From a299de2265ae1fc2da31214725ea5bf399848319 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Thu, 28 Apr 2016 15:10:27 -0700
Subject: [PATCH] better alignment value for stack variables

fixes debug info sometimes not being available for parameters
---
 src/codegen.cpp  | 18 +++++++++---------
 src/zig_llvm.cpp |  4 ++++
 src/zig_llvm.hpp |  2 ++
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/codegen.cpp b/src/codegen.cpp
index 5410fdcea..487c3ba37 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -3547,25 +3547,25 @@ static void do_code_gen(CodeGen *g) {
 
             if (var->block_context->node->type == NodeTypeFnDef) {
                 assert(var->gen_arg_index >= 0);
+                TypeTableEntry *gen_type;
                 if (handle_is_ptr(var->type)) {
-                    TypeTableEntry *gen_type = fn_table_entry->type_entry->data.fn.gen_param_info[var->src_arg_index].type;
+                    gen_type = fn_table_entry->type_entry->data.fn.gen_param_info[var->src_arg_index].type;
                     var->value_ref = LLVMGetParam(fn, var->gen_arg_index);
-                    var->di_loc_var = LLVMZigCreateParameterVariable(g->dbuilder, var->block_context->di_scope,
-                            buf_ptr(&var->name), import->di_file, var->decl_node->line + 1,
-                            gen_type->di_type, !g->strip_debug_symbols, 0, var->gen_arg_index + 1);
                 } else {
+                    gen_type = var->type;
                     var->value_ref = LLVMBuildAlloca(g->builder, var->type->type_ref, buf_ptr(&var->name));
-                    uint64_t align_bytes = LLVMABISizeOfType(g->target_data_ref, var->type->type_ref);
+                    unsigned align_bytes = ZigLLVMGetPrefTypeAlignment(g->target_data_ref, var->type->type_ref);
                     LLVMSetAlignment(var->value_ref, align_bytes);
-                    var->di_loc_var = LLVMZigCreateAutoVariable(g->dbuilder, var->block_context->di_scope,
-                            buf_ptr(&var->name), import->di_file, var->decl_node->line + 1,
-                            var->type->di_type, !g->strip_debug_symbols, 0);
                 }
+                var->di_loc_var = LLVMZigCreateParameterVariable(g->dbuilder, var->block_context->di_scope,
+                        buf_ptr(&var->name), import->di_file, var->decl_node->line + 1,
+                        gen_type->di_type, !g->strip_debug_symbols, 0, var->gen_arg_index + 1);
 
             } else {
                 var->value_ref = LLVMBuildAlloca(g->builder, var->type->type_ref, buf_ptr(&var->name));
 
-                uint64_t align_bytes = LLVMABISizeOfType(g->target_data_ref, var->type->type_ref);
+
+                unsigned align_bytes = ZigLLVMGetPrefTypeAlignment(g->target_data_ref, var->type->type_ref);
                 LLVMSetAlignment(var->value_ref, align_bytes);
 
                 var->di_loc_var = LLVMZigCreateAutoVariable(g->dbuilder, var->block_context->di_scope,
diff --git a/src/zig_llvm.cpp b/src/zig_llvm.cpp
index 8e56ed3de..cc0b63d1c 100644
--- a/src/zig_llvm.cpp
+++ b/src/zig_llvm.cpp
@@ -641,6 +641,10 @@ void ZigLLVMAddModuleDebugInfoFlag(LLVMModuleRef module) {
     unwrap(module)->addModuleFlag(Module::Warning, "Debug Info Version", DEBUG_METADATA_VERSION);
 }
 
+unsigned ZigLLVMGetPrefTypeAlignment(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
+    return unwrap(TD)->getPrefTypeAlignment(unwrap(Ty));
+}
+
 //------------------------------------
 
 #include "buffer.hpp"
diff --git a/src/zig_llvm.hpp b/src/zig_llvm.hpp
index 2c3df900b..43a3e4729 100644
--- a/src/zig_llvm.hpp
+++ b/src/zig_llvm.hpp
@@ -152,6 +152,8 @@ void LLVMZigSetFastMath(LLVMBuilderRef builder_wrapped, bool on_state);
 
 void ZigLLVMAddFunctionAttr(LLVMValueRef fn, const char *attr_name, const char *attr_value);
 
+unsigned ZigLLVMGetPrefTypeAlignment(LLVMTargetDataRef TD, LLVMTypeRef Ty);
+
 
 // copied from include/llvm/ADT/Triple.h