Bump the minimum LLVM to 3.9

.travis.yml

@@ -12,7 +12,7 @@ matrix:
   fast_finish: true
   include:
     # Images used in testing PR and try-build should be run first.
-    - env: IMAGE=x86_64-gnu-llvm-3.7 RUST_BACKTRACE=1
+    - env: IMAGE=x86_64-gnu-llvm-3.9 RUST_BACKTRACE=1
       if: type = pull_request OR branch = auto
 
     - env: IMAGE=dist-x86_64-linux DEPLOY=1

config.toml.example

@@ -35,7 +35,7 @@
 # If an external LLVM root is specified, we automatically check the version by
 # default to make sure it's within the range that we're expecting, but setting
 # this flag will indicate that this version check should not be done.
-#version-check = false
+#version-check = true
 
 # Link libstdc++ statically into the librustc_llvm instead of relying on a
 # dynamic version to be available.

src/bootstrap/config.rs

@@ -299,6 +299,7 @@ impl Config {
         let mut config = Config::default();
         config.llvm_enabled = true;
         config.llvm_optimize = true;
+        config.llvm_version_check = true;
         config.use_jemalloc = true;
         config.backtrace = true;
         config.rust_optimize = true;

src/bootstrap/native.rs

@@ -259,11 +259,14 @@ fn check_llvm_version(build: &Build, llvm_config: &Path) {
 
     let mut cmd = Command::new(llvm_config);
     let version = output(cmd.arg("--version"));
-    if version.starts_with("3.5") || version.starts_with("3.6") ||
-       version.starts_with("3.7") {
-        return
+    let mut parts = version.split('.').take(2)
+        .filter_map(|s| s.parse::<u32>().ok());
+    if let (Some(major), Some(minor)) = (parts.next(), parts.next()) {
+        if major > 3 || (major == 3 && minor >= 9) {
+            return
+        }
     }
-    panic!("\n\nbad LLVM version: {}, need >=3.5\n\n", version)
+    panic!("\n\nbad LLVM version: {}, need >=3.9\n\n", version)
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]

src/ci/docker/x86_64-gnu-llvm-3.7/Dockerfile → src/ci/docker/x86_64-gnu-llvm-3.9/Dockerfile

@@ -11,15 +11,17 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   cmake \
   sudo \
   gdb \
-  llvm-3.7-tools \
+  llvm-3.9-tools \
   libedit-dev \
   zlib1g-dev \
   xz-utils
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+# using llvm-link-shared due to libffi issues -- see #34486
 ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
-      --llvm-root=/usr/lib/llvm-3.7
+      --llvm-root=/usr/lib/llvm-3.9 \
+      --enable-llvm-link-shared
 ENV RUST_CHECK_TARGET check

src/test/codegen/abi-x86-interrupt.rs

@@ -14,7 +14,6 @@
 
 // ignore-arm
 // ignore-aarch64
-// min-llvm-version 3.8
 
 // compile-flags: -C no-prepopulate-passes
 

src/test/codegen/mainsubprogram.rs

@@ -8,14 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// The minimum LLVM version is set to 3.8, but really this test
-// depends on a patch that is was committed to upstream LLVM before
-// 4.0; and also backported to the Rust LLVM fork.
+// This test depends on a patch that was committed to upstream LLVM
+// before 4.0, formerly backported to the Rust LLVM fork.
 
 // ignore-tidy-linelength
 // ignore-windows
 // ignore-macos
-// min-llvm-version 3.8
+// min-llvm-version 4.0
 
 // compile-flags: -g -C no-prepopulate-passes
 

src/test/codegen/mainsubprogramstart.rs

@@ -8,14 +8,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// The minimum LLVM version is set to 3.8, but really this test
-// depends on a patch that is was committed to upstream LLVM before
-// 4.0; and also backported to the Rust LLVM fork.
+// This test depends on a patch that was committed to upstream LLVM
+// before 4.0, formerly backported to the Rust LLVM fork.
 
 // ignore-tidy-linelength
 // ignore-windows
 // ignore-macos
-// min-llvm-version 3.8
+// min-llvm-version 4.0
 
 // compile-flags: -g -C no-prepopulate-passes
 

src/test/run-pass/issue-36023.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// min-llvm-version 3.9
-
 use std::ops::Deref;
 
 fn main() {