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(
84 "is_pic",
85 "Enable Position-Independent Code generation.",
86 "",
87 false,
88 );
89
90 settings.add_bool(
91 "use_colocated_libcalls",
92 "Use colocated libcalls.",
93 r#"
94 Generate code that assumes that libcalls can be declared "colocated",
95 meaning they will be defined along with the current function, such that
96 they can use more efficient addressing.
97 "#,
98 false,
99 );
100
101 settings.add_bool(
102 "enable_nan_canonicalization",
103 "Enable NaN canonicalization.",
104 r#"
105 This replaces NaNs with a single canonical value, for users requiring
106 entirely deterministic WebAssembly computation. This is not required
107 by the WebAssembly spec, so it is not enabled by default.
108 "#,
109 false,
110 );
111
112 settings.add_bool(
113 "enable_pinned_reg",
114 "Enable the use of the pinned register.",
115 r#"
116 This register is excluded from register allocation, and is completely under the control of
117 the end-user. It is possible to read it via the get_pinned_reg instruction, and to set it
118 with the set_pinned_reg instruction.
119 "#,
120 false,
121 );
122
123 settings.add_enum(
124 "tls_model",
125 "Defines the model used to perform TLS accesses.",
126 "",
127 vec!["none", "elf_gd", "macho", "coff"],
128 );
129
130 settings.add_enum(
131 "stack_switch_model",
132 "Defines the model used to performing stack switching.",
133 r#"
134 This determines the compilation of `stack_switch` instructions. If
135 set to `basic`, we simply save all registers, update stack pointer
136 and frame pointer (if needed), and jump to the target IP.
137 If set to `update_windows_tib`, we *additionally* update information
138 about the active stack in Windows' Thread Information Block.
139 "#,
140 vec!["none", "basic", "update_windows_tib"],
141 );
142
143 settings.add_enum(
144 "libcall_call_conv",
145 "Defines the calling convention to use for LibCalls call expansion.",
146 r#"
147 This may be different from the ISA default calling convention.
148
149 The default value is to use the same calling convention as the ISA
150 default calling convention.
151
152 This list should be kept in sync with the list of calling
153 conventions available in isa/call_conv.rs.
154 "#,
155 vec![
156 "isa_default",
157 "fast",
158 "system_v",
159 "windows_fastcall",
160 "apple_aarch64",
161 "probestack",
162 "preserve_all",
163 ],
164 );
165
166 settings.add_bool(
167 "enable_llvm_abi_extensions",
168 "Enable various ABI extensions defined by LLVM's behavior.",
169 r#"
170 In some cases, LLVM's implementation of an ABI (calling convention)
171 goes beyond a standard and supports additional argument types or
172 behavior. This option instructs Cranelift codegen to follow LLVM's
173 behavior where applicable.
174
175 Currently, this applies only to Windows Fastcall on x86-64, and
176 allows an `i128` argument to be spread across two 64-bit integer
177 registers. The Fastcall implementation otherwise does not support
178 `i128` arguments, and will panic if they are present and this
179 option is not set.
180 "#,
181 false,
182 );
183
184 settings.add_bool(
185 "enable_multi_ret_implicit_sret",
186 "Enable support for sret arg introduction when there are too many ret vals.",
187 r#"
188 When there are more returns than available return registers, the
189 return value has to be returned through the introduction of a
190 return area pointer. Normally this return area pointer has to be
191 introduced as `ArgumentPurpose::StructReturn` parameter, but for
192 backward compatibility reasons Cranelift also supports implicitly
193 introducing this parameter and writing the return values through it.
194
195 **This option currently does not conform to platform ABIs and the
196 used ABI should not be assumed to remain the same between Cranelift
197 versions.**
198
199 This option is **deprecated** and will be removed in the future.
200
201 Because of the above issues, and complexities of native ABI support
202 for the concept in general, Cranelift's support for multiple return
203 values may also be removed in the future (#9510). For the most
204 robust solution, it is recommended to build a convention on top of
205 Cranelift's primitives for passing multiple return values, for
206 example by allocating a stackslot in the caller, passing it as an
207 explicit StructReturn argument, storing return values in the callee,
208 and loading results in the caller.
209 "#,
210 false,
211 );
212
213 settings.add_bool(
214 "unwind_info",
215 "Generate unwind information.",
216 r#"
217 This increases metadata size and compile time, but allows for the
218 debugger to trace frames, is needed for GC tracing that relies on
219 libunwind (such as in Wasmtime), and is unconditionally needed on
220 certain platforms (such as Windows) that must always be able to unwind.
221 "#,
222 true,
223 );
224
225 settings.add_bool(
226 "preserve_frame_pointers",
227 "Preserve frame pointers",
228 r#"
229 Preserving frame pointers -- even inside leaf functions -- makes it
230 easy to capture the stack of a running program, without requiring any
231 side tables or metadata (like `.eh_frame` sections). Many sampling
232 profilers and similar tools walk frame pointers to capture stacks.
233 Enabling this option will play nice with those tools.
234 "#,
235 false,
236 );
237
238 settings.add_bool(
239 "machine_code_cfg_info",
240 "Generate CFG metadata for machine code.",
241 r#"
242 This increases metadata size and compile time, but allows for the
243 embedder to more easily post-process or analyze the generated
244 machine code. It provides code offsets for the start of each
245 basic block in the generated machine code, and a list of CFG
246 edges (with blocks identified by start offsets) between them.
247 This is useful for, e.g., machine-code analyses that verify certain
248 properties of the generated code.
249 "#,
250 false,
251 );
252
253 settings.add_bool(
256 "enable_probestack",
257 "Enable the use of stack probes for supported calling conventions.",
258 "",
259 false,
260 );
261
262 settings.add_num(
263 "probestack_size_log2",
264 "The log2 of the size of the stack guard region.",
265 r#"
266 Stack frames larger than this size will have stack overflow checked
267 by calling the probestack function.
268
269 The default is 12, which translates to a size of 4096.
270 "#,
271 12,
272 );
273
274 settings.add_enum(
275 "probestack_strategy",
276 "Controls what kinds of stack probes are emitted.",
277 r#"
278 Supported strategies:
279
280 - `outline`: Always emits stack probes as calls to a probe stack function.
281 - `inline`: Always emits inline stack probes.
282 "#,
283 vec!["outline", "inline"],
284 );
285
286 settings.add_bool(
290 "enable_heap_access_spectre_mitigation",
291 "Enable Spectre mitigation on heap bounds checks.",
292 r#"
293 This is a no-op for any heap that needs no bounds checks; e.g.,
294 if the limit is static and the guard region is large enough that
295 the index cannot reach past it.
296
297 This option is enabled by default because it is highly
298 recommended for secure sandboxing. The embedder should consider
299 the security implications carefully before disabling this option.
300 "#,
301 true,
302 );
303
304 settings.add_bool(
305 "enable_table_access_spectre_mitigation",
306 "Enable Spectre mitigation on table bounds checks.",
307 r#"
308 This option uses a conditional move to ensure that when a table
309 access index is bounds-checked and a conditional branch is used
310 for the out-of-bounds case, a misspeculation of that conditional
311 branch (falsely predicted in-bounds) will select an in-bounds
312 index to load on the speculative path.
313
314 This option is enabled by default because it is highly
315 recommended for secure sandboxing. The embedder should consider
316 the security implications carefully before disabling this option.
317 "#,
318 true,
319 );
320
321 settings.add_bool(
322 "enable_incremental_compilation_cache_checks",
323 "Enable additional checks for debugging the incremental compilation cache.",
324 r#"
325 Enables additional checks that are useful during development of the incremental
326 compilation cache. This should be mostly useful for Cranelift hackers, as well as for
327 helping to debug false incremental cache positives for embedders.
328
329 This option is disabled by default and requires enabling the "incremental-cache" Cargo
330 feature in cranelift-codegen.
331 "#,
332 false,
333 );
334
335 settings.add_num(
336 "bb_padding_log2_minus_one",
337 "The log2 of the size to insert dummy padding between basic blocks",
338 r#"
339 This is a debugging option for stressing various cases during code
340 generation without requiring large functions. This will insert
341 0-byte padding between basic blocks of the specified size.
342
343 The amount of padding inserted two raised to the power of this value
344 minus one. If this value is 0 then no padding is inserted.
345
346 The default for this option is 0 to insert no padding as it's only
347 intended for testing and development.
348 "#,
349 0,
350 );
351
352 settings.add_num(
353 "log2_min_function_alignment",
354 "The log2 of the minimum alignment of functions",
355 "The bigger of this value and the default alignment will be used as actual alignment.",
356 0,
357 );
358
359 settings.build()
362}