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Auto merge of #119911 - NCGThompson:is-statically-known, r=oli-obk

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Replacement of #114390: Add new intrinsic `is_var_statically_known` and optimize pow for powers of two

This adds a new intrinsic `is_val_statically_known` that lowers to [``@llvm.is.constant.*`](https://llvm.org/docs/LangRef.html#llvm-is-constant-intrinsic).` It also applies the intrinsic in the int_pow methods to recognize and optimize the idiom `2isize.pow(x)`. See #114390 for more discussion.

While I have extended the scope of the power of two optimization from #114390, I haven't added any new uses for the intrinsic. That can be done in later pull requests.

Note: When testing or using the library, be sure to use `--stage 1` or higher. Otherwise, the intrinsic will be a noop and the doctests will be skipped. If you are trying out edits, you may be interested in [`--keep-stage 0`](https://rustc-dev-guide.rust-lang.org/building/suggested.html#faster-builds-with---keep-stage).

Fixes #47234
Resolves #114390
`@Centri3`
This commit is contained in:
bors 2024-01-25 05:16:53 +00:00
commit d645e1638d
2 changed files with 10 additions and 3 deletions
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7
src/context.rs
View File

@ -196,15 +196,16 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
let mut functions = FxHashMap::default();
let builtins = [
"__builtin_unreachable", "abort", "__builtin_expect", "__builtin_add_overflow", "__builtin_mul_overflow",
"__builtin_saddll_overflow", /*"__builtin_sadd_overflow",*/ "__builtin_smulll_overflow", /*"__builtin_smul_overflow",*/
"__builtin_unreachable", "abort", "__builtin_expect", /*"__builtin_expect_with_probability",*/
"__builtin_constant_p", "__builtin_add_overflow", "__builtin_mul_overflow", "__builtin_saddll_overflow",
/*"__builtin_sadd_overflow",*/ "__builtin_smulll_overflow", /*"__builtin_smul_overflow",*/
"__builtin_ssubll_overflow", /*"__builtin_ssub_overflow",*/ "__builtin_sub_overflow", "__builtin_uaddll_overflow",
"__builtin_uadd_overflow", "__builtin_umulll_overflow", "__builtin_umul_overflow", "__builtin_usubll_overflow",
"__builtin_usub_overflow", "sqrtf", "sqrt", "__builtin_powif", "__builtin_powi", "sinf", "sin", "cosf", "cos",
"powf", "pow", "expf", "exp", "exp2f", "exp2", "logf", "log", "log10f", "log10", "log2f", "log2", "fmaf",
"fma", "fabsf", "fabs", "fminf", "fmin", "fmaxf", "fmax", "copysignf", "copysign", "floorf", "floor", "ceilf",
"ceil", "truncf", "trunc", "rintf", "rint", "nearbyintf", "nearbyint", "roundf", "round",
"__builtin_expect_with_probability",
];
for builtin in builtins.iter() {

6
src/intrinsic/mod.rs
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@ -123,6 +123,12 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
sym::unlikely => {
self.expect(args[0].immediate(), false)
}
sym::is_val_statically_known => {
let a = args[0].immediate();
let builtin = self.context.get_builtin_function("__builtin_constant_p");
let res = self.context.new_call(None, builtin, &[a]);
self.icmp(IntPredicate::IntEQ, res, self.const_i32(0))
}
kw::Try => {
try_intrinsic(
self,