Implement basic inline asm support (rust-lang#72)

* Implement basic support for inline assembly

* Disable LTO

We don't support it yet at all

* Handle `inout(reg) var` correctly

Turns out that `+` readwrite output registers cannot be tied with
input variables.

* Add limited support for llvm_asm!

* Handle CHANNEL correctly

* Add support for arbitrary explicit registers

* Handle symbols properly

* Add rudimentary asm tests

* Exclude llvm_asm! tests from tests runs

* Insert `__builtin_unreachable()` after diverging asm blocks

Author: Commeownist

.gitignore

@@ -7,9 +7,11 @@ perf.data.old
 *.events
 *.string*
 /build_sysroot/sysroot
+/build_sysroot/sysroot_src
 /build_sysroot/Cargo.lock
 /build_sysroot/test_target/Cargo.lock
 /rust
+/simple-raytracer
 /regex
 gimple*
 *asm

Cargo.lock

@@ -3,7 +3,12 @@
 #set -x
 set -e
 
-export GCC_PATH=$(cat gcc_path)
+if [ -f ./gcc_path ]; then 
+    export GCC_PATH=$(cat gcc_path)
+else
+    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
+    exit 1
+fi
 
 export LD_LIBRARY_PATH="$GCC_PATH"
 export LIBRARY_PATH="$GCC_PATH"

build.sh

@@ -20,4 +20,4 @@ fi
 cmd=$1
 shift
 
-RUSTDOCFLAGS=$RUSTFLAGS cargo +${TOOLCHAIN} $cmd --target $TARGET_TRIPLE $@
+RUSTDOCFLAGS="$RUSTFLAGS" cargo +${TOOLCHAIN} $cmd --target $TARGET_TRIPLE $@

cargo.sh

@@ -2,7 +2,12 @@ set -e
 
 export CARGO_INCREMENTAL=0
 
-export GCC_PATH=$(cat gcc_path)
+if [ -f ./gcc_path ]; then 
+    export GCC_PATH=$(cat gcc_path)
+else
+    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
+    exit 1
+fi
 
 unamestr=`uname`
 if [[ "$unamestr" == 'Linux' ]]; then
@@ -30,7 +35,7 @@ if [[ "$HOST_TRIPLE" != "$TARGET_TRIPLE" ]]; then
    fi
 fi
 
-export RUSTFLAGS=$linker' -Cpanic=abort -Cdebuginfo=2 -Zpanic-abort-tests -Zcodegen-backend='$(pwd)'/target/'$CHANNEL'/librustc_codegen_gcc.'$dylib_ext' --sysroot '$(pwd)'/build_sysroot/sysroot'
+export RUSTFLAGS="$linker -Cpanic=abort -Cdebuginfo=2 -Clto=off -Zpanic-abort-tests -Zcodegen-backend=$(pwd)/target/${CHANNEL:-debug}/librustc_codegen_gcc.$dylib_ext --sysroot $(pwd)/build_sysroot/sysroot"
 
 # FIXME(antoyo): remove once the atomic shim is gone
 if [[ `uname` == 'Darwin' ]]; then