From d6bd0a479ceaf6abdd696c3b955a56f66275c562 Mon Sep 17 00:00:00 2001
From: Georgy Yakovlev <gyakovlev@gentoo.org>
Date: Sat, 25 May 2019 22:21:16 -0700
Subject: [PATCH] revert commits triggering multiple llvm rebuilds

this reverts the following commits
https://github.com/rust-lang/rust/commit/105692c3ad281c63bf0f75a26a66bb9cff5b4553
https://github.com/rust-lang/rust/commit/975ba58f42b34ff07cd7c2bd73350daed2057186
https://github.com/rust-lang/rust/commit/e1daa36ba7df88788c2684bbe5ff6eb37f1cda69
---
 src/bootstrap/llvm-rebuild-trigger |  4 +++
 src/bootstrap/native.rs            | 46 +++++++++++++-----------------
 2 files changed, 24 insertions(+), 26 deletions(-)
 create mode 100644 src/bootstrap/llvm-rebuild-trigger

diff --git a/src/bootstrap/llvm-rebuild-trigger b/src/bootstrap/llvm-rebuild-trigger
new file mode 100644
index 0000000000..0f18c6a4ac
--- /dev/null
+++ b/src/rustllvm/llvm-rebuild-trigger
@@ -0,0 +1,4 @@
+# If this file is modified, then llvm will be (optionally) cleaned and then rebuilt.
+# The actual contents of this file do not matter, but to trigger a change on the
+# build bots then the contents should be changed so git updates the mtime.
+2019-03-18
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index fde40b0d1b..3babbc9e10 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -67,40 +67,30 @@ impl Step for Llvm {
             }
         }
 
-        let (llvm_info, root, out_dir, llvm_config_ret_dir) = if emscripten {
-            let info = &builder.emscripten_llvm_info;
+        let rebuild_trigger = builder.src.join("src/rustllvm/llvm-rebuild-trigger");
+        let rebuild_trigger_contents = t!(fs::read_to_string(&rebuild_trigger));
+
+        let (out_dir, llvm_config_ret_dir) = if emscripten {
             let dir = builder.emscripten_llvm_out(target);
             let config_dir = dir.join("bin");
-            (info, "src/llvm-emscripten", dir, config_dir)
+            (dir, config_dir)
         } else {
-            let info = &builder.in_tree_llvm_info;
             let mut dir = builder.llvm_out(builder.config.build);
             if !builder.config.build.contains("msvc") || builder.config.ninja {
                 dir.push("build");
             }
-            (info, "src/llvm-project/llvm", builder.llvm_out(target), dir.join("bin"))
+            (builder.llvm_out(target), dir.join("bin"))
         };
-
-        if !llvm_info.is_git() {
-            println!(
-                "git could not determine the LLVM submodule commit hash. \
-                Assuming that an LLVM build is necessary.",
-            );
-        }
-
+        let done_stamp = out_dir.join("llvm-finished-building");
         let build_llvm_config = llvm_config_ret_dir
             .join(exe("llvm-config", &*builder.config.build));
-        let done_stamp = out_dir.join("llvm-finished-building");
-
-        if let Some(llvm_commit) = llvm_info.sha() {
-            if done_stamp.exists() {
-                let done_contents = t!(fs::read(&done_stamp));
+        if done_stamp.exists() {
+            let done_contents = t!(fs::read_to_string(&done_stamp));
 
-                // If LLVM was already built previously and the submodule's commit didn't change
-                // from the previous build, then no action is required.
-                if done_contents == llvm_commit.as_bytes() {
-                    return build_llvm_config
-                }
+            // If LLVM was already built previously and contents of the rebuild-trigger file
+            // didn't change from the previous build, then no action is required.
+            if done_contents == rebuild_trigger_contents {
+                return build_llvm_config
             }
         }
 
@@ -111,6 +101,7 @@ impl Step for Llvm {
         t!(fs::create_dir_all(&out_dir));
 
         // http://llvm.org/docs/CMake.html
+        let root = if self.emscripten { "src/llvm-emscripten" } else { "src/llvm-project/llvm" };
         let mut cfg = cmake::Config::new(builder.src.join(root));
 
         let profile = match (builder.config.llvm_optimize, builder.config.llvm_release_debuginfo) {
@@ -251,6 +242,11 @@ impl Step for Llvm {
                 channel::CFG_RELEASE_NUM,
                 builder.config.channel,
             );
+            let llvm_info = if self.emscripten {
+                &builder.emscripten_llvm_info
+            } else {
+                &builder.in_tree_llvm_info
+            };
             if let Some(sha) = llvm_info.sha_short() {
                 default_suffix.push_str("-");
                 default_suffix.push_str(sha);
@@ -283,9 +279,7 @@ impl Step for Llvm {
 
         cfg.build();
 
-        if let Some(llvm_commit) = llvm_info.sha() {
-            t!(fs::write(&done_stamp, llvm_commit));
-        }
+        t!(fs::write(&done_stamp, &rebuild_trigger_contents));
 
         build_llvm_config
     }
-- 
2.21.0