Change float to integer tests to have an apfloat fallback

Author: tgross35

Diff for: README.md

@@ -239,12 +239,12 @@ These builtins are needed to support `f16` and `f128`, which are in the process
 - [x] extendhfsf2.c
 - [x] extendhftf2.c
 - [x] extendsftf2.c
-- [ ] fixtfdi.c
-- [ ] fixtfsi.c
-- [ ] fixtfti.c
-- [ ] fixunstfdi.c
-- [ ] fixunstfsi.c
-- [ ] fixunstfti.c
+- [x] fixtfdi.c
+- [x] fixtfsi.c
+- [x] fixtfti.c
+- [x] fixunstfdi.c
+- [x] fixunstfsi.c
+- [x] fixunstfti.c
 - [ ] floatditf.c
 - [ ] floatsitf.c
 - [ ] floatunditf.c

Diff for: build.rs

@@ -533,12 +533,6 @@ mod c {
         if (target_arch == "aarch64" || target_arch == "arm64ec") && consider_float_intrinsics {
             sources.extend(&[
                 ("__comparetf2", "comparetf2.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"),
@@ -561,9 +555,7 @@ mod c {
         if target_arch == "mips64" {
             sources.extend(&[
                 ("__netf2", "comparetf2.c"),
-                ("__fixtfsi", "fixtfsi.c"),
                 ("__floatsitf", "floatsitf.c"),
-                ("__fixunstfsi", "fixunstfsi.c"),
                 ("__floatunsitf", "floatunsitf.c"),
                 ("__fe_getround", "fp_mode.c"),
             ]);
@@ -572,9 +564,7 @@ mod c {
         if target_arch == "loongarch64" {
             sources.extend(&[
                 ("__netf2", "comparetf2.c"),
-                ("__fixtfsi", "fixtfsi.c"),
                 ("__floatsitf", "floatsitf.c"),
-                ("__fixunstfsi", "fixunstfsi.c"),
                 ("__floatunsitf", "floatunsitf.c"),
                 ("__fe_getround", "fp_mode.c"),
             ]);

Diff for: src/float/conv.rs

@@ -261,6 +261,21 @@ intrinsics! {
     pub extern "C" fn __fixunsdfti(f: f64) -> u128 {
         float_to_unsigned_int(f)
     }
+
+    #[cfg(not(feature = "no-f16-f128"))]
+    pub extern "C" fn __fixunstfsi(f: f128) -> u32 {
+        float_to_unsigned_int(f)
+    }
+
+    #[cfg(not(feature = "no-f16-f128"))]
+    pub extern "C" fn __fixunstfdi(f: f128) -> u64 {
+        float_to_unsigned_int(f)
+    }
+
+    #[cfg(not(feature = "no-f16-f128"))]
+    pub extern "C" fn __fixunstfti(f: f128) -> u128 {
+        float_to_unsigned_int(f)
+    }
 }
 
 // Conversions from floats to signed integers.
@@ -294,4 +309,19 @@ intrinsics! {
     pub extern "C" fn __fixdfti(f: f64) -> i128 {
         float_to_signed_int(f)
     }
+
+    #[cfg(not(feature = "no-f16-f128"))]
+    pub extern "C" fn __fixtfsi(f: f128) -> i32 {
+        float_to_signed_int(f)
+    }
+
+    #[cfg(not(feature = "no-f16-f128"))]
+    pub extern "C" fn __fixtfdi(f: f128) -> i64 {
+        float_to_signed_int(f)
+    }
+
+    #[cfg(not(feature = "no-f16-f128"))]
+    pub extern "C" fn __fixtfti(f: f128) -> i128 {
+        float_to_signed_int(f)
+    }
 }

Diff for: testcrate/Cargo.toml

@@ -34,4 +34,6 @@ no-f16-f128 = ["compiler_builtins/no-f16-f128"]
 mem = ["compiler_builtins/mem"]
 mangled-names = ["compiler_builtins/mangled-names"]
 # Skip tests that rely on f128 symbols being available on the system
-no-sys-f128 = []
+no-sys-f128 = ["no-sys-f128-int-convert"]
+# Some platforms have some f128 functions but everything except integer conversions
+no-sys-f128-int-convert = []

Diff for: testcrate/build.rs

@@ -1,7 +1,15 @@
-use std::env;
+use std::{collections::HashSet, env};
+
+/// Features to enable
+#[derive(Debug, PartialEq, Eq, Hash)]
+enum Feature {
+    NoSysF128,
+    NoSysF128IntConvert,
+}
 
 fn main() {
     let target = env::var("TARGET").unwrap();
+    let mut features = HashSet::new();
 
     // These platforms do not have f128 symbols available in their system libraries, so
     // skip related tests.
@@ -21,7 +29,24 @@ fn main() {
         // <https://github.com/rust-lang/compiler-builtins/pull/606#issuecomment-2105657287>.
         || target.starts_with("powerpc64-")
     {
-        println!("cargo:warning=using apfloat fallback for f128");
-        println!("cargo:rustc-cfg=feature=\"no-sys-f128\"");
+        features.insert(Feature::NoSysF128);
+        features.insert(Feature::NoSysF128IntConvert);
+    }
+
+    if target.starts_with("i586") || target.starts_with("i686") {
+        // 32-bit x86 seems to not have `__fixunstfti`, but does have everything else
+        features.insert(Feature::NoSysF128IntConvert);
+    }
+
+    for feature in features {
+        let (name, warning) = match feature {
+            Feature::NoSysF128 => ("no-sys-f128", "using apfloat fallback for f128"),
+            Feature::NoSysF128IntConvert => (
+                "no-sys-f128-int-convert",
+                "using apfloat fallback for f128 to int conversions",
+            ),
+        };
+        println!("cargo:warning={warning}");
+        println!("cargo:rustc-cfg=feature=\"{name}\"");
     }
 }

Diff for: testcrate/tests/conv.rs

@@ -100,14 +100,39 @@ mod f_to_i {
     use super::*;
 
     macro_rules! f_to_i {
-        ($x:ident, $($f:ty, $fn:ident);*;) => {
+        ($x:ident, $f_ty:ty, $apfloat_ty:ident, $sys_available:meta, $($i_ty:ty, $fn:ident);*;) => {
             $(
                 // it is undefined behavior in the first place to do conversions with NaNs
-                if !$x.is_nan() {
-                    let conv0 = $x as $f;
-                    let conv1: $f = $fn($x);
+                if !apfloat_fallback!(
+                    $f_ty, $apfloat_ty, $sys_available, |x: FloatTy| x.is_nan() => no_convert, $x
+                ) {
+                    let conv0 = apfloat_fallback!(
+                        $f_ty, $apfloat_ty, $sys_available,
+                        // Use an `as` cast when the builtin is available on the system.
+                        |x| x as $i_ty;
+                        // When the builtin is not available, we need to use a different conversion
+                        // method (since apfloat doesn't support `as` casting).
+                        |x: $f_ty| {
+                            use compiler_builtins::int::MinInt;
+
+                            let apf = FloatTy::from_bits(x.to_bits().into());
+                            let bits: usize = <$i_ty>::BITS.try_into().unwrap();
+
+                            let err_fn = || panic!(
+                                "Unable to convert value {x:?} to type {}:", stringify!($i_ty)
+                            );
+
+                            if <$i_ty>::SIGNED {
+                               <$i_ty>::try_from(apf.to_i128(bits).value).ok().unwrap_or_else(err_fn)
+                            } else {
+                               <$i_ty>::try_from(apf.to_u128(bits).value).ok().unwrap_or_else(err_fn)
+                            }
+                        },
+                        $x
+                    );
+                    let conv1: $i_ty = $fn($x);
                     if conv0 != conv1 {
-                        panic!("{}({}): std: {}, builtins: {}", stringify!($fn), $x, conv0, conv1);
+                        panic!("{}({:?}): std: {:?}, builtins: {:?}", stringify!($fn), $x, conv0, conv1);
                     }
                 }
             )*
@@ -121,7 +146,7 @@ mod f_to_i {
         };
 
         fuzz_float(N, |x: f32| {
-            f_to_i!(x,
+            f_to_i!(x, f32, Single, all(),
                 u32, __fixunssfsi;
                 u64, __fixunssfdi;
                 u128, __fixunssfti;
@@ -139,7 +164,7 @@ mod f_to_i {
         };
 
         fuzz_float(N, |x: f64| {
-            f_to_i!(x,
+            f_to_i!(x, f64, Double, all(),
                 u32, __fixunsdfsi;
                 u64, __fixunsdfdi;
                 u128, __fixunsdfti;
@@ -149,6 +174,29 @@ mod f_to_i {
             );
         });
     }
+
+    #[test]
+    #[cfg(not(feature = "no-f16-f128"))]
+    fn f128_to_int() {
+        use compiler_builtins::float::conv::{
+            __fixtfdi, __fixtfsi, __fixtfti, __fixunstfdi, __fixunstfsi, __fixunstfti,
+        };
+
+        fuzz_float(N, |x: f128| {
+            f_to_i!(
+                x,
+                f128,
+                Quad,
+                not(feature = "no-sys-f128-int-convert"),
+                u32, __fixunstfsi;
+                u64, __fixunstfdi;
+                u128, __fixunstfti;
+                i32, __fixtfsi;
+                i64, __fixtfdi;
+                i128, __fixtfti;
+            );
+        });
+    }
 }
 
 macro_rules! conv {