auto merge of #8855 : michaelwoerister/rust/captured_vars, r=jdm

This pull request includes
* support for variables captured in closures*,
* a fix for issue #8512: arguments of non-immediate type (structs, tuples, etc) passed by value can now be accessed correctly in GDB. (I managed to fix this by using `llvm::DIBuilder::createComplexVariable()`. ~~However, I am not sure if this relies on unstable implementation details of LLVM's debug info handling. I'll try to clarify this on the LLVM mailing list~~).
* simplification of the `debuginfo` module's public interface: the caller of functions like `create_local_var_metadata()` doesn't have to know and catch all cases when it mustn't call the function,
* a cleanup refactoring with unified handling for locals, [self] arguments, captured variables, and match bindings,
* and proper span information for self arguments.

\* However, see comment at https://github.com/michaelwoerister/rust/blob/1d916ace136a27e354d73d65f488603c65f65bd2/src/test/debug-info/var-captured-in-nested-closure.rs#L62 . This is the same problem as with the fix for issue #8512 above: We are probably using `llvm.dbg.declare` in an unsupported way that works today but might not work after the next LLVM update.

Cheers,
Michael

Fixes #8512
Fixes #1341 

1 files changed, 36 insertions, 0 deletions

diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index 54af6fe7e73..376adf24e25 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -724,3 +724,39 @@ extern "C" LLVMValueRef LLVMDIBuilderCreateTemplateTypeParameter(
       LineNo,
       ColumnNo));
 }
+
+extern "C" LLVMValueRef LLVMDIBuilderCreateOpDeref(LLVMTypeRef IntTy)
+{
+    return LLVMConstInt(IntTy, DIBuilder::OpDeref, true);
+}
+
+extern "C" LLVMValueRef LLVMDIBuilderCreateOpPlus(LLVMTypeRef IntTy)
+{
+    return LLVMConstInt(IntTy, DIBuilder::OpPlus, true);
+}
+
+extern "C" LLVMValueRef LLVMDIBuilderCreateComplexVariable(
+    DIBuilderRef Builder,
+    unsigned Tag,
+    LLVMValueRef Scope,
+    const char *Name,
+    LLVMValueRef File,
+    unsigned LineNo,
+    LLVMValueRef Ty,
+    LLVMValueRef* AddrOps,
+    unsigned AddrOpsCount,
+    unsigned ArgNo)
+{
+    llvm::ArrayRef<llvm::Value*> addr_ops((llvm::Value**)AddrOps, AddrOpsCount);
+
+    return wrap(Builder->createComplexVariable(
+        Tag,
+        unwrapDI<DIDescriptor>(Scope),
+        Name,
+        unwrapDI<DIFile>(File),
+        LineNo,
+        unwrapDI<DIType>(Ty),
+        addr_ops,
+        ArgNo
+    ));
+}