Compiler specs: dispose LLVM JIT as soon as possible.

This seems to fix an issue with unwind stopping to work well after using a JIT without disposing it. See #3439
crystal-lang · Oct 21, 2016 · 7517056 · 7517056
1 parent 13b11d7
commit 7517056
Showing 2 changed files with 27 additions and 2 deletions.
diff --git a/src/compiler/crystal/codegen/codegen.cr b/src/compiler/crystal/codegen/codegen.cr
@@ -45,8 +45,19 @@ module Crystal
 
       llvm_mod.verify
 
-      engine = LLVM::JITCompiler.new(llvm_mod)
-      engine.run_function wrapper, [] of LLVM::GenericValue
+      # We use the block form so we dispose the JIT as soon as possible.
+      # This isn't really needed, but on LLVM 3.9 it sometimes messes the
+      # stack trace for unwind, or so it seems, or there's something else
+      # that for now we can't understand.
+      #
+      # Since this only affects specs (not the code that is generated by
+      # the compiler) we can postpone the understanding and continue
+      # running specs just fine.
+      #
+      # See https://github.com/crystal-lang/crystal/pull/3439
+      LLVM::JITCompiler.new(llvm_mod) do |jit|
+        jit.run_function wrapper, [] of LLVM::GenericValue
+      end
     end
 
     def codegen(node, single_module = false, debug = false, llvm_mod = LLVM::Module.new("main_module"), expose_crystal_main = true)

diff --git a/src/llvm/jit_compiler.cr b/src/llvm/jit_compiler.cr
@@ -8,6 +8,13 @@ class LLVM::JITCompiler
     if LibLLVM.create_mc_jit_compiler_for_module(out @unwrap, mod, nil, 0, out error) != 0
       raise LLVM.string_and_dispose(error)
     end
+
+    @finalized = false
+  end
+
+  def self.new(mod)
+    jit = new(mod)
+    yield jit ensure jit.dispose
   end
 
   def run_function(func)
@@ -28,7 +35,14 @@ class LLVM::JITCompiler
     @unwrap
   end
 
+  def dispose
+    return if @finalized
+    @finalized = true
+    finalize
+  end
+
   def finalize
+    return if @finalized
     LibLLVM.dispose_execution_engine(@unwrap)
   end
 end