From c8ab1b7ee1b1ba6444a057c6afa6a9d6eb7a7dae Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Sun, 24 Jul 2022 13:11:48 +0100
Subject: [PATCH] Add `#by_ptr` procedure attribute to enforce a parameter to
 be passed by pointer internally

---
 src/check_type.cpp           | 20 +++++++++++++++++++-
 src/entity.cpp               |  1 +
 src/llvm_backend_general.cpp |  5 +++--
 src/parser.cpp               |  2 ++
 src/parser.hpp               |  3 ++-
 5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/check_type.cpp b/src/check_type.cpp
index 741385e29..dea523599 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -1616,6 +1616,10 @@ Type *check_get_params(CheckerContext *ctx, Scope *scope, Ast *_params, bool *is
 					error(name, "'#any_int' can only be applied to variable fields");
 					p->flags &= ~FieldFlag_any_int;
 				}
+				if (p->flags&FieldFlag_by_ptr) {
+					error(name, "'#by_ptr' can only be applied to variable fields");
+					p->flags &= ~FieldFlag_by_ptr;
+				}
 
 				param = alloc_entity_type_name(scope, name->Ident.token, type, EntityState_Resolved);
 				param->TypeName.is_type_alias = true;
@@ -1692,10 +1696,17 @@ Type *check_get_params(CheckerContext *ctx, Scope *scope, Ast *_params, bool *is
 
 				if (p->flags&FieldFlag_no_alias) {
 					if (!is_type_pointer(type)) {
-						error(name, "'#no_alias' can only be applied to fields of pointer type");
+						error(name, "'#no_alias' can only be applied pointer typed parameters");
 						p->flags &= ~FieldFlag_no_alias; // Remove the flag
 					}
 				}
+				if (p->flags&FieldFlag_by_ptr) {
+					if (is_type_internally_pointer_like(type)) {
+						error(name, "'#by_ptr' can only be applied to non-pointer-like parameters");
+						p->flags &= ~FieldFlag_by_ptr; // Remove the flag
+					}
+				}
+
 				if (is_poly_name) {
 					if (p->flags&FieldFlag_no_alias) {
 						error(name, "'#no_alias' can only be applied to non constant values");
@@ -1713,6 +1724,10 @@ Type *check_get_params(CheckerContext *ctx, Scope *scope, Ast *_params, bool *is
 						error(name, "'#const' can only be applied to variable fields");
 						p->flags &= ~FieldFlag_const;
 					}
+					if (p->flags&FieldFlag_by_ptr) {
+						error(name, "'#by_ptr' can only be applied to variable fields");
+						p->flags &= ~FieldFlag_by_ptr;
+					}
 
 					if (!is_type_constant_type(type) && !is_type_polymorphic(type)) {
 						gbString str = type_to_string(type);
@@ -1745,6 +1760,9 @@ Type *check_get_params(CheckerContext *ctx, Scope *scope, Ast *_params, bool *is
 			if (p->flags&FieldFlag_const) {
 				param->flags |= EntityFlag_ConstInput;
 			}
+			if (p->flags&FieldFlag_by_ptr) {
+				param->flags |= EntityFlag_ByPtr;
+			}
 
 			param->state = EntityState_Resolved; // NOTE(bill): This should have be resolved whilst determining it
 			add_entity(ctx, scope, name, param);
diff --git a/src/entity.cpp b/src/entity.cpp
index 76e6912b9..3d3712328 100644
--- a/src/entity.cpp
+++ b/src/entity.cpp
@@ -83,6 +83,7 @@ enum EntityFlag : u64 {
 	EntityFlag_CustomLinkage_LinkOnce = 1ull<<44,
 	
 	EntityFlag_Require = 1ull<<50,
+	EntityFlag_ByPtr = 1ull<<51, // enforce parameter is passed by pointer
 
 	EntityFlag_Overridden    = 1ull<<63,
 };
diff --git a/src/llvm_backend_general.cpp b/src/llvm_backend_general.cpp
index b2a609f85..a4c2ce370 100644
--- a/src/llvm_backend_general.cpp
+++ b/src/llvm_backend_general.cpp
@@ -1958,11 +1958,12 @@ LLVMTypeRef lb_type_internal(lbModule *m, Type *type) {
 					if (e->flags & EntityFlag_CVarArg) {
 						continue;
 					}
-
 					Type *e_type = reduce_tuple_to_single_type(e->type);
 
 					LLVMTypeRef param_type = nullptr;
-					if (is_type_boolean(e_type) &&
+					if (e->flags & EntityFlag_ByPtr) {
+						param_type = lb_type(m, alloc_type_pointer(e_type));
+					} else if (is_type_boolean(e_type) &&
 					    type_size_of(e_type) <= 1) {
 						param_type = LLVMInt1TypeInContext(m->ctx);
 					} else {
diff --git a/src/parser.cpp b/src/parser.cpp
index dd9d6f036..247255ce8 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -3561,6 +3561,7 @@ enum FieldPrefixKind : i32 {
 	FieldPrefix_auto_cast,
 	FieldPrefix_any_int,
 	FieldPrefix_subtype, // does not imply `using` semantics
+	FieldPrefix_by_ptr,
 };
 
 struct ParseFieldPrefixMapping {
@@ -3578,6 +3579,7 @@ gb_global ParseFieldPrefixMapping parse_field_prefix_mappings[] = {
 	{str_lit("const"),      Token_Hash,      FieldPrefix_const,     FieldFlag_const},
 	{str_lit("any_int"),    Token_Hash,      FieldPrefix_any_int,   FieldFlag_any_int},
 	{str_lit("subtype"),    Token_Hash,      FieldPrefix_subtype,   FieldFlag_subtype},
+	{str_lit("by_ptr"),     Token_Hash,      FieldPrefix_by_ptr,    FieldFlag_by_ptr},
 };
 
 
diff --git a/src/parser.hpp b/src/parser.hpp
index 8719b5e56..3126e0a02 100644
--- a/src/parser.hpp
+++ b/src/parser.hpp
@@ -302,13 +302,14 @@ enum FieldFlag : u32 {
 	FieldFlag_const     = 1<<5,
 	FieldFlag_any_int   = 1<<6,
 	FieldFlag_subtype   = 1<<7,
+	FieldFlag_by_ptr    = 1<<8,
 
 	// Internal use by the parser only
 	FieldFlag_Tags      = 1<<10,
 	FieldFlag_Results   = 1<<16,
 
 	// Parameter List Restrictions
-	FieldFlag_Signature = FieldFlag_ellipsis|FieldFlag_using|FieldFlag_no_alias|FieldFlag_c_vararg|FieldFlag_auto_cast|FieldFlag_const|FieldFlag_any_int,
+	FieldFlag_Signature = FieldFlag_ellipsis|FieldFlag_using|FieldFlag_no_alias|FieldFlag_c_vararg|FieldFlag_auto_cast|FieldFlag_const|FieldFlag_any_int|FieldFlag_by_ptr,
 	FieldFlag_Struct    = FieldFlag_using|FieldFlag_subtype|FieldFlag_Tags,
 };