Fix nested functions.

My last patch was a little over-zealous in passing `undef`, it always passed
`undef` to inner functions expecting a single context frame.

gen/nested.cpp

@@ -5,6 +5,7 @@
 #include "gen/llvmhelpers.h"
 #include "gen/logger.h"
 #include "gen/tollvm.h"
+#include "gen/functions.h"
 
 #include "llvm/Support/CommandLine.h"
 namespace cl = llvm::cl;
@@ -237,16 +238,19 @@ LLValue* DtoNestedContext(Loc loc, Dsymbol* sym)
         return llvm::UndefValue::get(getVoidPtrType());
     }
     if (nestedCtx == NCHybrid) {
-        // If sym is a nested function, and it's parent context is different than the
-        // one we got, adjust it.
+        if (FuncDeclaration* symfd = sym->isFuncDeclaration()) {
+            // Make sure we've had a chance to analyze nested context usage
+            DtoDefineFunction(symfd);
             
-        if (FuncDeclaration* fd = getParentFunc(sym->isFuncDeclaration(), true)) {
             // if this is for a function that doesn't access variables from
             // enclosing scopes, it doesn't matter what we pass.
             // Tell LLVM about it by passing an 'undef'.
-            if (fd->ir.irFunc->depth == 0)
+            if (symfd && symfd->ir.irFunc->depth == -1)
                 return llvm::UndefValue::get(getVoidPtrType());
             
+            // If sym is a nested function, and it's parent context is different than the
+            // one we got, adjust it.
+            if (FuncDeclaration* fd = getParentFunc(symfd, true)) {
                 Logger::println("For nested function, parent is %s", fd->toChars());
                 FuncDeclaration* ctxfd = irfunc->decl;
                 Logger::println("Current function is %s", ctxfd->toChars());
@@ -273,6 +277,7 @@ LLValue* DtoNestedContext(Loc loc, Dsymbol* sym)
                 }
             }
         }
+    }
     Logger::cout() << "result = " << *val << '\n';
     Logger::cout() << "of type " << *val->getType() << '\n';
     return val;
@@ -376,15 +381,15 @@ void DtoCreateNestedContext(FuncDeclaration* fd) {
             // start with adding all enclosing parent frames until a static parent is reached
             
             const LLStructType* innerFrameType = NULL;
-            unsigned depth = 0;
+            unsigned depth = -1;
             if (!fd->isStatic()) {
                 if (FuncDeclaration* parfd = getParentFunc(fd, true)) {
                     innerFrameType = parfd->ir.irFunc->frameType;
                     if (innerFrameType)
-                        depth = parfd->ir.irFunc->depth + 1;
+                        depth = parfd->ir.irFunc->depth;
                 }
             }
-            fd->ir.irFunc->depth = depth;
+            fd->ir.irFunc->depth = ++depth;
             
             Logger::cout() << "Function " << fd->toChars() << " has depth " << depth << '\n';
             

ir/irfunction.cpp

@@ -112,7 +112,7 @@ IrFunction::IrFunction(FuncDeclaration* fd)
 
     nestedVar = NULL;
     frameType = NULL;
-    depth = 0;
+    depth = -1;
     
     _arguments = NULL;
     _argptr = NULL;

ir/irfunction.h

@@ -46,7 +46,9 @@ struct IrFunction : IrBase
     
     llvm::Value* nestedVar; // nested var alloca
     const llvm::StructType* frameType; // type of nested context (not for -nested-ctx=array)
-    unsigned depth; // number of enclosing functions with variables accessed by nested functions
+    // number of enclosing functions with variables accessed by nested functions
+    // (-1 if neither this function nor any enclosing ones access variables from enclosing functions)
+    int depth;
     
     llvm::Value* _arguments;
     llvm::Value* _argptr;