From 025c5e6e8a7790887c3f36c949b52846032aca12 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sat, 28 Nov 2020 22:17:32 +0100
Subject: [PATCH] Added some more PIE/PIC code. Not quite correct yet
 unfortunately.

---
 src/build/build_options.c          | 19 +++++++++++++++++--
 src/build/build_options.h          | 19 +++++++++++++++----
 src/compiler/llvm_codegen_module.c | 14 ++++++++++++++
 src/compiler/target.c              |  2 +-
 4 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/src/build/build_options.c b/src/build/build_options.c
index 0e4698d22..38e97e1b0 100644
--- a/src/build/build_options.c
+++ b/src/build/build_options.c
@@ -277,14 +277,29 @@ static void parse_option(void)
 				build_options.feature.reg_struct_return = true;
 				return;
 			}
+			if (match_shortopt("fpie"))
+			{
+				build_options.pie = PIE_SMALL;
+				return;
+			}
+			if (match_shortopt("fPIE"))
+			{
+				build_options.pie = PIE_BIG;
+				return;
+			}
+			if (match_shortopt("fno-pie"))
+			{
+				build_options.pie = PIE_NONE;
+				return;
+			}
 			if (match_shortopt("fpic"))
 			{
-				build_options.pic = SMALL_PIC_USE;
+				build_options.pic = PIC_SMALL;
 				return;
 			}
 			if (match_shortopt("fPIC"))
 			{
-				build_options.pic = BIG_PIC_USE;
+				build_options.pic = PIC_BIG;
 				return;
 			}
 			if (match_shortopt("fno-pic"))
diff --git a/src/build/build_options.h b/src/build/build_options.h
index 99a899f29..1fe464dd1 100644
--- a/src/build/build_options.h
+++ b/src/build/build_options.h
@@ -88,14 +88,24 @@ typedef enum
 	SIZE_OPTIMIZATION_TINY = 2,     // -Oz
 } SizeOptimizationLevel;
 
+// Values correspond to LLVM values.
 typedef enum
 {
-	PIC_DEFAULT,
-	PIC_NONE,
-	BIG_PIC_USE,
-	SMALL_PIC_USE,
+	PIC_DEFAULT = -1,
+	PIC_NONE = 0,
+	PIC_SMALL = 1,
+	PIC_BIG = 2,
 } PicGeneration;
 
+// Values correspond to LLVM values
+typedef enum
+{
+	PIE_NONE = -1,
+	PIE_DEFAULT = 0,
+	PIE_SMALL = 1,
+	PIE_BIG = 2,
+} PieGeneration;
+
 typedef enum
 {
 	DEBUG_INFO_NONE,
@@ -137,6 +147,7 @@ typedef struct
 	const char* cpu;
 	const char* target_triple;
 	PicGeneration pic;
+	PieGeneration pie;
 	bool generate_lib;
 	struct
 	{
diff --git a/src/compiler/llvm_codegen_module.c b/src/compiler/llvm_codegen_module.c
index 9c611a0bd..edc509853 100644
--- a/src/compiler/llvm_codegen_module.c
+++ b/src/compiler/llvm_codegen_module.c
@@ -13,6 +13,20 @@ void gencontext_begin_module(GenContext *context)
 	context->module = LLVMModuleCreateWithNameInContext(mangled_module_name, context->context);
 	LLVMSetModuleDataLayout(context->module, target_data_layout());
 	LLVMSetSourceFileName(context->module, full_path, strlen(context->ast_context->file->full_path));
+	LLVMTypeRef options_type = LLVMInt8TypeInContext(context->context);
+
+	if (build_options.pic == PIC_BIG || build_options.pic == PIC_SMALL)
+	{
+		static const char *pic_level = "PIC Level";
+		LLVMMetadataRef setting = LLVMValueAsMetadata(LLVMConstInt(options_type, build_options.pic, false));
+		LLVMAddModuleFlag(context->module, LLVMModuleFlagBehaviorOverride, pic_level, strlen(pic_level), setting);
+	}
+	if (build_options.pie == PIE_BIG || build_options.pie == PIE_SMALL)
+	{
+		static const char *pie_level = "PIE Level";
+		LLVMMetadataRef setting = LLVMValueAsMetadata(LLVMConstInt(options_type, build_options.pie, false));
+		LLVMAddModuleFlag(context->module, LLVMModuleFlagBehaviorOverride, pie_level, strlen(pie_level), setting);
+	}
 
 	LLVMSetTarget(context->module, build_target.target_triple);
 	if (build_options.debug_info != DEBUG_INFO_NONE)
diff --git a/src/compiler/target.c b/src/compiler/target.c
index 11cb0e691..92102708a 100644
--- a/src/compiler/target.c
+++ b/src/compiler/target.c
@@ -419,7 +419,7 @@ void target_setup(void)
 		default:
 			UNREACHABLE;
 	}
-	 if (build_options.pic == BIG_PIC_USE || build_options.pic == SMALL_PIC_USE || build_options.generate_lib)
+	 if (build_options.pic == PIC_BIG || build_options.pic == PIC_SMALL || build_options.generate_lib)
 	 {
 	 	reloc_mode = LLVMRelocPIC;
 	 }