Rollup merge of #30452 - dotdash:24876_take_2, r=alexcrichton

LLVM doesn't really support reusing the same module to emit more than
one file. One bug this causes is that the IR is invalidated by the stack
coloring pass when emitting the first file, and then the IR verifier
complains by the time we try to emit the second file. Also, we get
different binaries with --emit=asm,link than with just --emit=link. In
some cases leading to segfaults.

Unfortunately, it seems that at this point in time, the most sensible
option to circumvent this problem is to just clone the whole llvm module
for the asm output if we need both, asm and obj file output.

Fixes #24876
Fixes #26235

5 files changed, 103 insertions, 0 deletions

diff --git a/src/librustc_llvm/lib.rs b/src/librustc_llvm/lib.rs
index 0f05db86742..8dcaa4b5064 100644
--- a/src/librustc_llvm/lib.rs
+++ b/src/librustc_llvm/lib.rs
@@ -616,6 +616,7 @@ extern {
                                              C: ContextRef)
                                              -> ModuleRef;
     pub fn LLVMGetModuleContext(M: ModuleRef) -> ContextRef;
+    pub fn LLVMCloneModule(M: ModuleRef) -> ModuleRef;
     pub fn LLVMDisposeModule(M: ModuleRef);
 
     /// Data layout. See Module::getDataLayout.
diff --git a/src/librustc_trans/back/write.rs b/src/librustc_trans/back/write.rs
index dc20b99f9a6..67eff1ca19f 100644
--- a/src/librustc_trans/back/write.rs
+++ b/src/librustc_trans/back/write.rs
@@ -544,10 +544,22 @@ unsafe fn optimize_and_codegen(cgcx: &CodegenContext,
 
         if config.emit_asm {
             let path = output_names.with_extension(&format!("{}.s", name_extra));
+
+            // We can't use the same module for asm and binary output, because that triggers
+            // various errors like invalid IR or broken binaries, so we might have to clone the
+            // module to produce the asm output
+            let llmod = if config.emit_obj {
+                llvm::LLVMCloneModule(llmod)
+            } else {
+                llmod
+            };
             with_codegen(tm, llmod, config.no_builtins, |cpm| {
                 write_output_file(cgcx.handler, tm, cpm, llmod, &path,
                                   llvm::AssemblyFileType);
             });
+            if config.emit_obj {
+                llvm::LLVMDisposeModule(llmod);
+            }
         }
 
         if config.emit_obj {
diff --git a/src/test/run-make/emit/Makefile b/src/test/run-make/emit/Makefile
new file mode 100644
index 00000000000..be34028fe1d
--- /dev/null
+++ b/src/test/run-make/emit/Makefile
@@ -0,0 +1,15 @@
+-include ../tools.mk
+
+all:
+	$(RUSTC) -Copt-level=0 --emit=llvm-bc,llvm-ir,asm,obj,link test-24876.rs
+	$(RUSTC) -Copt-level=1 --emit=llvm-bc,llvm-ir,asm,obj,link test-24876.rs
+	$(RUSTC) -Copt-level=2 --emit=llvm-bc,llvm-ir,asm,obj,link test-24876.rs
+	$(RUSTC) -Copt-level=3 --emit=llvm-bc,llvm-ir,asm,obj,link test-24876.rs
+	$(RUSTC) -Copt-level=0 --emit=llvm-bc,llvm-ir,asm,obj,link test-26235.rs
+	$(call RUN,test-26235) || exit 1
+	$(RUSTC) -Copt-level=1 --emit=llvm-bc,llvm-ir,asm,obj,link test-26235.rs
+	$(call RUN,test-26235) || exit 1
+	$(RUSTC) -Copt-level=2 --emit=llvm-bc,llvm-ir,asm,obj,link test-26235.rs
+	$(call RUN,test-26235) || exit 1
+	$(RUSTC) -Copt-level=3 --emit=llvm-bc,llvm-ir,asm,obj,link test-26235.rs
+	$(call RUN,test-26235) || exit 1
diff --git a/src/test/run-make/emit/test-24876.rs b/src/test/run-make/emit/test-24876.rs
new file mode 100644
index 00000000000..ab69decbf00
--- /dev/null
+++ b/src/test/run-make/emit/test-24876.rs
@@ -0,0 +1,19 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Checks for issue #24876
+
+fn main() {
+    let mut v = 0;
+    for i in 0..0 {
+        v += i;
+    }
+    println!("{}", v)
+}
diff --git a/src/test/run-make/emit/test-26235.rs b/src/test/run-make/emit/test-26235.rs
new file mode 100644
index 00000000000..97b58a3671b
--- /dev/null
+++ b/src/test/run-make/emit/test-26235.rs
@@ -0,0 +1,56 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Checks for issue #26235
+
+fn main() {
+    use std::thread;
+
+    type Key = u32;
+    const NUM_THREADS: usize = 2;
+
+    #[derive(Clone,Copy)]
+    struct Stats<S> {
+        upsert: S,
+        delete: S,
+        insert: S,
+        update: S
+    };
+
+    impl<S> Stats<S> where S: Copy {
+        fn dot<B, F, T>(self, s: Stats<T>, f: F) -> Stats<B> where F: Fn(S, T) -> B {
+            let Stats { upsert: u1, delete: d1, insert: i1, update: p1 } = self;
+            let Stats { upsert: u2, delete: d2, insert: i2, update: p2 } = s;
+            Stats { upsert: f(u1, u2), delete: f(d1, d2), insert: f(i1, i2), update: f(p1, p2) }
+        }
+
+        fn new(init: S) -> Self {
+            Stats { upsert: init, delete: init, insert: init, update: init }
+        }
+    }
+
+    fn make_threads() -> Vec<thread::JoinHandle<()>> {
+        let mut t = Vec::with_capacity(NUM_THREADS);
+        for _ in 0..NUM_THREADS {
+            t.push(thread::spawn(move || {}));
+        }
+        t
+    }
+
+    let stats = [Stats::new(0); NUM_THREADS];
+    make_threads();
+
+    {
+        let Stats { ref upsert, ref delete, ref insert, ref update } = stats.iter().fold(
+            Stats::new(0), |res, &s| res.dot(s, |x: Key, y: Key| x.wrapping_add(y)));
+        println!("upserts: {}, deletes: {}, inserts: {}, updates: {}",
+                 upsert, delete, insert, update);
+    }
+}