Auto merge of #222 - whitequark:master, r=alexcrichton

Implement comparesf2/comparedf2 intrinsics

These intrinsics are indeed called on soft-float targets, you can verify this by compiling:
```rust
#![no_std]
fn comparesf2(a: f32, b: f32) -> bool { a > b }
fn comparedf2(a: f64, b: f64) -> bool { a > b }
```
and looking at the disassembly.

Doesn't come with tests because I'm not about to write *fourteen* of these horrifying build.rs structs by hand, and also because `cargo test` fails on latest nightly.

README.md

@@ -52,16 +52,20 @@ features = ["c"]
 ## Contributing
 
 1. Pick one or more intrinsics from the [pending list](#progress).
-2. Fork this repository
-3. Port the intrinsic(s) and their corresponding [unit tests][1] from their [C implementation][2] to
-   Rust.
-4. Send a Pull Request (PR)
-5. Once the PR passes our extensive [testing infrastructure][3], we'll merge it!
+2. Fork this repository.
+3. Port the intrinsic(s) and their corresponding [unit tests][1] from their
+   [C implementation][2] to Rust.
+4. Implement a [test generator][3] to compare the behavior of the ported intrinsic(s)
+   with their implementation on the testing host. Note that randomized compiler-builtin tests
+   should be run using `cargo test --features gen-tests`.
+4. Send a Pull Request (PR).
+5. Once the PR passes our extensive [testing infrastructure][4], we'll merge it!
 6. Celebrate :tada:
 
 [1]: https://github.com/rust-lang/compiler-rt/tree/8598065bd965d9713bfafb6c1e766d63a7b17b89/test/builtins/Unit
 [2]: https://github.com/rust-lang/compiler-rt/tree/8598065bd965d9713bfafb6c1e766d63a7b17b89/lib/builtins
-[3]: https://travis-ci.org/rust-lang-nursery/compiler-builtins
+[3]: https://github.com/rust-lang-nursery/compiler-builtins/blob/0ba07e49264a54cb5bbd4856fcea083bb3fbec15/build.rs#L180-L265
+[4]: https://travis-ci.org/rust-lang-nursery/compiler-builtins
 
 ### Porting Reminders
 
@@ -133,6 +137,8 @@ features = ["c"]
 - [ ] arm/unordsf2vfp.S
 - [x] ashldi3.c
 - [x] ashrdi3.c
+- [x] comparedf2.c
+- [x] comparesf2.c
 - [x] divdf3.c
 - [x] divdi3.c
 - [x] divmoddi4.c
@@ -301,8 +307,6 @@ These builtins are never called by LLVM.
 - ~~clzti2.c~~
 - ~~cmpdi2.c~~
 - ~~cmpti2.c~~
-- ~~comparedf2.c~~
-- ~~comparesf2.c~~
 - ~~ctzdi2.c~~
 - ~~ctzsi2.c~~
 - ~~ctzti2.c~~

build.rs

@@ -89,6 +89,12 @@ mod tests {
             Adddf3,
             Addsf3,
 
+            // float/cmp.rs
+            Gedf2,
+            Gesf2,
+            Ledf2,
+            Lesf2,
+
             // float/conv.rs
             Fixdfdi,
             Fixdfsi,
@@ -2529,6 +2535,318 @@ fn floatuntidf() {
         }
     }
 
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct Gedf2 {
+        a: u64,
+        b: u64,
+        c: i32,
+    }
+
+    impl TestCase for Gedf2 {
+        fn name() -> &'static str {
+            "gedf2"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_f64(rng);
+            let b = gen_f64(rng);
+            // TODO accept NaNs. We don't do that right now because we can't check
+            // for NaN-ness on the thumb targets (due to missing intrinsics)
+            if a.is_nan() || b.is_nan() {
+                return None;
+            }
+
+            let c;
+            if a.is_nan() || b.is_nan() {
+                c = -1;
+            } else if a < b {
+                c = -1;
+            } else if a > b {
+                c = 1;
+            } else {
+                c = 0;
+            }
+
+            Some(Gedf2 { a: to_u64(a), b: to_u64(b), c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use std::mem;
+use compiler_builtins::float::cmp::__gedf2;
+
+fn to_f64(x: u64) -> f64 {
+    unsafe { mem::transmute(x) }
+}
+
+static TEST_CASES: &[((u64, u64), i32)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn gedf2() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = __gedf2(to_f64(a), to_f64(b));
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct Gesf2 {
+        a: u32,
+        b: u32,
+        c: i32,
+    }
+
+    impl TestCase for Gesf2 {
+        fn name() -> &'static str {
+            "gesf2"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_f32(rng);
+            let b = gen_f32(rng);
+            // TODO accept NaNs. We don't do that right now because we can't check
+            // for NaN-ness on the thumb targets (due to missing intrinsics)
+            if a.is_nan() || b.is_nan() {
+                return None;
+            }
+
+            let c;
+            if a.is_nan() || b.is_nan() {
+                c = -1;
+            } else if a < b {
+                c = -1;
+            } else if a > b {
+                c = 1;
+            } else {
+                c = 0;
+            }
+
+            Some(Gesf2 { a: to_u32(a), b: to_u32(b), c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use std::mem;
+use compiler_builtins::float::cmp::__gesf2;
+
+fn to_f32(x: u32) -> f32 {
+    unsafe { mem::transmute(x) }
+}
+
+static TEST_CASES: &[((u32, u32), i32)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn gesf2() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = __gesf2(to_f32(a), to_f32(b));
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct Ledf2 {
+        a: u64,
+        b: u64,
+        c: i32,
+    }
+
+    impl TestCase for Ledf2 {
+        fn name() -> &'static str {
+            "ledf2"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_f64(rng);
+            let b = gen_f64(rng);
+            // TODO accept NaNs. We don't do that right now because we can't check
+            // for NaN-ness on the thumb targets (due to missing intrinsics)
+            if a.is_nan() || b.is_nan() {
+                return None;
+            }
+
+            let c;
+            if a.is_nan() || b.is_nan() {
+                c = 1;
+            } else if a < b {
+                c = -1;
+            } else if a > b {
+                c = 1;
+            } else {
+                c = 0;
+            }
+
+            Some(Ledf2 { a: to_u64(a), b: to_u64(b), c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use std::mem;
+use compiler_builtins::float::cmp::__ledf2;
+
+fn to_f64(x: u64) -> f64 {
+    unsafe { mem::transmute(x) }
+}
+
+static TEST_CASES: &[((u64, u64), i32)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn ledf2() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = __ledf2(to_f64(a), to_f64(b));
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct Lesf2 {
+        a: u32,
+        b: u32,
+        c: i32,
+    }
+
+    impl TestCase for Lesf2 {
+        fn name() -> &'static str {
+            "lesf2"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_f32(rng);
+            let b = gen_f32(rng);
+            // TODO accept NaNs. We don't do that right now because we can't check
+            // for NaN-ness on the thumb targets (due to missing intrinsics)
+            if a.is_nan() || b.is_nan() {
+                return None;
+            }
+
+            let c;
+            if a.is_nan() || b.is_nan() {
+                c = 1;
+            } else if a < b {
+                c = -1;
+            } else if a > b {
+                c = 1;
+            } else {
+                c = 0;
+            }
+
+            Some(Lesf2 { a: to_u32(a), b: to_u32(b), c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use std::mem;
+use compiler_builtins::float::cmp::__lesf2;
+
+fn to_f32(x: u32) -> f32 {
+    unsafe { mem::transmute(x) }
+}
+
+static TEST_CASES: &[((u32, u32), i32)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn lesf2() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = __lesf2(to_f32(a), to_f32(b));
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
     #[derive(Eq, Hash, PartialEq)]
     pub struct Moddi3 {
         a: i64,
@@ -4982,8 +5300,6 @@ mod c {
                 "clzdi2.c",
                 "clzsi2.c",
                 "cmpdi2.c",
-                "comparedf2.c",
-                "comparesf2.c",
                 "ctzdi2.c",
                 "ctzsi2.c",
                 "divdc3.c",
@@ -5127,7 +5443,6 @@ mod c {
                     "arm/bswapsi2.S",
                     "arm/clzdi2.S",
                     "arm/clzsi2.S",
-                    "arm/comparesf2.S",
                     "arm/divmodsi4.S",
                     "arm/modsi3.S",
                     "arm/switch16.S",