Fix __divsi3 and __udivsi3 on thumbv6m targets

This commit fixes a bug accidentally introduced in rust-lang#285 where some
lingering references remained to `#[cfg(thumbv6m)]` but this, since the
historical revert, was renamed to `#[cfg(thumb_1)]`. This caused on the
thumbv6m platform for the intrinsics to be accidentally omitted because
the build script didn't actually compile them but the Rust code thought
the C code was in use.

After correcting the `#[cfg]` statements the CI configuration for the
`thumb*` family of targets was all updated. The support for xargo
testing was removed from `run.sh` since it had long since bitrotted, and
the script was updated to simply build the intrinsics example to attempt
to link for each of these targets. This in turn exposed the bug locally
and allowed to confirm a fix once the `#[cfg]` statements were
corrected.

cc rust-lang/rust#60782

Author: alexcrichton

Cargo.toml

@@ -62,7 +62,7 @@ rustc-dep-of-std = ['c', 'compiler-builtins', 'core']
 
 [[example]]
 name = "intrinsics"
-required-features = ["c", "compiler-builtins"]
+required-features = ["compiler-builtins"]
 
 [workspace]
 members = ["testcrate"]

azure-pipelines.yml

@@ -33,18 +33,14 @@ jobs:
           TARGET: powerpc64-unknown-linux-gnu
         powerpc64le:
           TARGET: powerpc64le-unknown-linux-gnu
-        # thumbv6m:
-        #   TARGET: thumbv6m-linux-eabi
-        #   XARGO: 1
-        # thumbv7em:
-        #   TARGET: thumbv7em-linux-eabi
-        #   XARGO: 1
-        # thumbv7emhf:
-        #   TARGET: thumbv7em-linux-eabihf
-        #   XARGO: 1
-        # thumbv7m:
-        #   TARGET: thumbv7m-linux-eabi
-        #   XARGO: 1
+        thumbv6m:
+          TARGET: thumbv6m-none-eabi
+        thumbv7em:
+          TARGET: thumbv7em-none-eabi
+        thumbv7emhf:
+          TARGET: thumbv7em-none-eabihf
+        thumbv7m:
+          TARGET: thumbv7m-none-eabi
         wasm32:
           TARGET: wasm32-unknown-unknown
           ONLY_BUILD: 1

ci/docker/thumbv6m-linux-eabi/Dockerfile

@@ -0,0 +1,7 @@
+FROM ubuntu:18.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    gcc libc6-dev ca-certificates \
+    gcc-arm-none-eabi \
+    libnewlib-arm-none-eabi
+ENV XARGO=1

ci/docker/thumbv6m-none-eabi/Dockerfile

@@ -0,0 +1,7 @@
+FROM ubuntu:18.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    gcc libc6-dev ca-certificates \
+    gcc-arm-none-eabi \
+    libnewlib-arm-none-eabi
+ENV XARGO=1

ci/docker/thumbv7em-linux-eabi/Dockerfile

@@ -0,0 +1,7 @@
+FROM ubuntu:18.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    gcc libc6-dev ca-certificates \
+    gcc-arm-none-eabi \
+    libnewlib-arm-none-eabi
+ENV XARGO=1

ci/docker/thumbv7em-linux-eabihf/Dockerfile

@@ -0,0 +1,7 @@
+FROM ubuntu:18.04
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    gcc libc6-dev ca-certificates \
+    gcc-arm-none-eabi \
+    libnewlib-arm-none-eabi
+ENV XARGO=1

ci/docker/thumbv7em-none-eabi/Dockerfile

@@ -18,7 +18,6 @@ run() {
            --user $(id -u):$(id -g) \
            -e CARGO_HOME=/cargo \
            -e CARGO_TARGET_DIR=/target \
-           -e XARGO \
            -v $HOME/.cargo:/cargo \
            -v `pwd`/target:/target \
            -v `pwd`:/checkout:ro \

ci/docker/thumbv7em-none-eabihf/Dockerfile

@@ -1,53 +1,24 @@
 set -ex
 
-# FIXME(japarix/xargo#186) this shouldn't be necessary
-export RUST_TARGET_PATH=`pwd`
-
 cargo=cargo
-if [ "$XARGO" = "1" ]; then
-  cargo=xargo
-fi
-
-INTRINSICS_FEATURES="c"
-
-# Some architectures like ARM apparently seem to require the `mem` feature
-# enabled to successfully compile the `intrinsics` example, and... we're not
-# sure why!
-if [ -z "$INTRINSICS_FAILS_WITH_MEM_FEATURE" ]; then
-  INTRINSICS_FEATURES="$INTRINSICS_FEATURES mem"
-fi
 
 # Test our implementation
 if [ "$XARGO" = "1" ]; then
-    run="xargo test --manifest-path testcrate/Cargo.toml --target $1"
-    for t in $(ls testcrate/tests); do
-        t=${t%.rs}
-
-        RUSTFLAGS="-C debug-assertions=no -C lto" \
-        CARGO_INCREMENTAL=0 \
-          $run --test $t --no-default-features --features 'mem c' --no-run
-        qemu-arm-static target/${1}/debug/$t-*
-    done
-
-    for t in $(ls testcrate/tests); do
-        t=${t%.rs}
-        RUSTFLAGS="-C lto" \
-        CARGO_INCREMENTAL=0 \
-          $run --test $t --no-default-features --features 'mem c' --no-run --release
-        qemu-arm-static target/${1}/release/$t-*
-    done
+    # FIXME: currently these tests don't work...
+    echo nothing to do
 else
     run="cargo test --manifest-path testcrate/Cargo.toml --target $1"
     $run
     $run --release
     $run --features c
     $run --features c --release
-    cargo build --target $1
-    cargo build --target $1 --release
-    cargo build --target $1 --features c
-    cargo build --target $1 --release --features c
 fi
 
+cargo build --target $1
+cargo build --target $1 --release
+cargo build --target $1 --features c
+cargo build --target $1 --release --features c
+
 PREFIX=$(echo $1 | sed -e 's/unknown-//')-
 case $1 in
     armv7-*)
@@ -101,8 +72,11 @@ done
 rm -f $path
 
 # Verify that we haven't drop any intrinsic/symbol
-RUSTFLAGS="-C debug-assertions=no" \
-  $cargo build --features "$INTRINSICS_FEATURES" --target $1 --example intrinsics -v
+build_intrinsics="$cargo build --target $1 -v --example intrinsics"
+RUSTFLAGS="-C debug-assertions=no" $build_intrinsics
+RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --release
+RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --features c
+RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --features c --release
 
 # Verify that there are no undefined symbols to `panic` within our
 # implementations

ci/docker/thumbv7m-linux-eabi/Dockerfile

@@ -27,7 +27,14 @@ extern {}
 mod intrinsics {
     // trunccdfsf2
     pub fn aeabi_d2f(x: f64) -> f32 {
-        x as f32
+        // This is only implemented in C currently, so only test it there.
+        #[cfg(feature = "c")]
+        return x as f32;
+        #[cfg(not(feature = "c"))]
+        {
+            drop(x);
+            0.0
+        }
     }
 
     // fixdfsi
@@ -263,6 +270,10 @@ mod intrinsics {
     pub fn modti3(a: i128, b: i128) -> i128 {
         a % b
     }
+
+    pub fn udivsi3(a: u32, b: u32) -> u32 {
+        a / b
+    }
 }
 
 fn run() {
@@ -325,6 +336,7 @@ fn run() {
     bb(umodti3(bb(2), bb(2)));
     bb(divti3(bb(2), bb(2)));
     bb(modti3(bb(2), bb(2)));
+    bb(udivsi3(bb(2), bb(2)));
 
     something_with_a_dtor(&|| assert_eq!(bb(1), 1));
 

ci/docker/thumbv7m-none-eabi/Dockerfile

@@ -57,7 +57,7 @@ impl Divmod for i32 {}
 impl Divmod for i64 {}
 
 intrinsics! {
-    #[use_c_shim_if(all(target_arch = "arm", not(target_os = "ios"), not(thumbv6m)))]
+    #[use_c_shim_if(all(target_arch = "arm", not(target_os = "ios"), not(thumb_1)))]
     #[arm_aeabi_alias = __aeabi_idiv]
     pub extern "C" fn __divsi3(a: i32, b: i32) -> i32 {
         a.div(b)

ci/run-docker.sh

@@ -154,7 +154,7 @@ macro_rules! udivmod_inner {
 intrinsics! {
     #[use_c_shim_if(all(target_arch = "arm",
                         not(target_os = "ios"),
-                        not(thumbv6m)))]
+                        not(thumb_1)))]
     #[arm_aeabi_alias = __aeabi_uidiv]
     /// Returns `n / d`
     pub extern "C" fn __udivsi3(n: u32, d: u32) -> u32 {