From 21be45a904a0afc767214298721bd2bbce19a054 Mon Sep 17 00:00:00 2001
From: hachem <im@hachem.wtf>
Date: Tue, 8 Sep 2026 11:26:42 +0200
Subject: feat: add signed memory loads

---
 src/codegen/nasm.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 2 deletions(-)

(limited to 'src/codegen/nasm.c')

diff --git a/src/codegen/nasm.c b/src/codegen/nasm.c
index 8bcdda3..198cb5c 100644
--- a/src/codegen/nasm.c
+++ b/src/codegen/nasm.c
@@ -14,6 +14,10 @@ static void emit_const_expr(struct Expr* expr, FILE* out)
 		case EXPR_PRIMARY:
 			fprintf(out, "%.*s", (int)expr->primary.token.length, expr->primary.token.start);
 			break;
+		case EXPR_UNARY:
+			fprintf(out, "%.*s", (int)expr->unary.op.length, expr->unary.op.start);
+			emit_const_expr(expr->unary.operand, out);
+			break;
 		case EXPR_BINARY:
 			emit_const_expr(expr->binary.left, out);
 			fprintf(out, " %.*s ", (int)expr->binary.op.length, expr->binary.op.start);
@@ -370,6 +374,14 @@ static bool fold_const(struct Program* program, struct Expr* expr, uint64_t* out
 						return fold_const(program, program->consts[i].value, out);
 			return false;
 		}
+		case EXPR_UNARY:
+		{
+			uint64_t value;
+			if (!fold_const(program, expr->unary.operand, &value))
+				return false;
+			*out = 0 - value;
+			return true;
+		}
 		case EXPR_BINARY:
 		{
 			uint64_t left;
@@ -470,6 +482,14 @@ static bool emit_operand(struct Emitter* emitter, struct Expr* expr)
 			fprintf(emitter->out, ".%.*s", (int)expr->member.member.length, expr->member.member.start);
 			return true;
 		}
+		case EXPR_UNARY:
+		{
+			uint64_t value;
+			if (!fold_const(emitter->program, expr, &value))
+				return false;
+			fprintf(emitter->out, "%lld", (long long)value);
+			return true;
+		}
 		case EXPR_BINARY:
 		case EXPR_DEREF:
 			return false;
@@ -536,10 +556,22 @@ static bool expr_supported(struct Emitter* emitter, struct Expr* expr)
 		case EXPR_MEMBER:
 		case EXPR_DEREF:
 			return true;
+		case EXPR_UNARY:
+		{
+			uint64_t value;
+			return fold_const(emitter->program, expr, &value);
+		}
 		case EXPR_BINARY:
 			if (expr->binary.right->kind != EXPR_PRIMARY &&
-				expr->binary.right->kind != EXPR_MEMBER)
+				expr->binary.right->kind != EXPR_MEMBER &&
+				expr->binary.right->kind != EXPR_UNARY)
 				return false;
+			if (expr->binary.right->kind == EXPR_UNARY)
+			{
+				uint64_t value;
+				if (!fold_const(emitter->program, expr->binary.right, &value))
+					return false;
+			}
 			if (expr->binary.right->kind == EXPR_PRIMARY &&
 				is_buffer_name(emitter, expr->binary.right->primary.token))
 				return false;
@@ -549,10 +581,35 @@ static bool expr_supported(struct Emitter* emitter, struct Expr* expr)
 	return false;
 }
 
-// dst = [address], zero-extending narrower loads into the full register
+// dst = [address], extending narrower loads into the full register. Unsigned
+// loads zero-extend (movzx / a 32-bit mov); signed loads sign-extend (movsx,
+// or movsxd for a dword).
 static void emit_load(struct Emitter* emitter, const char* dst, struct DerefExpr* deref)
 {
 	FILE* out = emitter->out;
+	if (deref->is_signed)
+	{
+		switch (deref->size)
+		{
+			case STORE_SIZE_BYTE:
+				fprintf(out, "\tmovsx %s, byte [", dst);
+				break;
+			case STORE_SIZE_WORD:
+				fprintf(out, "\tmovsx %s, word [", dst);
+				break;
+			case STORE_SIZE_DWORD:
+				fprintf(out, "\tmovsxd %s, dword [", dst);
+				break;
+			default:
+				fprintf(out, "\tmov %s, [", dst);
+				break;
+		}
+
+		emit_operand(emitter, deref->address);
+		fprintf(out, "]\n");
+		return;
+	}
+
 	switch (deref->size)
 	{
 		case STORE_SIZE_BYTE:
@@ -1073,6 +1130,9 @@ static void collect_floats_expr(struct FloatTable* floats, struct Expr* expr)
 		case EXPR_PRIMARY:
 			collect_float(floats, expr->primary.token);
 			break;
+		case EXPR_UNARY:
+			collect_floats_expr(floats, expr->unary.operand);
+			break;
 		case EXPR_BINARY:
 			collect_floats_expr(floats, expr->binary.left);
 			collect_floats_expr(floats, expr->binary.right);
-- 
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