling convention to use for LibCalls call expansion.",
187 r#"
188 This may be different from the ISA default calling convention.
189
190 The default value is to use the same calling convention as the ISA
191 default calling convention.
192
193 This list should be kept in sync with the list of calling
194 conventions available in isa/call_conv.rs.
195 "#,
196 vec![
197 "isa_default",
198 "fast",
199 "cold",
200 "system_v",
201 "windows_fastcall",
202 "apple_aarch64",
203 "probestack",
204 ],
205 );
206
207 settings.add_bool(
208 "enable_llvm_abi_extensions",
209 "Enable various ABI extensions defined by LLVM's behavior.",
210 r#"
211 In some cases, LLVM's implementation of an ABI (calling convention)
212 goes beyond a standard and supports additional argument types or
213 behavior. This option instructs Cranelift codegen to follow LLVM's
214 behavior where applicable.
215
216 Currently, this applies only to Windows Fastcall on x86-64, and
217 allows an `i128` argument to be spread across two 64-bit integer
218 registers. The Fastcall implementation otherwise does not support
219 `i128` arguments, and will panic if they are present and this
220 option is not set.
221 "#,
222 false,
223 );
224
225 settings.add_bool(
226 "enable_multi_ret_implicit_sret",
227 "Enable support for sret arg introduction when there are too many ret vals.",
228 r#"
229 When there are more returns than available return registers, the
230 return value has to be returned through the introduction of a
231 return area pointer. Normally this return area pointer has to be
232 introduced as `ArgumentPurpose::StructReturn` parameter, but for
233 backward compatibility reasons Cranelift also supports implicitly
234 introducing this parameter and writing the return values through it.
235
236 **This option currently does not conform to platform ABIs and the
237 used ABI should not be assumed to remain the same between Cranelift
238 versions.**
239
240 This option is **deprecated** and will be removed in the future.
241
242 Because of the above issues, and complexities of native ABI support
243 for the concept in general, Cranelift's support for multiple return
244 values may also be removed in the future (#9510). For the most
245 robust solution, it is recommended to build a convention on top of
246 Cranelift's primitives for passing multiple return values, for
247 example by allocating a stackslot in the caller, passing it as an
248 explicit StructReturn argument, storing return values in the callee,
249 and loading results in the caller.
250 "#,
251 false,
252 );
253
254 settings.add_bool(
255 "unwind_info",
256 "Generate unwind information.",
257 r#"
258 This increases metadata size and compile time, but allows for the
259 debugger to trace frames, is needed for GC tracing that relies on
260 libunwind (such as in Wasmtime), and is unconditionally needed on
261 certain platforms (such as Windows) that must always be able to unwind.
262 "#,
263 true,
264 );
265
266 settings.add_bool(
267 "preserve_frame_pointers",
268 "Preserve frame pointers",
269 r#"
270 Preserving frame pointers -- even inside leaf functions -- makes it
271 easy to capture the stack of a running program, without requiring any
272 side tables or metadata (like `.eh_frame` sections). Many sampling
273 profilers and similar tools walk frame pointers to capture stacks.
274 Enabling this option will play nice with those tools.
275 "#,
276 false,
277 );
278
279 settings.add_bool(
280 "machine_code_cfg_info",
281 "Generate CFG metadata for machine code.",
282 r#"
283 This increases metadata size and compile time, but allows for the
284 embedder to more easily post-process or analyze the generated
285 machine code. It provides code offsets for the start of each
286 basic block in the generated machine code, and a list of CFG
287 edges (with blocks identified by start offsets) between them.
288 This is useful for, e.g., machine-code analyses that verify certain
289 properties of the generated code.
290 "#,
291 false,
292 );
293
294 settings.add_bool(
297 "enable_probestack",
298 "Enable the use of stack probes for supported calling conventions.",
299 "",
300 false,
301 );
302
303 settings.add_num(
304 "probestack_size_log2",
305 "The log2 of the size of the stack guard region.",
306 r#"
307 Stack frames larger than this size will have stack overflow checked
308 by calling the probestack function.
309
310 The default is 12, which translates to a size of 4096.
311 "#,
312 12,
313 );
314
315 settings.add_enum(
316 "probestack_strategy",
317 "Controls what kinds of stack probes are emitted.",
318 r#"
319 Supported strategies:
320
321 - `outline`: Always emits stack probes as calls to a probe stack function.
322 - `inline`: Always emits inline stack probes.
323 "#,
324 vec!["outline", "inline"],
325 );
326
327 settings.add_bool(
330 "enable_jump_tables",
331 "Enable the use of jump tables in generated machine code.",
332 "",
333 true,
334 );
335
336 settings.add_bool(
339 "enable_heap_access_spectre_mitigation",
340 "Enable Spectre mitigation on heap bounds checks.",
341 r#"
342 This is a no-op for any heap that needs no bounds checks; e.g.,
343 if the limit is static and the guard region is large enough that
344 the index cannot reach past it.
345
346 This option is enabled by default because it is highly
347 recommended for secure sandboxing. The embedder should consider
348 the security implications carefully before disabling this option.
349 "#,
350 true,
351 );
352
353 settings.add_bool(
354 "enable_table_access_spectre_mitigation",
355 "Enable Spectre mitigation on table bounds checks.",
356 r#"
357 This option uses a conditional move to ensure that when a table
358 access index is bounds-checked and a conditional branch is used
359 for the out-of-bounds case, a misspeculation of that conditional
360 branch (falsely predicted in-bounds) will select an in-bounds
361 index to load on the speculative path.
362
363 This option is enabled by default because it is highly
364 recommended for secure sandboxing. The embedder should consider
365 the security implications carefully before disabling this option.
366 "#,
367 true,
368 );
369
370 settings.add_bool(
371 "enable_incremental_compilation_cache_checks",
372 "Enable additional checks for debugging the incremental compilation cache.",
373 r#"
374 Enables additional checks that are useful during development of the incremental
375 compilation cache. This should be mostly useful for Cranelift hackers, as well as for
376 helping to debug false incremental cache positives for embedders.
377
378 This option is disabled by default and requires enabling the "incremental-cache" Cargo
379 feature in cranelift-codegen.
380 "#,
381 false,
382 );
383
384 settings.add_num(
385 "bb_padding_log2_minus_one",
386 "The log2 of the size to insert dummy padding between basic blocks",
387 r#"
388 This is a debugging option for stressing various cases during code
389 generation without requiring large functions. This will insert
390 0-byte padding between basic blocks of the specified size.
391
392 The amount of padding inserted two raised to the power of this value
393 minus one. If this value is 0 then no padding is inserted.
394
395 The default for this option is 0 to insert no padding as it's only
396 intended for testing and development.
397 "#,
398 0,
399 );
400
401 settings.build()
404}