Better float casting tests in coretests

[eggyal]

A direct port of the float casting tests from MIRI.

Closes #152592

r? tgross35

[rustbot]

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[rust-log-analyzer]

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

REPOSITORY                                   TAG       IMAGE ID       CREATED       SIZE
ghcr.io/dependabot/dependabot-updater-core   latest    afc745c7535d   2 weeks ago   783MB
=> Removing docker images...
Deleted Images:
untagged: ghcr.io/dependabot/dependabot-updater-core:latest
untagged: ghcr.io/dependabot/dependabot-updater-core@sha256:faae3d3a1dedd24cde388bb506bbacc0f7ed1eae99ebac129af66acd8540c84a
deleted: sha256:afc745c7535da1bb12f92c273b9a7e9c52c3f12c5873714b2542da259c6d9769
deleted: sha256:64e147d5e54d9be8b8aa322e511cda02296eda4b8b8d063c6a314833aca50e29
deleted: sha256:5cba409bb463f4e7fa1a19f695450170422582c1bc7c0e934d893b4e5f558bc6
deleted: sha256:cddc6ebd344b0111eaab170ead1dfda24acdfe865ed8a12599a34d338fa8e28b
deleted: sha256:2412c3f334d79134573cd45e657fb6cc0abd75bef3881458b0d498d936545c8d
---
[RUSTC-TIMING] corebenches test:true 9.150
[RUSTC-TIMING] allocbenches test:true 7.771
[RUSTC-TIMING] alloctests test:true 18.276
[RUSTC-TIMING] alloctests test:true 18.292
error: VerifierErrors([VerifierError { location: inst10, context: Some("v10 = select.i32 v8, v6, v5  ; v6 = -128"), message: "arg 2 (v5) has type i8, expected i32" }])

error: cranelift verify error:
       function u0:535(f128, i8, i64, i64) system_v {
           ss0 = explicit_slot 16, align = 8
           ss1 = explicit_slot 16, align = 8
           ss2 = explicit_slot 8, align = 8
           ss3 = explicit_slot 16, align = 8
           ss4 = explicit_slot 16, align = 8
           gv0 = symbol colocated userextname3
           gv1 = symbol colocated userextname5
           sig0 = (f128) -> i8 system_v
           sig1 = (f128, f128) -> i32 system_v
           sig2 = (i64 sret, i64) system_v
           sig3 = (i64, i64) -> i64, i64 system_v
           sig4 = (i8, i8, i64, i64, i64) system_v
           fn0 = u0:1272 sig0
           fn1 = u0:1054 sig1
           fn2 = u0:917 sig2
           fn3 = u0:1267 sig3
           fn4 = colocated u0:25 sig4
       
                                       block0(v0: f128, v1: i8, v2: i64, v3: i64):
                                           v4 -> v0
                                           v33 -> v1
                                           nop 
                                           stack_store v2, ss0
                                           stack_store v3, ss0+8
                                           jump block1
       
                                       block1:
                                           nop 
       @0000                               v5 = call fn0(v4)
       @0000                               v6 = iconst.i32 -128
       @0000                               v7 = iconst.i32 127
       @0000                               v8 = icmp_imm slt v5, -128
       @0000                               v9 = icmp_imm sgt v5, 127
       @0000                               v10 = select v8, v6, v5  ; v6 = -128
       ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       ; error: inst10 (v10 = select.i32 v8, v6, v5  ; v6 = -128): arg 2 (v5) has type i8, expected i32
       
       @0000                               v11 = select v9, v7, v10  ; v7 = 127
       @0000                               v12 = ireduce.i8 v11
       @0000                               v13 = call fn1(v4, v4)
       @0000                               v14 = iconst.i32 0
       @0000                               v15 = icmp eq v13, v14  ; v14 = 0
       @0000                               v16 = iconst.i8 0
       @0000                               v17 = select v15, v12, v16  ; v16 = 0
                                           v32 -> v17
       @0001                               v18 = stack_addr.i64 ss0
       @0001                               stack_store v18, ss2
       @0001                               v19 = stack_load.i64 ss2
       @0001                               v20 = stack_addr.i64 ss4
       @0001                               call fn2(v20, v19)
       @0001                               jump block2
       
                                       block2:
       @0001                               nop 
       @0001                               v21 = iconst.i64 0
       @0001                               v22 = imul_imm v21, 16  ; v21 = 0
       @0001                               v23 = stack_addr.i64 ss3
       @0001                               v24 = iadd v23, v22
       @0001                               v25 = stack_addr.i64 ss4
       @0001                               v26 = load.i64 notrap aligned v25
       @0001                               v27 = load.i64 notrap aligned v25+8
       @0001                               store notrap aligned v26, v24
       @0001                               store notrap aligned v27, v24+8
       @0001                               v28 = symbol_value.i64 gv0
       @0001                               v29 = stack_addr.i64 ss3
       @0001                               v30, v31 = call fn3(v28, v29)
       @0001                               stack_store v30, ss1
       @0001                               stack_store v31, ss1+8
       @0001                               jump block3
       
                                       block3:
       @0001                               nop 
       @0002                               v34 = symbol_value.i64 gv1
       @0002                               v35 = stack_load.i64 ss1
       @0002                               v36 = stack_load.i64 ss1+8
       @0002                               call fn4(v32, v33, v35, v36, v34)
       @0002                               jump block4
       
                                       block4:
       @0002                               nop 
       @0003                               return
       }
       
       ; 1 verifier error detected (see above). Compilation aborted.
       

fn floats::casts::casts::assert_ftoi_unrep(_1: f128, _2: i8, _3: &str) -> () {
    debug f => _1;
    debug i => _2;
    debug msg => _3;
    let mut _0: ();
    let _4: ();
    let mut _5: i8;
    let mut _6: std::fmt::Arguments<'_>;
    let _7: (&&str,);
    let mut _8: &&str;
    let mut _10: core::fmt::rt::Argument<'_>;
    let mut _11: &[u8; 15];
    let _12: &[core::fmt::rt::Argument<'_>; 1];
    let mut _13: &&str;
    scope 1 {
        debug args => _7;
        let _9: [core::fmt::rt::Argument<'_>; 1];
        scope 2 {
            debug args => _9;
        }
    }

    bb0: {
        _5 = copy _1 as i8 (FloatToInt);
        _8 = &_3;
        _7 = (move _8,);
        _13 = copy (_7.0: &&str);
        _10 = core::fmt::rt::Argument::<'_>::new_display::<&str>(copy _13) -> [return: bb1, unwind unreachable];
    }

    bb1: {
        _9 = [move _10];
        _11 = const b"\x0cf128 -> i8: \xc0\x00";
        _12 = &_9;
        _6 = std::fmt::Arguments::<'_>::new::<15, 1>(move _11, copy _12) -> [return: bb2, unwind unreachable];
    }

    bb2: {
        _4 = floats::casts::assert_eq_msg::<i8, std::fmt::Arguments<'_>>(move _5, copy _2, move _6) -> [return: bb3, unwind unreachable];
    }

    bb3: {
        return;
    }
}

alloc45171 (size: 15, align: 1) {
    0c 66 31 32 38 20 2d 3e 20 69 38 3a 20 c0 00    │ .f128 -> i8: ..
}

error: VerifierErrors([VerifierError { location: inst7, context: Some("v6 = select.i32 v5, v4, v2  ; v4 = 255"), message: "arg 2 (v2) has type i8, expected i32" }])

error: cranelift verify error:
       function u0:773(f128) -> i8 system_v {
           sig0 = (f128) -> i8 system_v
           sig1 = (f128, f128) -> i32 system_v
           fn0 = u0:1968 sig0
           fn1 = u0:928 sig1
       
                                       block0(v0: f128):
                                           v1 -> v0
                                           nop 
                                           jump block1
       
                                       block1:
                                           nop 
       @0000                               v2 = call fn0(v1)
       @0000                               v3 = iconst.i32 0
       @0000                               v4 = iconst.i32 255
       @0000                               v5 = icmp_imm ugt v2, -1
       @0000                               v6 = select v5, v4, v2  ; v4 = 255
       ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       ; error: inst7 (v6 = select.i32 v5, v4, v2  ; v4 = 255): arg 2 (v2) has type i8, expected i32
       
       @0000                               v7 = ireduce.i8 v6
       @0000                               v8 = call fn1(v1, v1)
       @0000                               v9 = iconst.i32 0
       @0000                               v10 = icmp eq v8, v9  ; v9 = 0
       @0000                               v11 = iconst.i8 0
       @0000                               v12 = select v10, v7, v11  ; v11 = 0
                                           v13 -> v12
       @0000                               jump block2
       
                                       block2:
       @0000                               nop 
       @0001                               return v13
       }
       
       ; 1 verifier error detected (see above). Compilation aborted.
       

fn <f128 as std::convert::FloatToInt<u8>>::to_int_unchecked(_1: f128) -> u8 {
    debug self => _1;
    let mut _0: u8;

    bb0: {
        _0 = std::intrinsics::float_to_int_unchecked::<f128, u8>(move _1) -> [return: bb1, unwind unreachable];
    }

    bb1: {
        return;
    }
}

[RUSTC-TIMING] coretests test:true 65.662
error: could not compile `coretests` (test "coretests") due to 4 previous errors
env -u RUSTC_WRAPPER CARGO_ENCODED_RUSTDOCFLAGS="-Csymbol-mangling-version=v0\u{1f}-Zannotate-moves\u{1f}-Zrandomize-layout\u{1f}-Zunstable-options\u{1f}--check-cfg=cfg(bootstrap)\u{1f}-Wrustdoc::invalid_codeblock_attributes\u{1f}--crate-version\u{1f}1.95.0-nightly\t(deee2f05e\t2026-02-14)" CARGO_ENCODED_RUSTFLAGS="-Csymbol-mangling-version=v0\u{1f}-Zannotate-moves\u{1f}-Zrandomize-layout\u{1f}-Zunstable-options\u{1f}--check-cfg=cfg(bootstrap)\u{1f}-Zmacro-backtrace\u{1f}-Csplit-debuginfo=off\u{1f}-Clink-arg=-L/usr/lib/llvm-20/lib\u{1f}-Cllvm-args=-import-instr-limit=10\u{1f}-Clink-args=-Wl,-z,origin\u{1f}-Clink-args=-Wl,-rpath,$ORIGIN/../lib\u{1f}--cap-lints=allow\u{1f}--cfg\u{1f}randomized_layouts" RUSTC="/checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif/dist/rustc-clif" RUSTDOC="/checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif/dist/rustdoc-clif" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo" "test" "--manifest-path" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif/build/sysroot_tests/Cargo.toml" "--target-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif/build/sysroot_tests_target" "--locked" "--target" "aarch64-unknown-linux-gnu" "-p" "coretests" "-p" "alloctests" "--tests" "--" "-q" exited with status ExitStatus(unix_wait_status(25856))
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo run -Zwarnings --target aarch64-unknown-linux-gnu -Zbinary-dep-depinfo -j 4 -Zroot-dir=/checkout --locked --color=always --profile=release --manifest-path /checkout/compiler/rustc_codegen_cranelift/build_system/Cargo.toml -- test --download-dir /checkout/obj/build/cg_clif_download --out-dir /checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif --no-unstable-features --use-backend cranelift --sysroot llvm --skip-test testsuite.extended_sysroot [workdir=/checkout/compiler/rustc_codegen_cranelift]` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/test.rs:3877:25
Executed at: src/bootstrap/src/core/build_steps/test.rs:3922:26

Command has failed. Rerun with -v to see more details.
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 0:25:37
  local time: Sat Feb 14 01:07:00 UTC 2026
  network time: Sat, 14 Feb 2026 01:07:00 GMT
##[error]Process completed with exit code 1.

[okaneco]

My first exposure to the cranelift codebase was in the float constant PR, so I'm by no means an expert.

There was a change in that PR that you might want to cherry pick so it solves the separate f128->int casts issue c4582c8

For this CI failure, in the lib_call on line 220, should that to_ty be replaced with ret_ty in the third argument of the Vec? to_ty would still be an I8 if passed directly, but line 208 sets ret_ty to an I32.

rust/compiler/rustc_codegen_cranelift/src/codegen_f16_f128.rs

Lines 207 to 254 in a423f68

	} else if from_ty == types::F128 && to_ty.is_int() {
	let ret_ty = if to_ty.bits() < 32 { types::I32 } else { to_ty };
	let name = format!(
	"__fix{sign}tf{size}i",
	sign = if from_signed { "" } else { "un" },
	size = match ret_ty {
	types::I32 => 's',
	types::I64 => 'd',
	types::I128 => 't',
	_ => unreachable!("{from_ty:?}"),
	},
	);
	let ret =
	fx.lib_call(&name, vec![AbiParam::new(from_ty)], vec![AbiParam::new(to_ty)], &[from])
	[0];
	let val = if ret_ty == to_ty {
	ret
	} else {
	let (min, max) = match (to_ty, to_signed) {
	(types::I8, false) => (0, i64::from(u8::MAX)),
	(types::I16, false) => (0, i64::from(u16::MAX)),
	(types::I8, true) => (i64::from(i8::MIN as u32), i64::from(i8::MAX as u32)),
	(types::I16, true) => (i64::from(i16::MIN as u32), i64::from(i16::MAX as u32)),
	_ => unreachable!("{to_ty:?}"),
	};
	let min_val = fx.bcx.ins().iconst(types::I32, min);
	let max_val = fx.bcx.ins().iconst(types::I32, max);
	let val = if to_signed {
	let has_underflow = fx.bcx.ins().icmp_imm(IntCC::SignedLessThan, ret, min);
	let has_overflow = fx.bcx.ins().icmp_imm(IntCC::SignedGreaterThan, ret, max);
	let bottom_capped = fx.bcx.ins().select(has_underflow, min_val, ret);
	fx.bcx.ins().select(has_overflow, max_val, bottom_capped)
	} else {
	let has_overflow = fx.bcx.ins().icmp_imm(IntCC::UnsignedGreaterThan, ret, max);
	fx.bcx.ins().select(has_overflow, max_val, ret)
	};
	fx.bcx.ins().ireduce(to_ty, val)
	};
	if let Some(false) = fx.tcx.sess.opts.unstable_opts.saturating_float_casts {
	return val;
	}
	let is_not_nan = fcmp(fx, FloatCC::Equal, from, from);
	let zero = type_zero_value(&mut fx.bcx, to_ty);
	fx.bcx.ins().select(is_not_nan, val, zero)
	} else {