summaryrefslogtreecommitdiffstats
path: root/vendor/compiler_builtins/build.rs
blob: 3f5dbd3ab2748e13c6a0d4ed9cf20e48c7523524 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
use std::env;

fn main() {
    println!("cargo:rerun-if-changed=build.rs");

    let target = env::var("TARGET").unwrap();
    let cwd = env::current_dir().unwrap();

    println!("cargo:compiler-rt={}", cwd.join("compiler-rt").display());

    // Activate libm's unstable features to make full use of Nightly.
    println!("cargo:rustc-cfg=feature=\"unstable\"");

    // Emscripten's runtime includes all the builtins
    if target.contains("emscripten") {
        return;
    }

    // OpenBSD provides compiler_rt by default, use it instead of rebuilding it from source
    if target.contains("openbsd") {
        println!("cargo:rustc-link-search=native=/usr/lib");
        println!("cargo:rustc-link-lib=compiler_rt");
        return;
    }

    // Forcibly enable memory intrinsics on wasm & SGX as we don't have a libc to
    // provide them.
    if (target.contains("wasm") && !target.contains("wasi"))
        || (target.contains("sgx") && target.contains("fortanix"))
        || target.contains("-none")
        || target.contains("nvptx")
        || target.contains("uefi")
    {
        println!("cargo:rustc-cfg=feature=\"mem\"");
    }

    // These targets have hardware unaligned access support.
    if target.contains("x86_64")
        || target.contains("i686")
        || target.contains("aarch64")
        || target.contains("bpf")
    {
        println!("cargo:rustc-cfg=feature=\"mem-unaligned\"");
    }

    // NOTE we are going to assume that llvm-target, what determines our codegen option, matches the
    // target triple. This is usually correct for our built-in targets but can break in presence of
    // custom targets, which can have arbitrary names.
    let llvm_target = target.split('-').collect::<Vec<_>>();

    // Build missing intrinsics from compiler-rt C source code. If we're
    // mangling names though we assume that we're also in test mode so we don't
    // build anything and we rely on the upstream implementation of compiler-rt
    // functions
    if !cfg!(feature = "mangled-names") && cfg!(feature = "c") {
        // Don't use a C compiler for these targets:
        //
        // * wasm - clang for wasm is somewhat hard to come by and it's
        //   unlikely that the C is really that much better than our own Rust.
        // * nvptx - everything is bitcode, not compatible with mixed C/Rust
        // * riscv - the rust-lang/rust distribution container doesn't have a C
        //   compiler.
        if !target.contains("wasm")
            && !target.contains("nvptx")
            && (!target.starts_with("riscv") || target.contains("xous"))
        {
            #[cfg(feature = "c")]
            c::compile(&llvm_target, &target);
        }
    }

    // To compile intrinsics.rs for thumb targets, where there is no libc
    if llvm_target[0].starts_with("thumb") {
        println!("cargo:rustc-cfg=thumb")
    }

    // compiler-rt `cfg`s away some intrinsics for thumbv6m and thumbv8m.base because
    // these targets do not have full Thumb-2 support but only original Thumb-1.
    // We have to cfg our code accordingly.
    if llvm_target[0] == "thumbv6m" || llvm_target[0] == "thumbv8m.base" {
        println!("cargo:rustc-cfg=thumb_1")
    }

    // Only emit the ARM Linux atomic emulation on pre-ARMv6 architectures. This
    // includes the old androideabi. It is deprecated but it is available as a
    // rustc target (arm-linux-androideabi).
    if llvm_target[0] == "armv4t"
        || llvm_target[0] == "armv5te"
        || target == "arm-linux-androideabi"
    {
        println!("cargo:rustc-cfg=kernel_user_helpers")
    }
}

#[cfg(feature = "c")]
mod c {
    extern crate cc;

    use std::collections::{BTreeMap, HashSet};
    use std::env;
    use std::fs::{self, File};
    use std::io::Write;
    use std::path::{Path, PathBuf};

    struct Sources {
        // SYMBOL -> PATH TO SOURCE
        map: BTreeMap<&'static str, &'static str>,
    }

    impl Sources {
        fn new() -> Sources {
            Sources {
                map: BTreeMap::new(),
            }
        }

        fn extend(&mut self, sources: &[(&'static str, &'static str)]) {
            // NOTE Some intrinsics have both a generic implementation (e.g.
            // `floatdidf.c`) and an arch optimized implementation
            // (`x86_64/floatdidf.c`). In those cases, we keep the arch optimized
            // implementation and discard the generic implementation. If we don't
            // and keep both implementations, the linker will yell at us about
            // duplicate symbols!
            for (symbol, src) in sources {
                if src.contains("/") {
                    // Arch-optimized implementation (preferred)
                    self.map.insert(symbol, src);
                } else {
                    // Generic implementation
                    if !self.map.contains_key(symbol) {
                        self.map.insert(symbol, src);
                    }
                }
            }
        }

        fn remove(&mut self, symbols: &[&str]) {
            for symbol in symbols {
                self.map.remove(*symbol).unwrap();
            }
        }
    }

    /// Compile intrinsics from the compiler-rt C source code
    pub fn compile(llvm_target: &[&str], target: &String) {
        let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
        let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
        let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap();
        let target_vendor = env::var("CARGO_CFG_TARGET_VENDOR").unwrap();
        let mut consider_float_intrinsics = true;
        let cfg = &mut cc::Build::new();

        // AArch64 GCCs exit with an error condition when they encounter any kind of floating point
        // code if the `nofp` and/or `nosimd` compiler flags have been set.
        //
        // Therefore, evaluate if those flags are present and set a boolean that causes any
        // compiler-rt intrinsics that contain floating point source to be excluded for this target.
        if target_arch == "aarch64" {
            let cflags_key = String::from("CFLAGS_") + &(target.to_owned().replace("-", "_"));
            if let Ok(cflags_value) = env::var(cflags_key) {
                if cflags_value.contains("+nofp") || cflags_value.contains("+nosimd") {
                    consider_float_intrinsics = false;
                }
            }
        }

        cfg.warnings(false);

        if target_env == "msvc" {
            // Don't pull in extra libraries on MSVC
            cfg.flag("/Zl");

            // Emulate C99 and C++11's __func__ for MSVC prior to 2013 CTP
            cfg.define("__func__", Some("__FUNCTION__"));
        } else {
            // Turn off various features of gcc and such, mostly copying
            // compiler-rt's build system already
            cfg.flag("-fno-builtin");
            cfg.flag("-fvisibility=hidden");
            cfg.flag("-ffreestanding");
            // Avoid the following warning appearing once **per file**:
            // clang: warning: optimization flag '-fomit-frame-pointer' is not supported for target 'armv7' [-Wignored-optimization-argument]
            //
            // Note that compiler-rt's build system also checks
            //
            // `check_cxx_compiler_flag(-fomit-frame-pointer COMPILER_RT_HAS_FOMIT_FRAME_POINTER_FLAG)`
            //
            // in https://github.com/rust-lang/compiler-rt/blob/c8fbcb3/cmake/config-ix.cmake#L19.
            cfg.flag_if_supported("-fomit-frame-pointer");
            cfg.define("VISIBILITY_HIDDEN", None);
        }

        // int_util.c tries to include stdlib.h if `_WIN32` is defined,
        // which it is when compiling UEFI targets with clang. This is
        // at odds with compiling with `-ffreestanding`, as the header
        // may be incompatible or not present. Create a minimal stub
        // header to use instead.
        if target_os == "uefi" {
            let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
            let include_dir = out_dir.join("include");
            if !include_dir.exists() {
                fs::create_dir(&include_dir).unwrap();
            }
            fs::write(include_dir.join("stdlib.h"), "#include <stddef.h>").unwrap();
            cfg.flag(&format!("-I{}", include_dir.to_str().unwrap()));
        }

        let mut sources = Sources::new();
        sources.extend(&[
            ("__absvdi2", "absvdi2.c"),
            ("__absvsi2", "absvsi2.c"),
            ("__addvdi3", "addvdi3.c"),
            ("__addvsi3", "addvsi3.c"),
            ("__clzdi2", "clzdi2.c"),
            ("__clzsi2", "clzsi2.c"),
            ("__cmpdi2", "cmpdi2.c"),
            ("__ctzdi2", "ctzdi2.c"),
            ("__ctzsi2", "ctzsi2.c"),
            ("__int_util", "int_util.c"),
            ("__mulvdi3", "mulvdi3.c"),
            ("__mulvsi3", "mulvsi3.c"),
            ("__negdi2", "negdi2.c"),
            ("__negvdi2", "negvdi2.c"),
            ("__negvsi2", "negvsi2.c"),
            ("__paritydi2", "paritydi2.c"),
            ("__paritysi2", "paritysi2.c"),
            ("__popcountdi2", "popcountdi2.c"),
            ("__popcountsi2", "popcountsi2.c"),
            ("__subvdi3", "subvdi3.c"),
            ("__subvsi3", "subvsi3.c"),
            ("__ucmpdi2", "ucmpdi2.c"),
        ]);

        if consider_float_intrinsics {
            sources.extend(&[
                ("__divdc3", "divdc3.c"),
                ("__divsc3", "divsc3.c"),
                ("__divxc3", "divxc3.c"),
                ("__extendhfsf2", "extendhfsf2.c"),
                ("__muldc3", "muldc3.c"),
                ("__mulsc3", "mulsc3.c"),
                ("__mulxc3", "mulxc3.c"),
                ("__negdf2", "negdf2.c"),
                ("__negsf2", "negsf2.c"),
                ("__powixf2", "powixf2.c"),
                ("__truncdfhf2", "truncdfhf2.c"),
                ("__truncsfhf2", "truncsfhf2.c"),
            ]);
        }

        // When compiling in rustbuild (the rust-lang/rust repo) this library
        // also needs to satisfy intrinsics that jemalloc or C in general may
        // need, so include a few more that aren't typically needed by
        // LLVM/Rust.
        if cfg!(feature = "rustbuild") {
            sources.extend(&[("__ffsdi2", "ffsdi2.c")]);
        }

        // On iOS and 32-bit OSX these are all just empty intrinsics, no need to
        // include them.
        if target_os != "ios"
            && target_os != "watchos"
            && (target_vendor != "apple" || target_arch != "x86")
        {
            sources.extend(&[
                ("__absvti2", "absvti2.c"),
                ("__addvti3", "addvti3.c"),
                ("__clzti2", "clzti2.c"),
                ("__cmpti2", "cmpti2.c"),
                ("__ctzti2", "ctzti2.c"),
                ("__ffsti2", "ffsti2.c"),
                ("__mulvti3", "mulvti3.c"),
                ("__negti2", "negti2.c"),
                ("__parityti2", "parityti2.c"),
                ("__popcountti2", "popcountti2.c"),
                ("__subvti3", "subvti3.c"),
                ("__ucmpti2", "ucmpti2.c"),
            ]);

            if consider_float_intrinsics {
                sources.extend(&[("__negvti2", "negvti2.c")]);
            }
        }

        if target_vendor == "apple" {
            sources.extend(&[
                ("atomic_flag_clear", "atomic_flag_clear.c"),
                ("atomic_flag_clear_explicit", "atomic_flag_clear_explicit.c"),
                ("atomic_flag_test_and_set", "atomic_flag_test_and_set.c"),
                (
                    "atomic_flag_test_and_set_explicit",
                    "atomic_flag_test_and_set_explicit.c",
                ),
                ("atomic_signal_fence", "atomic_signal_fence.c"),
                ("atomic_thread_fence", "atomic_thread_fence.c"),
            ]);
        }

        if target_env == "msvc" {
            if target_arch == "x86_64" {
                sources.extend(&[("__floatdixf", "x86_64/floatdixf.c")]);
            }
        } else {
            // None of these seem to be used on x86_64 windows, and they've all
            // got the wrong ABI anyway, so we want to avoid them.
            if target_os != "windows" {
                if target_arch == "x86_64" {
                    sources.extend(&[
                        ("__floatdixf", "x86_64/floatdixf.c"),
                        ("__floatundixf", "x86_64/floatundixf.S"),
                    ]);
                }
            }

            if target_arch == "x86" {
                sources.extend(&[
                    ("__ashldi3", "i386/ashldi3.S"),
                    ("__ashrdi3", "i386/ashrdi3.S"),
                    ("__divdi3", "i386/divdi3.S"),
                    ("__floatdixf", "i386/floatdixf.S"),
                    ("__floatundixf", "i386/floatundixf.S"),
                    ("__lshrdi3", "i386/lshrdi3.S"),
                    ("__moddi3", "i386/moddi3.S"),
                    ("__muldi3", "i386/muldi3.S"),
                    ("__udivdi3", "i386/udivdi3.S"),
                    ("__umoddi3", "i386/umoddi3.S"),
                ]);
            }
        }

        if target_arch == "arm"
            && target_os != "ios"
            && target_os != "watchos"
            && target_env != "msvc"
        {
            sources.extend(&[
                ("__aeabi_div0", "arm/aeabi_div0.c"),
                ("__aeabi_drsub", "arm/aeabi_drsub.c"),
                ("__aeabi_frsub", "arm/aeabi_frsub.c"),
                ("__bswapdi2", "arm/bswapdi2.S"),
                ("__bswapsi2", "arm/bswapsi2.S"),
                ("__clzdi2", "arm/clzdi2.S"),
                ("__clzsi2", "arm/clzsi2.S"),
                ("__divmodsi4", "arm/divmodsi4.S"),
                ("__divsi3", "arm/divsi3.S"),
                ("__modsi3", "arm/modsi3.S"),
                ("__switch16", "arm/switch16.S"),
                ("__switch32", "arm/switch32.S"),
                ("__switch8", "arm/switch8.S"),
                ("__switchu8", "arm/switchu8.S"),
                ("__sync_synchronize", "arm/sync_synchronize.S"),
                ("__udivmodsi4", "arm/udivmodsi4.S"),
                ("__udivsi3", "arm/udivsi3.S"),
                ("__umodsi3", "arm/umodsi3.S"),
            ]);

            if target_os == "freebsd" {
                sources.extend(&[("__clear_cache", "clear_cache.c")]);
            }

            // First of all aeabi_cdcmp and aeabi_cfcmp are never called by LLVM.
            // Second are little-endian only, so build fail on big-endian targets.
            // Temporally workaround: exclude these files for big-endian targets.
            if !llvm_target[0].starts_with("thumbeb") && !llvm_target[0].starts_with("armeb") {
                sources.extend(&[
                    ("__aeabi_cdcmp", "arm/aeabi_cdcmp.S"),
                    ("__aeabi_cdcmpeq_check_nan", "arm/aeabi_cdcmpeq_check_nan.c"),
                    ("__aeabi_cfcmp", "arm/aeabi_cfcmp.S"),
                    ("__aeabi_cfcmpeq_check_nan", "arm/aeabi_cfcmpeq_check_nan.c"),
                ]);
            }
        }

        if llvm_target[0] == "armv7" {
            sources.extend(&[
                ("__sync_fetch_and_add_4", "arm/sync_fetch_and_add_4.S"),
                ("__sync_fetch_and_add_8", "arm/sync_fetch_and_add_8.S"),
                ("__sync_fetch_and_and_4", "arm/sync_fetch_and_and_4.S"),
                ("__sync_fetch_and_and_8", "arm/sync_fetch_and_and_8.S"),
                ("__sync_fetch_and_max_4", "arm/sync_fetch_and_max_4.S"),
                ("__sync_fetch_and_max_8", "arm/sync_fetch_and_max_8.S"),
                ("__sync_fetch_and_min_4", "arm/sync_fetch_and_min_4.S"),
                ("__sync_fetch_and_min_8", "arm/sync_fetch_and_min_8.S"),
                ("__sync_fetch_and_nand_4", "arm/sync_fetch_and_nand_4.S"),
                ("__sync_fetch_and_nand_8", "arm/sync_fetch_and_nand_8.S"),
                ("__sync_fetch_and_or_4", "arm/sync_fetch_and_or_4.S"),
                ("__sync_fetch_and_or_8", "arm/sync_fetch_and_or_8.S"),
                ("__sync_fetch_and_sub_4", "arm/sync_fetch_and_sub_4.S"),
                ("__sync_fetch_and_sub_8", "arm/sync_fetch_and_sub_8.S"),
                ("__sync_fetch_and_umax_4", "arm/sync_fetch_and_umax_4.S"),
                ("__sync_fetch_and_umax_8", "arm/sync_fetch_and_umax_8.S"),
                ("__sync_fetch_and_umin_4", "arm/sync_fetch_and_umin_4.S"),
                ("__sync_fetch_and_umin_8", "arm/sync_fetch_and_umin_8.S"),
                ("__sync_fetch_and_xor_4", "arm/sync_fetch_and_xor_4.S"),
                ("__sync_fetch_and_xor_8", "arm/sync_fetch_and_xor_8.S"),
            ]);
        }

        if llvm_target.last().unwrap().ends_with("eabihf") {
            if !llvm_target[0].starts_with("thumbv7em")
                && !llvm_target[0].starts_with("thumbv8m.main")
            {
                // The FPU option chosen for these architectures in cc-rs, ie:
                //     -mfpu=fpv4-sp-d16 for thumbv7em
                //     -mfpu=fpv5-sp-d16 for thumbv8m.main
                // do not support double precision floating points conversions so the files
                // that include such instructions are not included for these targets.
                sources.extend(&[
                    ("__fixdfsivfp", "arm/fixdfsivfp.S"),
                    ("__fixunsdfsivfp", "arm/fixunsdfsivfp.S"),
                    ("__floatsidfvfp", "arm/floatsidfvfp.S"),
                    ("__floatunssidfvfp", "arm/floatunssidfvfp.S"),
                ]);
            }

            sources.extend(&[
                ("__fixsfsivfp", "arm/fixsfsivfp.S"),
                ("__fixunssfsivfp", "arm/fixunssfsivfp.S"),
                ("__floatsisfvfp", "arm/floatsisfvfp.S"),
                ("__floatunssisfvfp", "arm/floatunssisfvfp.S"),
                ("__floatunssisfvfp", "arm/floatunssisfvfp.S"),
                ("__restore_vfp_d8_d15_regs", "arm/restore_vfp_d8_d15_regs.S"),
                ("__save_vfp_d8_d15_regs", "arm/save_vfp_d8_d15_regs.S"),
                ("__negdf2vfp", "arm/negdf2vfp.S"),
                ("__negsf2vfp", "arm/negsf2vfp.S"),
            ]);
        }

        if target_arch == "aarch64" && consider_float_intrinsics {
            sources.extend(&[
                ("__comparetf2", "comparetf2.c"),
                ("__extenddftf2", "extenddftf2.c"),
                ("__extendsftf2", "extendsftf2.c"),
                ("__fixtfdi", "fixtfdi.c"),
                ("__fixtfsi", "fixtfsi.c"),
                ("__fixtfti", "fixtfti.c"),
                ("__fixunstfdi", "fixunstfdi.c"),
                ("__fixunstfsi", "fixunstfsi.c"),
                ("__fixunstfti", "fixunstfti.c"),
                ("__floatditf", "floatditf.c"),
                ("__floatsitf", "floatsitf.c"),
                ("__floatunditf", "floatunditf.c"),
                ("__floatunsitf", "floatunsitf.c"),
                ("__trunctfdf2", "trunctfdf2.c"),
                ("__trunctfsf2", "trunctfsf2.c"),
                ("__addtf3", "addtf3.c"),
                ("__multf3", "multf3.c"),
                ("__subtf3", "subtf3.c"),
                ("__divtf3", "divtf3.c"),
                ("__powitf2", "powitf2.c"),
                ("__fe_getround", "fp_mode.c"),
                ("__fe_raise_inexact", "fp_mode.c"),
            ]);

            if target_os != "windows" {
                sources.extend(&[("__multc3", "multc3.c")]);
            }
        }

        if target_arch == "mips" {
            sources.extend(&[("__bswapsi2", "bswapsi2.c")]);
        }

        if target_arch == "mips64" {
            sources.extend(&[
                ("__extenddftf2", "extenddftf2.c"),
                ("__netf2", "comparetf2.c"),
                ("__addtf3", "addtf3.c"),
                ("__multf3", "multf3.c"),
                ("__subtf3", "subtf3.c"),
                ("__fixtfsi", "fixtfsi.c"),
                ("__floatsitf", "floatsitf.c"),
                ("__fixunstfsi", "fixunstfsi.c"),
                ("__floatunsitf", "floatunsitf.c"),
                ("__fe_getround", "fp_mode.c"),
                ("__divtf3", "divtf3.c"),
                ("__trunctfdf2", "trunctfdf2.c"),
                ("__trunctfsf2", "trunctfsf2.c"),
            ]);
        }

        // Remove the assembly implementations that won't compile for the target
        if llvm_target[0] == "thumbv6m" || llvm_target[0] == "thumbv8m.base" || target_os == "uefi"
        {
            let mut to_remove = Vec::new();
            for (k, v) in sources.map.iter() {
                if v.ends_with(".S") {
                    to_remove.push(*k);
                }
            }
            sources.remove(&to_remove);

            // But use some generic implementations where possible
            sources.extend(&[("__clzdi2", "clzdi2.c"), ("__clzsi2", "clzsi2.c")])
        }

        if llvm_target[0] == "thumbv7m" || llvm_target[0] == "thumbv7em" {
            sources.remove(&["__aeabi_cdcmp", "__aeabi_cfcmp"]);
        }

        // Android uses emulated TLS so we need a runtime support function.
        if target_os == "android" {
            sources.extend(&[("__emutls_get_address", "emutls.c")]);

            // Work around a bug in the NDK headers (fixed in
            // https://r.android.com/2038949 which will be released in a future
            // NDK version) by providing a definition of LONG_BIT.
            cfg.define("LONG_BIT", "(8 * sizeof(long))");
        }

        // When compiling the C code we require the user to tell us where the
        // source code is, and this is largely done so when we're compiling as
        // part of rust-lang/rust we can use the same llvm-project repository as
        // rust-lang/rust.
        let root = match env::var_os("RUST_COMPILER_RT_ROOT") {
            Some(s) => PathBuf::from(s),
            None => panic!("RUST_COMPILER_RT_ROOT is not set"),
        };
        if !root.exists() {
            panic!("RUST_COMPILER_RT_ROOT={} does not exist", root.display());
        }

        // Support deterministic builds by remapping the __FILE__ prefix if the
        // compiler supports it.  This fixes the nondeterminism caused by the
        // use of that macro in lib/builtins/int_util.h in compiler-rt.
        cfg.flag_if_supported(&format!("-ffile-prefix-map={}=.", root.display()));

        // Include out-of-line atomics for aarch64, which are all generated by supplying different
        // sets of flags to the same source file.
        // Note: Out-of-line aarch64 atomics are not supported by the msvc toolchain (#430).
        let src_dir = root.join("lib/builtins");
        if target_arch == "aarch64" && target_env != "msvc" {
            // See below for why we're building these as separate libraries.
            build_aarch64_out_of_line_atomics_libraries(&src_dir, cfg);

            // Some run-time CPU feature detection is necessary, as well.
            sources.extend(&[("__aarch64_have_lse_atomics", "cpu_model.c")]);
        }

        let mut added_sources = HashSet::new();
        for (sym, src) in sources.map.iter() {
            let src = src_dir.join(src);
            if added_sources.insert(src.clone()) {
                cfg.file(&src);
                println!("cargo:rerun-if-changed={}", src.display());
            }
            println!("cargo:rustc-cfg={}=\"optimized-c\"", sym);
        }

        cfg.compile("libcompiler-rt.a");
    }

    fn build_aarch64_out_of_line_atomics_libraries(builtins_dir: &Path, cfg: &mut cc::Build) {
        let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
        let outlined_atomics_file = builtins_dir.join("aarch64/lse.S");
        println!("cargo:rerun-if-changed={}", outlined_atomics_file.display());

        cfg.include(&builtins_dir);

        for instruction_type in &["cas", "swp", "ldadd", "ldclr", "ldeor", "ldset"] {
            for size in &[1, 2, 4, 8, 16] {
                if *size == 16 && *instruction_type != "cas" {
                    continue;
                }

                for (model_number, model_name) in
                    &[(1, "relax"), (2, "acq"), (3, "rel"), (4, "acq_rel")]
                {
                    // The original compiler-rt build system compiles the same
                    // source file multiple times with different compiler
                    // options. Here we do something slightly different: we
                    // create multiple .S files with the proper #defines and
                    // then include the original file.
                    //
                    // This is needed because the cc crate doesn't allow us to
                    // override the name of object files and libtool requires
                    // all objects in an archive to have unique names.
                    let path =
                        out_dir.join(format!("lse_{}{}_{}.S", instruction_type, size, model_name));
                    let mut file = File::create(&path).unwrap();
                    writeln!(file, "#define L_{}", instruction_type).unwrap();
                    writeln!(file, "#define SIZE {}", size).unwrap();
                    writeln!(file, "#define MODEL {}", model_number).unwrap();
                    writeln!(
                        file,
                        "#include \"{}\"",
                        outlined_atomics_file.canonicalize().unwrap().display()
                    )
                    .unwrap();
                    drop(file);
                    cfg.file(path);

                    let sym = format!("__aarch64_{}{}_{}", instruction_type, size, model_name);
                    println!("cargo:rustc-cfg={}=\"optimized-c\"", sym);
                }
            }
        }
    }
}