diff --git a/gcc-test-backend/src/main.rs b/gcc-test-backend/src/main.rs
index a5a28cb88a6..234c9563246 100644
--- a/gcc-test-backend/src/main.rs
+++ b/gcc-test-backend/src/main.rs
@@ -1,3 +1,5 @@
+#![feature(core_intrinsics)]
+
 fn i128_to_u64(u: i128) -> Option<u64> {
     let min = u64::MIN as i128;
     //let max = u64::MAX as i128;
@@ -16,7 +18,129 @@ fn i128_to_u64(u: i128) -> Option<u64> {
 }
 
 fn main() {
-    use std::convert::TryFrom;
+    /*test_float!(f64, f64, f64::INFINITY, f64::NEG_INFINITY, f64::NAN);
+    ($modname: ident, $fty: ty, $inf: expr, $neginf: expr, $nan: expr) => {*/
+
+    /*assert_eq!((0.0 as f64).min(0.0), 0.0);
+    assert!((0.0 as f64).min(0.0).is_sign_positive());
+    assert_eq!((-0.0 as f64).min(-0.0), -0.0);
+    assert!((-0.0 as f64).min(-0.0).is_sign_negative());
+    assert_eq!((9.0 as f64).min(9.0), 9.0);
+    assert_eq!((-9.0 as f64).min(0.0), -9.0);
+    assert_eq!((0.0 as f64).min(9.0), 0.0);
+    assert!((0.0 as f64).min(9.0).is_sign_positive());
+    assert_eq!((-0.0 as f64).min(9.0), -0.0);
+    assert!((-0.0 as f64).min(9.0).is_sign_negative());*/
+
+    //println!("{}", 9);
+    //println!("{}", 9.0_f32);
+    //assert_eq!(-9.0_f32, -9 as f32);
+
+    //assert_eq!("1", format!("{:.0}", 1.0f64));
+    //assert_eq!("9", format!("{:.0}", 9.4f64));
+    //assert_eq!("10", format!("{:.0}", 9.9f64));
+    //assert_eq!("9.8", format!("{:.1}", 9.849f64));
+    //assert_eq!("9.9", format!("{:.1}", 9.851f64));
+    //assert_eq!("1", format!("{:.0}", 0.5f64));
+
+    //assert_eq!(2.3f32.copysign(-1.0), -2.3f32);
+    /*let f = 9.4f32;
+    println!("{}", f);*/
+    //println!("{}", 9.4f32); // FIXME: this is using bytes_in_context(), but gives a wrong value.
+
+    /*extern {
+        //pub fn printf(format: *const i8, ...) -> i32;
+        pub fn printf(format: *const i8, arg: f64) -> i32;
+    }
+
+    unsafe {
+        printf(b"Num: %f\n\0" as *const _ as *const _, 9.4f64);
+    }
+    println!("{}", 9.4f64);*/
+
+    let mut value = 0;
+    let res = unsafe { std::intrinsics::atomic_cxchg(&mut value, 0, 1) };
+    println!("{:?}", res);
+    let res = unsafe { std::intrinsics::atomic_cxchg(&mut value, 0, 1) };
+    println!("{:?}", res);
+
+    use std::sync::atomic::{AtomicBool, Ordering};
+
+    let a = AtomicBool::new(false);
+    assert_eq!(a.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst), Ok(false));
+    assert_eq!(a.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst), Err(true));
+
+    a.store(false, Ordering::SeqCst);
+    assert_eq!(a.compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst), Ok(false));
+
+    // FIXME: the code seems to be the same when using an integer, but somehow, it doesn't work for
+    // a float. Could it be related to the fact that floating-points use different registers?
+
+    /*let f = 1234567.89f64;
+    assert_eq!("1.23456789e6", format!("{:e}", f));
+    println!("{:e}", f);
+    println!("{:e}", 1234567.89f64);*/
+    //assert_eq!("1.23456789e6", format!("{:e}", 1234567.89f64));
+    /*assert_eq!("1.23456789e3", format!("{:e}", 1234.56789f64));
+    assert_eq!("1.23456789E6", format!("{:E}", 1234567.89f64));
+    assert_eq!("1.23456789E3", format!("{:E}", 1234.56789f64));
+    assert_eq!("0.0", format!("{:?}", 0.0f64));
+    assert_eq!("1.01", format!("{:?}", 1.01f64));*/
+
+    /*assert_eq!((-0.0 as f64).min(-9.0), -9.0);
+    assert_eq!((f64::INFINITY as f64).min(9.0), 9.0);
+    assert_eq!((9.0 as f64).min(f64::INFINITY), 9.0);
+    assert_eq!((f64::INFINITY as f64).min(-9.0), -9.0);
+    assert_eq!((-9.0 as f64).min(f64::INFINITY), -9.0);
+    assert_eq!((f64::NEG_INFINITY as f64).min(9.0), f64::NEG_INFINITY);
+    assert_eq!((9.0 as f64).min(f64::NEG_INFINITY), f64::NEG_INFINITY);
+    assert_eq!((f64::NEG_INFINITY as f64).min(-9.0), f64::NEG_INFINITY);
+    assert_eq!((-9.0 as f64).min(f64::NEG_INFINITY), f64::NEG_INFINITY);*/
+    // Cranelift fmin has NaN propagation
+    //assert_eq!((f64::NAN as f64).min(9.0), 9.0);
+    //assert_eq!((f64::NAN as f64).min(-9.0), -9.0);
+    //assert_eq!((9.0 as f64).min(f64::NAN), 9.0);
+    //assert_eq!((-9.0 as f64).min(f64::NAN), -9.0);
+    //assert!((f64::NAN as f64).min(f64::NAN).is_nan());
+
+    /*let max: f64 = f32::MAX.into();
+    assert_eq!(max as f32, f32::MAX);
+    assert!(max.is_normal());
+
+    let min: f64 = f32::MIN.into();
+    assert_eq!(min as f32, f32::MIN);
+    assert!(min.is_normal());
+
+    let min_positive: f64 = f32::MIN_POSITIVE.into();
+    assert_eq!(min_positive as f32, f32::MIN_POSITIVE);
+    assert!(min_positive.is_normal());
+
+    let epsilon: f64 = f32::EPSILON.into();
+    assert_eq!(epsilon as f32, f32::EPSILON);
+    assert!(epsilon.is_normal());
+
+    let zero: f64 = (0.0f32).into();
+    assert_eq!(zero as f32, 0.0f32);
+    assert!(zero.is_sign_positive());
+
+    let neg_zero: f64 = (-0.0f32).into();
+    assert_eq!(neg_zero as f32, -0.0f32);
+    assert!(neg_zero.is_sign_negative());
+
+    let infinity: f64 = f32::INFINITY.into();
+    assert_eq!(infinity as f32, f32::INFINITY);
+    assert!(infinity.is_infinite());
+    assert!(infinity.is_sign_positive());
+
+    let neg_infinity: f64 = f32::NEG_INFINITY.into();
+    assert_eq!(neg_infinity as f32, f32::NEG_INFINITY);
+    assert!(neg_infinity.is_infinite());
+    assert!(neg_infinity.is_sign_negative());
+
+    let nan: f64 = f32::NAN.into();
+    assert!(nan.is_nan());*/
+
+    /*use std::convert::TryFrom;
 
     /*let max = <i128>::MAX;
     let min = <i128>::MIN;*/
@@ -35,4 +159,5 @@ fn main() {
         <u64 as TryFrom<i128>>::try_from(t_min as i128).unwrap(),
         t_min as u64
     );*/
+    */
 }
diff --git a/src/builder.rs b/src/builder.rs
index e12184a8931..94ea7a01c9b 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -123,7 +123,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
             };
 
         let cond1 = self.context.new_comparison(None, comparison_operator, previous_var.to_rvalue(), self.context.new_cast(None, src, previous_value.get_type()));
-        let compare_exchange = self.compare_exchange(dst, previous_var.to_rvalue(), src, order, load_ordering, false);
+        let compare_exchange = self.compare_exchange(dst, previous_var, src, order, load_ordering, false);
         let cond2 = self.cx.context.new_unary_op(None, UnaryOp::LogicalNegate, compare_exchange.get_type(), compare_exchange);
         let cond = self.cx.context.new_binary_op(None, BinaryOp::LogicalAnd, self.cx.bool_type, cond1, cond2);
 
@@ -137,7 +137,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         return_value.to_rvalue()
     }
 
-    fn compare_exchange(&self, dst: RValue<'gcc>, cmp: RValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering, failure_order: AtomicOrdering, weak: bool) -> RValue<'gcc> {
+    fn compare_exchange(&self, dst: RValue<'gcc>, cmp: LValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering, failure_order: AtomicOrdering, weak: bool) -> RValue<'gcc> {
         let size = self.cx.int_width(src.get_type());
         let compare_exchange = self.context.get_builtin_function(&format!("__atomic_compare_exchange_{}", size / 8));
         let order = self.context.new_rvalue_from_int(self.i32_type, order.to_gcc());
@@ -147,9 +147,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
         let void_ptr_type = self.context.new_type::<*mut ()>();
         let volatile_void_ptr_type = void_ptr_type.make_volatile();
         let dst = self.context.new_cast(None, dst, volatile_void_ptr_type);
-        let expected = self.current_func().new_local(None, cmp.get_type(), "expected");
-        self.llbb().add_assignment(None, expected, cmp);
-        let expected = self.context.new_cast(None, expected.get_address(None), void_ptr_type);
+        let expected = self.context.new_cast(None, cmp.get_address(None), void_ptr_type);
 
         // NOTE: not sure why, but we need to cast to the signed type.
         let new_src_type =
@@ -1494,7 +1492,9 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
     // Atomic Operations
     fn atomic_cmpxchg(&mut self, dst: RValue<'gcc>, cmp: RValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering, failure_order: AtomicOrdering, weak: bool) -> RValue<'gcc> {
-        let success = self.compare_exchange(dst, cmp, src, order, failure_order, weak);
+        let expected = self.current_func().new_local(None, cmp.get_type(), "expected");
+        self.llbb().add_assignment(None, expected, cmp);
+        let success = self.compare_exchange(dst, expected, src, order, failure_order, weak);
 
         let pair_type = self.cx.type_struct(&[src.get_type(), self.bool_type], false);
         let result = self.current_func().new_local(None, pair_type, "atomic_cmpxchg_result");
@@ -1502,9 +1502,12 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
         let value_type = result.to_rvalue().get_type();
         if let Some(struct_type) = value_type.is_struct() {
-            self.store(cmp, result.access_field(None, struct_type.get_field(0)).get_address(None), align);
             self.store(success, result.access_field(None, struct_type.get_field(1)).get_address(None), align);
+            // NOTE: since success contains the call to the intrinsic, it must be stored before
+            // expected so that we store expected after the call.
+            self.store(expected.to_rvalue(), result.access_field(None, struct_type.get_field(0)).get_address(None), align);
         }
+        // TODO: handle when value is not a struct.
 
         result.to_rvalue()
     }