Auto merge of #99464 - nikic:llvm-15, r=cuviper

Update to LLVM 15

For preliminary testing. Some LLVM 15 compatibility fixes were applied separately in #99512.

Release timeline:
 * LLVM 15 branched on Jul 26.
 * The final LLVM 15.0.0 release is scheduled for Sep 6.
 * Current nightly (1.65.0) is scheduled for Nov 3.

Changes in this PR (apart from the LLVM update):
 * Pass `--set llvm.allow-old-toolchain` for many Docker images. LLVM 16 will require GCC >= 7.1, while LLVM 15 still allows older compilers with an option. Specify the option for builders still using GCC 5.4. #95026 updated some of the used toolchains, but not all.
 * Use the `+atomics-32` target feature for thumbv6m.
 * Explicitly link libatomic when cross-compiling LLVM to 32-bit target.
 * Explicitly disable zstd support, to avoid libzstd.so dependency.

New LLVM patches ([commits](https://github.com/rust-lang/llvm-project/commits/rustc/15.0-2022-08-09)):
 * [rust-only] Fix ICE with GCC 5.4 (https://github.com/nikic/llvm-project/commit/15be58d7f0342b1da5af219bac8bd71d01da6dff)
 * [rust-only] Fix build with GCC 5.4 (https://github.com/nikic/llvm-project/commit/774edc10fa45229c2aa678f1bef8b4812dc0f76a)
 * ~~[rust-only] Fix build with GCC 5.2 (https://github.com/nikic/llvm-project/commit/1a6069a7bb35ace1e40d566035cbf7ed2fa3b1f7)~~
 * ~~[rust-only] Fix ICE with GCC 5.2 (https://github.com/nikic/llvm-project/commit/493081f2909206e0ed55af68a4058a76c0ad7a64)~~
 * ~~[rust-only] Fix build with GCC 5.2 (https://github.com/nikic/llvm-project/commit/0fc5979d738c3a1f9510fe2d62417f7d2af37817)~~
 * [backported] Addition of `+atomics` target feature (https://github.com/llvm/llvm-project/commit/57bdd9892d0eba5bdd25fc44799235be7b9f5153).
 * [backported] Revert compiler-rt change that broke powerpc (https://github.com/llvm/llvm-project/commit/9c68b43915fc1c9c0a07e935163ae8d638d7241b)
 * [awaiting backport] Fix RelLookupTableConverter on gnux32 (https://github.com/nikic/llvm-project/commit/639388a05f25772fb23eea5b1045e7df83bcfaa7 / https://github.com/llvm/llvm-project/issues/57021)

Tested images: dist-x86_64-linux, armhf-gnu, arm-android, dist-s390x-linux, dist-x86_64-illumos, dist-x86_64-freebsd, wasm32, dist-x86_64-musl, dist-various-1, dist-riscv64-linux, dist-mips-linux, dist-mipsel-linux, dist-powerpc-linux, dist-aarch64-linux, dist-x86_64-apple, x86_64-msvc-1, x86_64-msvc-2, dist-various-2, dist-arm-linux
Tested up to the usual ipv6 error: test-various, i686-gnu, x86_64-gnu-nopt

r? `@ghost`

13 files changed, 25 insertions, 12 deletions

diff --git a/src/ci/docker/host-x86_64/arm-android/Dockerfile b/src/ci/docker/host-x86_64/arm-android/Dockerfile
index 43cdbbe92e3..a2335687ab3 100644
--- a/src/ci/docker/host-x86_64/arm-android/Dockerfile
+++ b/src/ci/docker/host-x86_64/arm-android/Dockerfile
@@ -29,7 +29,8 @@ ENV PATH=$PATH:/android/sdk/platform-tools
 
 ENV TARGETS=arm-linux-androideabi
 
-ENV RUST_CONFIGURE_ARGS --arm-linux-androideabi-ndk=/android/ndk/arm-14
+ENV RUST_CONFIGURE_ARGS --arm-linux-androideabi-ndk=/android/ndk/arm-14 \
+    --set llvm.allow-old-toolchain
 
 ENV SCRIPT python3 ../x.py --stage 2 test --host='' --target $TARGETS
 
diff --git a/src/ci/docker/host-x86_64/dist-android/Dockerfile b/src/ci/docker/host-x86_64/dist-android/Dockerfile
index 2f0496d7dd4..c98fa496d48 100644
--- a/src/ci/docker/host-x86_64/dist-android/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-android/Dockerfile
@@ -32,7 +32,8 @@ ENV RUST_CONFIGURE_ARGS \
       --i686-linux-android-ndk=/android/ndk/x86-14 \
       --aarch64-linux-android-ndk=/android/ndk/arm64-21 \
       --x86_64-linux-android-ndk=/android/ndk/x86_64-21 \
-      --disable-docs
+      --disable-docs \
+      --set llvm.allow-old-toolchain
 
 ENV SCRIPT python3 ../x.py dist --host='' --target $TARGETS
 
diff --git a/src/ci/docker/host-x86_64/dist-i586-gnu-i586-i686-musl/Dockerfile b/src/ci/docker/host-x86_64/dist-i586-gnu-i586-i686-musl/Dockerfile
index c98fc7dcfff..b0d65428ec6 100644
--- a/src/ci/docker/host-x86_64/dist-i586-gnu-i586-i686-musl/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-i586-gnu-i586-i686-musl/Dockerfile
@@ -36,7 +36,8 @@ RUN /scripts/cmake.sh
 ENV RUST_CONFIGURE_ARGS \
       --musl-root-i586=/musl-i586 \
       --musl-root-i686=/musl-i686 \
-      --disable-docs
+      --disable-docs \
+      --set llvm.allow-old-toolchain
 
 # Newer binutils broke things on some vms/distros (i.e., linking against
 # unknown relocs disabled by the following flag), so we need to go out of our
diff --git a/src/ci/docker/host-x86_64/dist-mips-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-mips-linux/Dockerfile
index b0f06569a9c..948fa40dd4b 100644
--- a/src/ci/docker/host-x86_64/dist-mips-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-mips-linux/Dockerfile
@@ -26,5 +26,6 @@ RUN /scripts/cmake.sh
 
 ENV HOSTS=mips-unknown-linux-gnu
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/dist-mips64-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-mips64-linux/Dockerfile
index 245c28e1fa3..fd15dbd22c6 100644
--- a/src/ci/docker/host-x86_64/dist-mips64-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-mips64-linux/Dockerfile
@@ -25,5 +25,6 @@ RUN /scripts/cmake.sh
 
 ENV HOSTS=mips64-unknown-linux-gnuabi64
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/dist-mips64el-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-mips64el-linux/Dockerfile
index 03998c8880a..376bdfb4a2f 100644
--- a/src/ci/docker/host-x86_64/dist-mips64el-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-mips64el-linux/Dockerfile
@@ -26,5 +26,6 @@ RUN /scripts/cmake.sh
 
 ENV HOSTS=mips64el-unknown-linux-gnuabi64
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/dist-mipsel-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-mipsel-linux/Dockerfile
index 58617270621..70c8b2a96c8 100644
--- a/src/ci/docker/host-x86_64/dist-mipsel-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-mipsel-linux/Dockerfile
@@ -25,5 +25,6 @@ RUN /scripts/cmake.sh
 
 ENV HOSTS=mipsel-unknown-linux-gnu
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/dist-x86_64-netbsd/Dockerfile b/src/ci/docker/host-x86_64/dist-x86_64-netbsd/Dockerfile
index 92bdc9811fd..fed4be4c30a 100644
--- a/src/ci/docker/host-x86_64/dist-x86_64-netbsd/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-x86_64-netbsd/Dockerfile
@@ -21,5 +21,6 @@ ENV \
 
 ENV HOSTS=x86_64-unknown-netbsd
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile b/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
index 0182ebb8b59..1f8d0a64ea4 100644
--- a/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
+++ b/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
@@ -27,6 +27,7 @@ RUN mkdir -p /config
 RUN echo "[rust]" > /config/nopt-std-config.toml
 RUN echo "optimize = false" >> /config/nopt-std-config.toml
 
-ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests
+ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py test --stage 0 --config /config/nopt-std-config.toml library/std \
   && python3 ../x.py --stage 2 test
diff --git a/src/ci/docker/host-x86_64/i686-gnu/Dockerfile b/src/ci/docker/host-x86_64/i686-gnu/Dockerfile
index feaab819bdd..7bca0398dea 100644
--- a/src/ci/docker/host-x86_64/i686-gnu/Dockerfile
+++ b/src/ci/docker/host-x86_64/i686-gnu/Dockerfile
@@ -23,7 +23,8 @@ RUN sh /scripts/sccache.sh
 COPY scripts/cmake.sh /scripts/
 RUN /scripts/cmake.sh
 
-ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu
+ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu \
+    --set llvm.allow-old-toolchain
 # Exclude some tests that are unlikely to be platform specific, to speed up
 # this slow job.
 ENV SCRIPT python3 ../x.py --stage 2 test \
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile
index ee3cd092f4c..bfc6975c19d 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-aux/Dockerfile
@@ -26,5 +26,6 @@ RUN sh /scripts/sccache.sh
 COPY scripts/cmake.sh /scripts/
 RUN /scripts/cmake.sh
 
-ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu
+ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu \
+    --set llvm.allow-old-toolchain
 ENV RUST_CHECK_TARGET check-aux
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile
index 09d9cda02bd..4bb4042cd7e 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-distcheck/Dockerfile
@@ -22,6 +22,7 @@ RUN sh /scripts/sccache.sh
 COPY scripts/cmake.sh /scripts/
 RUN /scripts/cmake.sh
 
-ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu --set rust.ignore-git=false
+ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu --set rust.ignore-git=false \
+    --set llvm.allow-old-toolchain
 ENV SCRIPT python3 ../x.py --stage 2 test distcheck
 ENV DIST_SRC 1
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index 2358091a6df..f442a477a7b 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -81,6 +81,7 @@ COPY host-x86_64/x86_64-gnu-tools/browser-ui-test.version /tmp/
 RUN npm install -g browser-ui-test@$(head -n 1 /tmp/browser-ui-test.version) --unsafe-perm=true
 
 ENV RUST_CONFIGURE_ARGS \
+  --set llvm.allow-old-toolchain \
   --build=x86_64-unknown-linux-gnu \
   --save-toolstates=/tmp/toolstate/toolstates.json