Add benchmarks using iai-callgrind

Running walltime benchmarks in CI is notoriously unstable, Introduce
benchmarks that instead use instruction count and other more
reproducible metrics, using `iai-callgrind` [1], which we are able to
run in CI with a high degree of reproducibility.

Inputs to this benchmark are a logspace sweep, which gives an
approximation for real-world use, but may fail to indicate outlier
cases.

[1]: https://github.com/iai-callgrind/iai-callgrind

library/compiler-builtins/libm/Cargo.toml

@@ -73,3 +73,7 @@ debug-assertions = true
 inherits = "release"
 lto = "fat"
 overflow-checks = true
+
+[profile.bench]
+# Required for iai-callgrind
+debug = true

library/compiler-builtins/libm/crates/libm-test/Cargo.toml

@@ -20,6 +20,9 @@ build-musl = ["dep:musl-math-sys"]
 # Enable report generation without bringing in more dependencies by default
 benchmarking-reports = ["criterion/plotters", "criterion/html_reports"]
 
+# Enable icount benchmarks (requires iai-callgrind and valgrind)
+icount = ["dep:iai-callgrind"]
+
 # Run with a reduced set of benchmarks, such as for CI
 short-benchmarks = []
 
@@ -27,6 +30,7 @@ short-benchmarks = []
 anyhow = "1.0.90"
 az = { version = "1.2.1", optional = true }
 gmp-mpfr-sys = { version = "1.6.4", optional = true, default-features = false, features = ["mpfr"] }
+iai-callgrind = { version = "0.14.0", optional = true }
 indicatif = { version = "0.17.9", default-features = false }
 libm = { path = "../..", features = ["unstable-public-internals"] }
 libm-macros = { path = "../libm-macros" }
@@ -48,6 +52,11 @@ rand = { version = "0.8.5", optional = true }
 criterion = { version = "0.5.1", default-features = false, features = ["cargo_bench_support"] }
 libtest-mimic = "0.8.1"
 
+[[bench]]
+name = "icount"
+harness = false
+required-features = ["icount"]
+
 [[bench]]
 name = "random"
 harness = false

library/compiler-builtins/libm/crates/libm-test/benches/icount.rs

@@ -0,0 +1,175 @@
+//! Benchmarks that use `iai-cachegrind` to be reasonably CI-stable.
+
+use std::hint::black_box;
+
+use iai_callgrind::{library_benchmark, library_benchmark_group, main};
+use libm_test::gen::spaced;
+use libm_test::{CheckBasis, CheckCtx, GeneratorKind, MathOp, OpRustArgs, TupleCall, op};
+
+const BENCH_ITER_ITEMS: u64 = 500;
+
+macro_rules! icount_benches {
+    (
+        fn_name: $fn_name:ident,
+        attrs: [$($_attr:meta),*],
+    ) => {
+        paste::paste! {
+            // Construct benchmark inputs from the logspace generator.
+            fn [< setup_ $fn_name >]() -> Vec<OpRustArgs<op::$fn_name::Routine>> {
+                type Op = op::$fn_name::Routine;
+                let mut ctx = CheckCtx::new(
+                    Op::IDENTIFIER,
+                    CheckBasis::None,
+                    GeneratorKind::QuickSpaced
+                );
+                ctx.override_iterations(BENCH_ITER_ITEMS);
+                let ret = spaced::get_test_cases::<Op>(&ctx).0.collect::<Vec<_>>();
+                println!("operation {}, {} steps", Op::NAME, ret.len());
+                ret
+            }
+
+            // Run benchmarks with the above inputs.
+            #[library_benchmark]
+            #[bench::logspace([< setup_ $fn_name >]())]
+            fn [< icount_bench_ $fn_name >](cases: Vec<OpRustArgs<op::$fn_name::Routine>>) {
+                type Op = op::$fn_name::Routine;
+                let f = black_box(Op::ROUTINE);
+                for input in cases.iter().copied() {
+                    input.call(f);
+                }
+            }
+
+            library_benchmark_group!(
+                name = [< icount_bench_ $fn_name _group  >];
+                benchmarks = [< icount_bench_ $fn_name >]
+            );
+        }
+    };
+}
+
+libm_macros::for_each_function! {
+    callback: icount_benches,
+}
+
+main!(
+    library_benchmark_groups = icount_bench_acos_group,
+    icount_bench_acosf_group,
+    icount_bench_acosh_group,
+    icount_bench_acoshf_group,
+    icount_bench_asin_group,
+    icount_bench_asinf_group,
+    icount_bench_asinh_group,
+    icount_bench_asinhf_group,
+    icount_bench_atan2_group,
+    icount_bench_atan2f_group,
+    icount_bench_atan_group,
+    icount_bench_atanf_group,
+    icount_bench_atanh_group,
+    icount_bench_atanhf_group,
+    icount_bench_cbrt_group,
+    icount_bench_cbrtf_group,
+    icount_bench_ceil_group,
+    icount_bench_ceilf_group,
+    icount_bench_copysign_group,
+    icount_bench_copysignf128_group,
+    icount_bench_copysignf16_group,
+    icount_bench_copysignf_group,
+    icount_bench_cos_group,
+    icount_bench_cosf_group,
+    icount_bench_cosh_group,
+    icount_bench_coshf_group,
+    icount_bench_erf_group,
+    icount_bench_erfc_group,
+    icount_bench_erfcf_group,
+    icount_bench_erff_group,
+    icount_bench_exp10_group,
+    icount_bench_exp10f_group,
+    icount_bench_exp2_group,
+    icount_bench_exp2f_group,
+    icount_bench_exp_group,
+    icount_bench_expf_group,
+    icount_bench_expm1_group,
+    icount_bench_expm1f_group,
+    icount_bench_fabs_group,
+    icount_bench_fabsf128_group,
+    icount_bench_fabsf16_group,
+    icount_bench_fabsf_group,
+    icount_bench_fdim_group,
+    icount_bench_fdimf128_group,
+    icount_bench_fdimf16_group,
+    icount_bench_fdimf_group,
+    icount_bench_floor_group,
+    icount_bench_floorf_group,
+    icount_bench_fma_group,
+    icount_bench_fmaf_group,
+    icount_bench_fmax_group,
+    icount_bench_fmaxf_group,
+    icount_bench_fmin_group,
+    icount_bench_fminf_group,
+    icount_bench_fmod_group,
+    icount_bench_fmodf_group,
+    icount_bench_frexp_group,
+    icount_bench_frexpf_group,
+    icount_bench_hypot_group,
+    icount_bench_hypotf_group,
+    icount_bench_ilogb_group,
+    icount_bench_ilogbf_group,
+    icount_bench_j0_group,
+    icount_bench_j0f_group,
+    icount_bench_j1_group,
+    icount_bench_j1f_group,
+    icount_bench_jn_group,
+    icount_bench_jnf_group,
+    icount_bench_ldexp_group,
+    icount_bench_ldexpf_group,
+    icount_bench_lgamma_group,
+    icount_bench_lgamma_r_group,
+    icount_bench_lgammaf_group,
+    icount_bench_lgammaf_r_group,
+    icount_bench_log10_group,
+    icount_bench_log10f_group,
+    icount_bench_log1p_group,
+    icount_bench_log1pf_group,
+    icount_bench_log2_group,
+    icount_bench_log2f_group,
+    icount_bench_log_group,
+    icount_bench_logf_group,
+    icount_bench_modf_group,
+    icount_bench_modff_group,
+    icount_bench_nextafter_group,
+    icount_bench_nextafterf_group,
+    icount_bench_pow_group,
+    icount_bench_powf_group,
+    icount_bench_remainder_group,
+    icount_bench_remainderf_group,
+    icount_bench_remquo_group,
+    icount_bench_remquof_group,
+    icount_bench_rint_group,
+    icount_bench_rintf_group,
+    icount_bench_round_group,
+    icount_bench_roundf_group,
+    icount_bench_scalbn_group,
+    icount_bench_scalbnf_group,
+    icount_bench_sin_group,
+    icount_bench_sinf_group,
+    icount_bench_sinh_group,
+    icount_bench_sinhf_group,
+    icount_bench_sqrt_group,
+    icount_bench_sqrtf_group,
+    icount_bench_tan_group,
+    icount_bench_tanf_group,
+    icount_bench_tanh_group,
+    icount_bench_tanhf_group,
+    icount_bench_tgamma_group,
+    icount_bench_tgammaf_group,
+    icount_bench_trunc_group,
+    icount_bench_truncf128_group,
+    icount_bench_truncf16_group,
+    icount_bench_truncf_group,
+    icount_bench_y0_group,
+    icount_bench_y0f_group,
+    icount_bench_y1_group,
+    icount_bench_y1f_group,
+    icount_bench_yn_group,
+    icount_bench_ynf_group,
+);

library/compiler-builtins/libm/crates/libm-test/src/lib.rs

@@ -24,7 +24,8 @@ pub use f8_impl::f8;
 pub use libm::support::{Float, Int, IntTy, MinInt};
 pub use num::{FloatExt, linear_ints, logspace};
 pub use op::{
-    BaseName, FloatTy, Identifier, MathOp, OpCFn, OpCRet, OpFTy, OpRustFn, OpRustRet, Ty,
+    BaseName, FloatTy, Identifier, MathOp, OpCFn, OpCRet, OpFTy, OpRustArgs, OpRustFn, OpRustRet,
+    Ty,
 };
 pub use precision::{MaybeOverride, SpecialCase, default_ulp};
 use run_cfg::EXTENSIVE_MAX_ITERATIONS;

library/compiler-builtins/libm/crates/libm-test/src/op.rs

@@ -100,6 +100,8 @@ pub type OpCFn<Op> = <Op as MathOp>::CFn;
 pub type OpCRet<Op> = <Op as MathOp>::CRet;
 /// Access the associated `RustFn` type from an op (helper to avoid ambiguous associated types).
 pub type OpRustFn<Op> = <Op as MathOp>::RustFn;
+/// Access the associated `RustArgs` type from an op (helper to avoid ambiguous associated types).
+pub type OpRustArgs<Op> = <Op as MathOp>::RustArgs;
 /// Access the associated `RustRet` type from an op (helper to avoid ambiguous associated types).
 pub type OpRustRet<Op> = <Op as MathOp>::RustRet;