Auto merge of #65251 - tlively:emscripten-upstream-upgrade, r=tlively

Upgrade Emscripten targets to use upstream LLVM backend

 - Compatible with Emscripten 1.38.46-upstream or later upstream.
 - Refactors the Emscripten target spec to share code with other wasm
   targets.
 - Replaces the old incorrect wasm32 C call ABI with the correct one,
   preserving the old one as wasm32_bindgen_compat for wasm-bindgen
   compatibility.
 - Updates the varargs ABI used by Emscripten and deletes the old one.
 - Removes the obsolete wasm32-experimental-emscripten target.
 - Uses EMCC_CFLAGS on CI to avoid the timeout problems with #63649.

r? @alexcrichton

Author: bors

config.toml.example

@@ -377,6 +377,7 @@
 # but you can also optionally enable the "emscripten" backend for asm.js or
 # make this an empty array (but that probably won't get too far in the
 # bootstrap)
+# FIXME: remove the obsolete emscripten backend option.
 #codegen-backends = ["llvm"]
 
 # This is the name of the directory in which codegen backends will get installed

src/bootstrap/builder.rs

@@ -980,6 +980,7 @@ impl<'a> Builder<'a> {
                 Some("-Wl,-rpath,@loader_path/../lib")
             } else if !target.contains("windows") &&
                       !target.contains("wasm32") &&
+                      !target.contains("emscripten") &&
                       !target.contains("fuchsia") {
                 Some("-Wl,-rpath,$ORIGIN/../lib")
             } else {

src/bootstrap/test.rs

@@ -1047,10 +1047,11 @@ impl Step for Compiletest {
         // Also provide `rust_test_helpers` for the host.
         builder.ensure(native::TestHelpers { target: compiler.host });
 
-        // wasm32 can't build the test helpers
-        if !target.contains("wasm32") {
+        // As well as the target, except for plain wasm32, which can't build it
+        if !target.contains("wasm32") || target.contains("emscripten") {
             builder.ensure(native::TestHelpers { target });
         }
+
         builder.ensure(RemoteCopyLibs { compiler, target });
 
         let mut cmd = builder.tool_cmd(Tool::Compiletest);

src/ci/azure-pipelines/auto.yml

@@ -124,14 +124,14 @@ jobs:
         IMAGE: dist-x86_64-netbsd
         DEPLOY: 1
 
-      asmjs:
-        IMAGE: asmjs
       i686-gnu:
         IMAGE: i686-gnu
       i686-gnu-nopt:
         IMAGE: i686-gnu-nopt
       test-various:
         IMAGE: test-various
+      wasm32:
+        IMAGE: wasm32
       x86_64-gnu:
         IMAGE: x86_64-gnu
       x86_64-gnu-full-bootstrap:

src/ci/docker/asmjs/Dockerfile

@@ -0,0 +1,41 @@
+FROM ubuntu:16.04
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  g++ \
+  make \
+  file \
+  curl \
+  ca-certificates \
+  python \
+  git \
+  cmake \
+  sudo \
+  gdb \
+  xz-utils \
+  bzip2
+
+COPY scripts/emscripten.sh /scripts/
+RUN bash /scripts/emscripten.sh
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
+ENV PATH=$PATH:/emsdk-portable
+ENV PATH=$PATH:/emsdk-portable/upstream/emscripten/
+ENV PATH=$PATH:/emsdk-portable/node/12.9.1_64bit/bin/
+ENV BINARYEN_ROOT=/emsdk-portable/upstream/
+
+ENV TARGETS=asmjs-unknown-emscripten
+
+# Use -O1 optimizations in the link step to reduce time spent optimizing JS.
+ENV EMCC_CFLAGS=-O1
+
+# Emscripten installation is user-specific
+ENV NO_CHANGE_USER=1
+
+ENV SCRIPT python2.7 ../x.py test --target $TARGETS
+
+# This is almost identical to the wasm32-unknown-emscripten target, so
+# running with assertions again is not useful
+ENV NO_DEBUG_ASSERTIONS=1
+ENV NO_LLVM_ASSERTIONS=1