firmware: use compiler_builtins crate instead of our compiler-rt.

This cannot be done for ksupport yet because compiler_builtins
misses most soft-float operations.

artiq/firmware/Cargo.lock

@@ -29,6 +29,15 @@ name = "byteorder"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "compiler_builtins"
+version = "0.1.0"
+source = "git+https://github.com/rust-lang-nursery/compiler-builtins#631b5687b24af413fdbffa4c2644484e60660b00"
+dependencies = [
+ "gcc 0.3.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-cfg 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "cslice"
 version = "0.3.0"
@@ -42,6 +51,11 @@ dependencies = [
  "libc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "gcc"
+version = "0.3.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "kernel32-sys"
 version = "0.2.2"
@@ -100,6 +114,7 @@ dependencies = [
  "board 0.0.0",
  "build_artiq 0.0.0",
  "byteorder 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.1.0 (git+https://github.com/rust-lang-nursery/compiler-builtins)",
  "fringe 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "logger_artiq 0.0.0",
@@ -107,6 +122,11 @@ dependencies = [
  "std_artiq 0.0.0",
 ]
 
+[[package]]
+name = "rustc-cfg"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "satman"
 version = "0.0.0"
@@ -150,13 +170,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [metadata]
 "checksum byteorder 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c40977b0ee6b9885c9013cd41d9feffdd22deb3bb4dc3a71d901cc7a77de18c8"
+"checksum compiler_builtins 0.1.0 (git+https://github.com/rust-lang-nursery/compiler-builtins)" = "<none>"
 "checksum cslice 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0f8cb7306107e4b10e64994de6d3274bd08996a7c1322a27b86482392f96be0a"
 "checksum fringe 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "987689dcfad85eee8d76b477865641ec483e63fb86d52966bfc350c4a647d78a"
+"checksum gcc 0.3.42 (registry+https://github.com/rust-lang/crates.io-index)" = "291055c78f59ca3d84c99026c9501c469413d386bb46be1e1cf1d285cd1db3b0"
 "checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
 "checksum libc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "a51822fc847e7a8101514d1d44e354ba2ffa7d4c194dcab48870740e327cac70"
 "checksum log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "ab83497bf8bf4ed2a74259c1c802351fcd67a65baa86394b6ba73c36f4838054"
 "checksum log_buffer 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ec57723b84bbe7bdf76aa93169c9b59e67473317c6de3a83cb2a0f8ccb2aa493"
 "checksum managed 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "5981b4c6de5ce272aaf2caaa56adb8f6fd24a73206b38302db572ab9374aab10"
+"checksum rustc-cfg 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "56a596b5718bf5e059d59a30af12f7f462a152de147aa462b70892849ee18704"
 "checksum smoltcp 0.2.1 (git+https://github.com/m-labs/smoltcp?rev=e8ece3e)" = "<none>"
 "checksum walkdir 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "dd7c16466ecc507c7cb5988db03e6eab4aaeab89a5c37a29251fcfd3ac9b7afe"
 "checksum winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"

artiq/firmware/runtime/Cargo.toml

@@ -13,6 +13,7 @@ path = "lib.rs"
 build_artiq = { path = "../libbuild_artiq" }
 
 [dependencies]
+compiler_builtins = { git = "https://github.com/rust-lang-nursery/compiler-builtins" }
 alloc_artiq = { path = "../liballoc_artiq" }
 std_artiq = { path = "../libstd_artiq", features = ["alloc"] }
 logger_artiq = { path = "../liblogger_artiq" }

artiq/firmware/runtime/lib.rs

@@ -1,6 +1,7 @@
 #![no_std]
-#![feature(libc, repr_simd, const_fn)]
+#![feature(compiler_builtins_lib, libc, repr_simd, const_fn)]
 
+extern crate compiler_builtins;
 extern crate alloc_artiq;
 #[macro_use]
 extern crate std_artiq as std;

artiq/runtime/Makefile

@@ -43,7 +43,7 @@ runtime.elf: $(RUSTOUT)/libruntime.a ksupport_data.o
 		-T $(RUNTIME_DIRECTORY)/runtime.ld \
 		-o $@ \
 		$^ \
-		-lbase-nofloat -lcompiler-rt
+		-lbase-nofloat
 	@chmod -x $@
 
 .PHONY: $(RUSTOUT_KSUPPORT)/libksupport.a