From 534d22e2871740579c0cf89ec476f6b3a09d7e26 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Fri, 30 Sep 2016 17:30:05 -0500
Subject: [PATCH 1/6] panic! -> abort

closes #79
---
 src/int/udiv.rs | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/int/udiv.rs b/src/int/udiv.rs
index 3de18b4..8a9da9f 100644
--- a/src/int/udiv.rs
+++ b/src/int/udiv.rs
@@ -1,4 +1,4 @@
-use core::mem;
+use core::{intrinsics, mem};
 use int::{Int, LargeInt};
 
 /// Returns `n / d`
@@ -7,7 +7,11 @@ use int::{Int, LargeInt};
 pub extern "C" fn __udivsi3(n: u32, d: u32) -> u32 {
     // Special cases
     if d == 0 {
-        panic!("Division by zero");
+        // NOTE This should be unreachable in safe Rust because the program will panic before
+        // this intrinsic is called
+        unsafe {
+            intrinsics::abort()
+        }
     }
 
     if n == 0 {
@@ -129,7 +133,11 @@ pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
             // K X
             // ---
             // 0 0
-            panic!("Division by zero");
+            // NOTE This should be unreachable in safe Rust because the program will panic before
+            // this intrinsic is called
+            unsafe {
+                intrinsics::abort()
+            }
         }
 
         if n.low() == 0 {

From a2ffc799d065155de70cf08ee45c6a3333b365e8 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Fri, 30 Sep 2016 23:10:30 -0500
Subject: [PATCH 2/6] check that we don't have any call to panic in our
 implementations

---
 Cargo.toml            |   3 ++
 ci/run.sh             |  10 ++++
 src/bin/intrinsics.rs | 106 ++++++++++++++++++++++++------------------
 3 files changed, 75 insertions(+), 44 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index c198d9f..b3a5cf4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,3 +26,6 @@ c = []
 weak = ["rlibc/weak"]
 
 [workspace]
+
+[profile.release]
+lto = true
diff --git a/ci/run.sh b/ci/run.sh
index 7dc9be1..6a0906b 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -28,6 +28,16 @@ case $1 in
         ;;
 esac
 
+# Verify that there are no undefined symbols to `panic` within our implementations
+case $1 in
+    thumb*)
+        xargo build --features c --target $1 --bin intrinsics --release
+        ;;
+    *)
+        cargo build --features c --target $1 --bin intrinsics --release
+        ;;
+esac
+
 # Look out for duplicated symbols when we include the compiler-rt (C) implementation
 PREFIX=$(echo $1 | sed -e 's/unknown-//')-
 case $1 in
diff --git a/src/bin/intrinsics.rs b/src/bin/intrinsics.rs
index 5e23485..591765a 100644
--- a/src/bin/intrinsics.rs
+++ b/src/bin/intrinsics.rs
@@ -302,52 +302,70 @@ mod intrinsics {
 
 #[cfg(feature = "c")]
 fn run() {
+    use core::ptr;
     use intrinsics::*;
 
-    aeabi_d2f(2.);
-    aeabi_d2i(2.);
-    aeabi_d2l(2.);
-    aeabi_d2uiz(2.);
-    aeabi_d2ulz(2.);
-    aeabi_dadd(2., 3.);
-    aeabi_dcmpeq(2., 3.);
-    aeabi_dcmpgt(2., 3.);
-    aeabi_dcmplt(2., 3.);
-    aeabi_ddiv(2., 3.);
-    aeabi_dmul(2., 3.);
-    aeabi_dsub(2., 3.);
-    aeabi_f2d(2.);
-    aeabi_f2iz(2.);
-    aeabi_f2lz(2.);
-    aeabi_f2uiz(2.);
-    aeabi_f2ulz(2.);
-    aeabi_fadd(2., 3.);
-    aeabi_fcmpeq(2., 3.);
-    aeabi_fcmpgt(2., 3.);
-    aeabi_fcmplt(2., 3.);
-    aeabi_fdiv(2., 3.);
-    aeabi_fmul(2., 3.);
-    aeabi_fsub(2., 3.);
-    aeabi_i2d(2);
-    aeabi_i2f(2);
-    aeabi_idiv(2, 3);
-    aeabi_idivmod(2, 3);
-    aeabi_l2d(2);
-    aeabi_l2f(2);
-    aeabi_ldivmod(2, 3);
-    aeabi_lmul(2, 3);
-    aeabi_ui2d(2);
-    aeabi_ui2f(2);
-    aeabi_uidiv(2, 3);
-    aeabi_uidivmod(2, 3);
-    aeabi_ul2d(2);
-    aeabi_ul2f(2);
-    aeabi_uldivmod(2, 3);
-    moddi3(2, 3);
-    mulodi4(2, 3);
-    powidf2(2., 3);
-    powisf2(2., 3);
-    umoddi3(2, 3);
+    // We use volatile load/stores to prevent LLVM from optimizing away the intrinsics during LTO
+    macro_rules! arg {
+        () => {
+            unsafe {
+                ptr::read_volatile(0x0 as *const _)
+            }
+        }
+    }
+
+    macro_rules! ret {
+        ($e:expr) => {
+            unsafe {
+                ptr::write_volatile(0x0 as *mut _, $e)
+            }
+        }
+    }
+
+    ret!(aeabi_d2f(arg!()));
+    ret!(aeabi_d2i(arg!()));
+    ret!(aeabi_d2l(arg!()));
+    ret!(aeabi_d2uiz(arg!()));
+    ret!(aeabi_d2ulz(arg!()));
+    ret!(aeabi_dadd(arg!(), arg!()));
+    ret!(aeabi_dcmpeq(arg!(), arg!()));
+    ret!(aeabi_dcmpgt(arg!(), arg!()));
+    ret!(aeabi_dcmplt(arg!(), arg!()));
+    ret!(aeabi_ddiv(arg!(), arg!()));
+    ret!(aeabi_dmul(arg!(), arg!()));
+    ret!(aeabi_dsub(arg!(), arg!()));
+    ret!(aeabi_f2d(arg!()));
+    ret!(aeabi_f2iz(arg!()));
+    ret!(aeabi_f2lz(arg!()));
+    ret!(aeabi_f2uiz(arg!()));
+    ret!(aeabi_f2ulz(arg!()));
+    ret!(aeabi_fadd(arg!(), arg!()));
+    ret!(aeabi_fcmpeq(arg!(), arg!()));
+    ret!(aeabi_fcmpgt(arg!(), arg!()));
+    ret!(aeabi_fcmplt(arg!(), arg!()));
+    ret!(aeabi_fdiv(arg!(), arg!()));
+    ret!(aeabi_fmul(arg!(), arg!()));
+    ret!(aeabi_fsub(arg!(), arg!()));
+    ret!(aeabi_i2d(arg!()));
+    ret!(aeabi_i2f(arg!()));
+    ret!(aeabi_idiv(arg!(), arg!()));
+    ret!(aeabi_idivmod(arg!(), arg!()));
+    ret!(aeabi_l2d(arg!()));
+    ret!(aeabi_l2f(arg!()));
+    ret!(aeabi_ldivmod(arg!(), arg!()));
+    ret!(aeabi_lmul(arg!(), arg!()));
+    ret!(aeabi_ui2d(arg!()));
+    ret!(aeabi_ui2f(arg!()));
+    ret!(aeabi_uidiv(arg!(), arg!()));
+    ret!(aeabi_uidivmod(arg!(), arg!()));
+    ret!(aeabi_ul2d(arg!()));
+    ret!(aeabi_ul2f(arg!()));
+    ret!(aeabi_uldivmod(arg!(), arg!()));
+    ret!(moddi3(arg!(), arg!()));
+    ret!(mulodi4(arg!(), arg!()));
+    ret!(powidf2(arg!(), arg!()));
+    ret!(powisf2(arg!(), arg!()));
+    ret!(umoddi3(arg!(), arg!()));
 }
 
 #[cfg(all(feature = "c", not(thumb)))]

From a21fb956f99232da08c16ef643bcb10175289667 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Wed, 5 Oct 2016 20:45:40 -0500
Subject: [PATCH 3/6] insert more `abort()` calls where division by zero may
 occur

---
 src/int/sdiv.rs | 14 ++++++++++++++
 src/int/udiv.rs |  8 ++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/int/sdiv.rs b/src/int/sdiv.rs
index 37f5dd7..d60dda9 100644
--- a/src/int/sdiv.rs
+++ b/src/int/sdiv.rs
@@ -1,3 +1,5 @@
+use core::intrinsics;
+
 use int::Int;
 
 macro_rules! div {
@@ -10,6 +12,12 @@ macro_rules! div {
             let a = (a ^ s_a) - s_a;
             let b = (b ^ s_b) - s_b;
             let s = s_a ^ s_b;
+
+            if b == 0 {
+                unsafe {
+                    intrinsics::abort()
+                }
+            }
             let r = (a as $uty) / (b as $uty);
             (r as $ty ^ s) - s
         }
@@ -25,6 +33,12 @@ macro_rules! mod_ {
             let b = (b ^ s) - s;
             let s = a >> (<$ty>::bits() - 1);
             let a = (a ^ s) - s;
+
+            if b == 0 {
+                unsafe {
+                    intrinsics::abort()
+                }
+            }
             let r = (a as $uty) % (b as $uty);
             (r as $ty ^ s) - s
         }
diff --git a/src/int/udiv.rs b/src/int/udiv.rs
index 8a9da9f..bb1546c 100644
--- a/src/int/udiv.rs
+++ b/src/int/udiv.rs
@@ -109,6 +109,14 @@ pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
             // 0 X
             // ---
             // 0 X
+            // NOTE This should be unreachable in safe Rust because the program will panic before
+            // this intrinsic is called
+            if d.low() == 0 {
+                unsafe {
+                    intrinsics::abort()
+                }
+            }
+
             if let Some(rem) = rem {
                 *rem = u64::from(n.low() % d.low());
             }

From fd69beba295595e1ba5f70a893835ba4d187d716 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Fri, 7 Oct 2016 10:17:44 -0500
Subject: [PATCH 4/6] get profile.dev (-debug-assertions) + LTO working

---
 Cargo.toml       |  6 ++---
 ci/run.sh        |  6 +++--
 src/float/pow.rs |  5 ++--
 src/int/sdiv.rs  | 14 ++---------
 src/int/udiv.rs  | 15 ++++--------
 src/lib.rs       | 60 ++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 76 insertions(+), 30 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index b3a5cf4..eefb0b2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,7 +25,7 @@ compiler-rt = { path = "compiler-rt" }
 c = []
 weak = ["rlibc/weak"]
 
-[workspace]
+[profile.dev]
+debug-assertions = false
 
-[profile.release]
-lto = true
+[workspace]
diff --git a/ci/run.sh b/ci/run.sh
index 6a0906b..df27e35 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -31,10 +31,12 @@ esac
 # Verify that there are no undefined symbols to `panic` within our implementations
 case $1 in
     thumb*)
-        xargo build --features c --target $1 --bin intrinsics --release
+        xargo rustc --features c --target $1 --bin intrinsics -- -C lto
+        xargo rustc --features c --target $1 --bin intrinsics --release -- -C lto
         ;;
     *)
-        cargo build --features c --target $1 --bin intrinsics --release
+        cargo rustc --features c --target $1 --bin intrinsics -- -C lto
+        cargo rustc --features c --target $1 --bin intrinsics --release -- -C lto
         ;;
 esac
 
diff --git a/src/float/pow.rs b/src/float/pow.rs
index 14b3b9a..c02c76f 100644
--- a/src/float/pow.rs
+++ b/src/float/pow.rs
@@ -1,6 +1,7 @@
+use core::intrinsics;
 
 macro_rules! pow {
-    ($intrinsic:ident: $fty:ty, $ity:ty) => {
+    ($intrinsic:ident: $fty:ty, $ity:ident) => {
         /// Returns `a` raised to the power `b`
         #[cfg_attr(not(test), no_mangle)]
         pub extern "C" fn $intrinsic(a: $fty, b: $ity) -> $fty {
@@ -11,7 +12,7 @@ macro_rules! pow {
                 if (b & 1) != 0 {
                     r *= a;
                 }
-                b /= 2;
+                b = sdiv!($ity, b, 2);
                 if b == 0 {
                     break;
                 }
diff --git a/src/int/sdiv.rs b/src/int/sdiv.rs
index d60dda9..6f96b80 100644
--- a/src/int/sdiv.rs
+++ b/src/int/sdiv.rs
@@ -13,12 +13,7 @@ macro_rules! div {
             let b = (b ^ s_b) - s_b;
             let s = s_a ^ s_b;
 
-            if b == 0 {
-                unsafe {
-                    intrinsics::abort()
-                }
-            }
-            let r = (a as $uty) / (b as $uty);
+            let r = udiv!((a as $uty), (b as $uty));
             (r as $ty ^ s) - s
         }
     }
@@ -34,12 +29,7 @@ macro_rules! mod_ {
             let s = a >> (<$ty>::bits() - 1);
             let a = (a ^ s) - s;
 
-            if b == 0 {
-                unsafe {
-                    intrinsics::abort()
-                }
-            }
-            let r = (a as $uty) % (b as $uty);
+            let r = urem!((a as $uty), (b as $uty));
             (r as $ty ^ s) - s
         }
     }
diff --git a/src/int/udiv.rs b/src/int/udiv.rs
index bb1546c..999dcec 100644
--- a/src/int/udiv.rs
+++ b/src/int/udiv.rs
@@ -109,18 +109,11 @@ pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
             // 0 X
             // ---
             // 0 X
-            // NOTE This should be unreachable in safe Rust because the program will panic before
-            // this intrinsic is called
-            if d.low() == 0 {
-                unsafe {
-                    intrinsics::abort()
-                }
-            }
 
             if let Some(rem) = rem {
-                *rem = u64::from(n.low() % d.low());
+                *rem = u64::from(urem!(n.low(), d.low()));
             }
-            return u64::from(n.low() / d.low());
+            return u64::from(udiv!(n.low(), d.low()));
         } else {
             // 0 X
             // ---
@@ -153,9 +146,9 @@ pub extern "C" fn __udivmoddi4(n: u64, d: u64, rem: Option<&mut u64>) -> u64 {
             // ---
             // K 0
             if let Some(rem) = rem {
-                *rem = u64::from_parts(0, n.high() % d.high());
+                *rem = u64::from_parts(0, urem!(n.high(), d.high()));
             }
-            return u64::from(n.high() / d.high());
+            return u64::from(udiv!(n.high(), d.high()));
         }
 
         // K K
diff --git a/src/lib.rs b/src/lib.rs
index acc56c9..351be02 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,66 @@
 // NOTE cfg(all(feature = "c", ..)) indicate that compiler-rt provides an arch optimized
 // implementation of that intrinsic and we'll prefer to use that
 
+macro_rules! udiv {
+    ($a:expr, $b:expr) => {
+        unsafe {
+            let a = $a;
+            let b = $b;
+
+            if b == 0 {
+                intrinsics::abort()
+            } else {
+                intrinsics::unchecked_div(a, b)
+            }
+        }
+    }
+}
+
+macro_rules! sdiv {
+    ($sty:ident, $a:expr, $b:expr) => {
+        unsafe {
+            let a = $a;
+            let b = $b;
+
+            if b == 0 || (b == -1 && a == $sty::min_value()) {
+                intrinsics::abort()
+            } else {
+                intrinsics::unchecked_div(a, b)
+            }
+        }
+    }
+}
+
+macro_rules! urem {
+    ($a:expr, $b:expr) => {
+        unsafe {
+            let a = $a;
+            let b = $b;
+
+            if b == 0 {
+                intrinsics::abort()
+            } else {
+                intrinsics::unchecked_rem(a, b)
+            }
+        }
+    }
+}
+
+macro_rules! srem {
+    ($sty:ty, $a:expr, $b:expr) => {
+        unsafe {
+            let a = $a;
+            let b = $b;
+
+            if b == 0 || (b == -1 && a == $sty::min_value()) {
+                intrinsics::abort()
+            } else {
+                intrinsics::unchecked_rem(a, b)
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 #[macro_use]
 extern crate quickcheck;

From c82403551d7093d1c50dc0167025741621038014 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Fri, 7 Oct 2016 17:48:37 -0500
Subject: [PATCH 5/6] fix unsafe warnings

---
 Cargo.toml            |  3 ---
 ci/run.sh             |  5 +++--
 src/bin/intrinsics.rs |  4 +---
 src/float/mod.rs      |  1 +
 src/float/pow.rs      |  2 --
 src/int/sdiv.rs       |  6 ++----
 src/lib.rs            | 17 +++++++++--------
 7 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index eefb0b2..c198d9f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,7 +25,4 @@ compiler-rt = { path = "compiler-rt" }
 c = []
 weak = ["rlibc/weak"]
 
-[profile.dev]
-debug-assertions = false
-
 [workspace]
diff --git a/ci/run.sh b/ci/run.sh
index df27e35..0ac9d68 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -29,13 +29,14 @@ case $1 in
 esac
 
 # Verify that there are no undefined symbols to `panic` within our implementations
+# TODO(#79) fix the undefined references problem for debug-assertions+lto
 case $1 in
     thumb*)
-        xargo rustc --features c --target $1 --bin intrinsics -- -C lto
+        RUSTFLAGS="-C debug-assertions=no" xargo rustc --features c --target $1 --bin intrinsics -- -C lto
         xargo rustc --features c --target $1 --bin intrinsics --release -- -C lto
         ;;
     *)
-        cargo rustc --features c --target $1 --bin intrinsics -- -C lto
+        RUSTFLAGS="-C debug-assertions=no" cargo rustc --features c --target $1 --bin intrinsics -- -C lto
         cargo rustc --features c --target $1 --bin intrinsics --release -- -C lto
         ;;
 esac
diff --git a/src/bin/intrinsics.rs b/src/bin/intrinsics.rs
index 591765a..ca01a9d 100644
--- a/src/bin/intrinsics.rs
+++ b/src/bin/intrinsics.rs
@@ -308,9 +308,7 @@ fn run() {
     // We use volatile load/stores to prevent LLVM from optimizing away the intrinsics during LTO
     macro_rules! arg {
         () => {
-            unsafe {
-                ptr::read_volatile(0x0 as *const _)
-            }
+            ptr::read_volatile(0x0 as *const _)
         }
     }
 
diff --git a/src/float/mod.rs b/src/float/mod.rs
index 8bd574d..7dc084d 100644
--- a/src/float/mod.rs
+++ b/src/float/mod.rs
@@ -1,4 +1,5 @@
 use core::mem;
+#[cfg(test)]
 use core::fmt;
 
 pub mod add;
diff --git a/src/float/pow.rs b/src/float/pow.rs
index c02c76f..838805f 100644
--- a/src/float/pow.rs
+++ b/src/float/pow.rs
@@ -1,5 +1,3 @@
-use core::intrinsics;
-
 macro_rules! pow {
     ($intrinsic:ident: $fty:ty, $ity:ident) => {
         /// Returns `a` raised to the power `b`
diff --git a/src/int/sdiv.rs b/src/int/sdiv.rs
index 6f96b80..a1d119f 100644
--- a/src/int/sdiv.rs
+++ b/src/int/sdiv.rs
@@ -1,5 +1,3 @@
-use core::intrinsics;
-
 use int::Int;
 
 macro_rules! div {
@@ -13,7 +11,7 @@ macro_rules! div {
             let b = (b ^ s_b) - s_b;
             let s = s_a ^ s_b;
 
-            let r = udiv!((a as $uty), (b as $uty));
+            let r = udiv!(a as $uty, b as $uty);
             (r as $ty ^ s) - s
         }
     }
@@ -29,7 +27,7 @@ macro_rules! mod_ {
             let s = a >> (<$ty>::bits() - 1);
             let a = (a ^ s) - s;
 
-            let r = urem!((a as $uty), (b as $uty));
+            let r = urem!(a as $uty, b as $uty);
             (r as $ty ^ s) - s
         }
     }
diff --git a/src/lib.rs b/src/lib.rs
index 351be02..f5a12af 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,7 @@
 // NOTE cfg(all(feature = "c", ..)) indicate that compiler-rt provides an arch optimized
 // implementation of that intrinsic and we'll prefer to use that
 
+// TODO(rust-lang/rust#37029) use e.g. checked_div(_).unwrap_or_else(|| abort())
 macro_rules! udiv {
     ($a:expr, $b:expr) => {
         unsafe {
@@ -20,9 +21,9 @@ macro_rules! udiv {
             let b = $b;
 
             if b == 0 {
-                intrinsics::abort()
+                ::core::intrinsics::abort()
             } else {
-                intrinsics::unchecked_div(a, b)
+                ::core::intrinsics::unchecked_div(a, b)
             }
         }
     }
@@ -35,9 +36,9 @@ macro_rules! sdiv {
             let b = $b;
 
             if b == 0 || (b == -1 && a == $sty::min_value()) {
-                intrinsics::abort()
+                ::core::intrinsics::abort()
             } else {
-                intrinsics::unchecked_div(a, b)
+                ::core::intrinsics::unchecked_div(a, b)
             }
         }
     }
@@ -50,9 +51,9 @@ macro_rules! urem {
             let b = $b;
 
             if b == 0 {
-                intrinsics::abort()
+                ::core::intrinsics::abort()
             } else {
-                intrinsics::unchecked_rem(a, b)
+                ::core::intrinsics::unchecked_rem(a, b)
             }
         }
     }
@@ -65,9 +66,9 @@ macro_rules! srem {
             let b = $b;
 
             if b == 0 || (b == -1 && a == $sty::min_value()) {
-                intrinsics::abort()
+                ::core::intrinsics::abort()
             } else {
-                intrinsics::unchecked_rem(a, b)
+                ::core::intrinsics::unchecked_rem(a, b)
             }
         }
     }

From 96ddd4ed8d3e8ab0dcf050641171789b7eb41f0f Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Fri, 7 Oct 2016 18:26:21 -0500
Subject: [PATCH 6/6] use test::black_box instead of ptr::*_volatile

both prevent LLVM from optimizing away the intrinsics but the former
doesn't produce an `intrinsics` binary that segfaults
---
 ci/run.sh             |   2 +-
 src/bin/intrinsics.rs | 109 +++++++++++++++++++-----------------------
 2 files changed, 51 insertions(+), 60 deletions(-)

diff --git a/ci/run.sh b/ci/run.sh
index 0ac9d68..3846049 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -32,7 +32,7 @@ esac
 # TODO(#79) fix the undefined references problem for debug-assertions+lto
 case $1 in
     thumb*)
-        RUSTFLAGS="-C debug-assertions=no" xargo rustc --features c --target $1 --bin intrinsics -- -C lto
+        RUSTFLAGS="-C debug-assertions=no -C link-arg=-nostartfiles" xargo rustc --features c --target $1 --bin intrinsics -- -C lto
         xargo rustc --features c --target $1 --bin intrinsics --release -- -C lto
         ;;
     *)
diff --git a/src/bin/intrinsics.rs b/src/bin/intrinsics.rs
index ca01a9d..e11e415 100644
--- a/src/bin/intrinsics.rs
+++ b/src/bin/intrinsics.rs
@@ -4,13 +4,14 @@
 // to link due to the missing intrinsic (symbol).
 
 #![allow(unused_features)]
+#![cfg_attr(thumb, no_main)]
 #![deny(dead_code)]
+#![feature(asm)]
 #![feature(core_float)]
 #![feature(lang_items)]
 #![feature(libc)]
 #![feature(start)]
 #![no_std]
-#![cfg_attr(thumb, no_main)]
 
 #[cfg(not(thumb))]
 extern crate libc;
@@ -302,68 +303,58 @@ mod intrinsics {
 
 #[cfg(feature = "c")]
 fn run() {
-    use core::ptr;
     use intrinsics::*;
 
-    // We use volatile load/stores to prevent LLVM from optimizing away the intrinsics during LTO
-    macro_rules! arg {
-        () => {
-            ptr::read_volatile(0x0 as *const _)
-        }
+    // A copy of "test::black_box". Used to prevent LLVM from optimizing away the intrinsics during LTO
+    fn bb<T>(dummy: T) -> T {
+        unsafe { asm!("" : : "r"(&dummy)) }
+        dummy
     }
 
-    macro_rules! ret {
-        ($e:expr) => {
-            unsafe {
-                ptr::write_volatile(0x0 as *mut _, $e)
-            }
-        }
-    }
-
-    ret!(aeabi_d2f(arg!()));
-    ret!(aeabi_d2i(arg!()));
-    ret!(aeabi_d2l(arg!()));
-    ret!(aeabi_d2uiz(arg!()));
-    ret!(aeabi_d2ulz(arg!()));
-    ret!(aeabi_dadd(arg!(), arg!()));
-    ret!(aeabi_dcmpeq(arg!(), arg!()));
-    ret!(aeabi_dcmpgt(arg!(), arg!()));
-    ret!(aeabi_dcmplt(arg!(), arg!()));
-    ret!(aeabi_ddiv(arg!(), arg!()));
-    ret!(aeabi_dmul(arg!(), arg!()));
-    ret!(aeabi_dsub(arg!(), arg!()));
-    ret!(aeabi_f2d(arg!()));
-    ret!(aeabi_f2iz(arg!()));
-    ret!(aeabi_f2lz(arg!()));
-    ret!(aeabi_f2uiz(arg!()));
-    ret!(aeabi_f2ulz(arg!()));
-    ret!(aeabi_fadd(arg!(), arg!()));
-    ret!(aeabi_fcmpeq(arg!(), arg!()));
-    ret!(aeabi_fcmpgt(arg!(), arg!()));
-    ret!(aeabi_fcmplt(arg!(), arg!()));
-    ret!(aeabi_fdiv(arg!(), arg!()));
-    ret!(aeabi_fmul(arg!(), arg!()));
-    ret!(aeabi_fsub(arg!(), arg!()));
-    ret!(aeabi_i2d(arg!()));
-    ret!(aeabi_i2f(arg!()));
-    ret!(aeabi_idiv(arg!(), arg!()));
-    ret!(aeabi_idivmod(arg!(), arg!()));
-    ret!(aeabi_l2d(arg!()));
-    ret!(aeabi_l2f(arg!()));
-    ret!(aeabi_ldivmod(arg!(), arg!()));
-    ret!(aeabi_lmul(arg!(), arg!()));
-    ret!(aeabi_ui2d(arg!()));
-    ret!(aeabi_ui2f(arg!()));
-    ret!(aeabi_uidiv(arg!(), arg!()));
-    ret!(aeabi_uidivmod(arg!(), arg!()));
-    ret!(aeabi_ul2d(arg!()));
-    ret!(aeabi_ul2f(arg!()));
-    ret!(aeabi_uldivmod(arg!(), arg!()));
-    ret!(moddi3(arg!(), arg!()));
-    ret!(mulodi4(arg!(), arg!()));
-    ret!(powidf2(arg!(), arg!()));
-    ret!(powisf2(arg!(), arg!()));
-    ret!(umoddi3(arg!(), arg!()));
+    bb(aeabi_d2f(bb(2.)));
+    bb(aeabi_d2i(bb(2.)));
+    bb(aeabi_d2l(bb(2.)));
+    bb(aeabi_d2uiz(bb(2.)));
+    bb(aeabi_d2ulz(bb(2.)));
+    bb(aeabi_dadd(bb(2.), bb(3.)));
+    bb(aeabi_dcmpeq(bb(2.), bb(3.)));
+    bb(aeabi_dcmpgt(bb(2.), bb(3.)));
+    bb(aeabi_dcmplt(bb(2.), bb(3.)));
+    bb(aeabi_ddiv(bb(2.), bb(3.)));
+    bb(aeabi_dmul(bb(2.), bb(3.)));
+    bb(aeabi_dsub(bb(2.), bb(3.)));
+    bb(aeabi_f2d(bb(2.)));
+    bb(aeabi_f2iz(bb(2.)));
+    bb(aeabi_f2lz(bb(2.)));
+    bb(aeabi_f2uiz(bb(2.)));
+    bb(aeabi_f2ulz(bb(2.)));
+    bb(aeabi_fadd(bb(2.), bb(3.)));
+    bb(aeabi_fcmpeq(bb(2.), bb(3.)));
+    bb(aeabi_fcmpgt(bb(2.), bb(3.)));
+    bb(aeabi_fcmplt(bb(2.), bb(3.)));
+    bb(aeabi_fdiv(bb(2.), bb(3.)));
+    bb(aeabi_fmul(bb(2.), bb(3.)));
+    bb(aeabi_fsub(bb(2.), bb(3.)));
+    bb(aeabi_i2d(bb(2)));
+    bb(aeabi_i2f(bb(2)));
+    bb(aeabi_idiv(bb(2), bb(3)));
+    bb(aeabi_idivmod(bb(2), bb(3)));
+    bb(aeabi_l2d(bb(2)));
+    bb(aeabi_l2f(bb(2)));
+    bb(aeabi_ldivmod(bb(2), bb(3)));
+    bb(aeabi_lmul(bb(2), bb(3)));
+    bb(aeabi_ui2d(bb(2)));
+    bb(aeabi_ui2f(bb(2)));
+    bb(aeabi_uidiv(bb(2), bb(3)));
+    bb(aeabi_uidivmod(bb(2), bb(3)));
+    bb(aeabi_ul2d(bb(2)));
+    bb(aeabi_ul2f(bb(2)));
+    bb(aeabi_uldivmod(bb(2), bb(3)));
+    bb(moddi3(bb(2), bb(3)));
+    bb(mulodi4(bb(2), bb(3)));
+    bb(powidf2(bb(2.), bb(3)));
+    bb(powisf2(bb(2.), bb(3)));
+    bb(umoddi3(bb(2), bb(3)));
 }
 
 #[cfg(all(feature = "c", not(thumb)))]