Also do the BP dance if no spills occur

This is because arguments are annoyingly generated relative to
BP, which fails completely if the stack frame is not set up nicely.
TODO do stuff relative to SP so BP is just a general purpose register.

2 files changed, 10 insertions, 4 deletions

diff --git a/test/t2.c b/test/t2.c
index 11ce9b8..0f9432c 100644
--- a/test/t2.c
+++ b/test/t2.c
@@ -14,6 +14,7 @@ void main() {
 		mov b, @dir
 		hwi 1  // legs
 	}
+	holo_dec(dir);
 	dir = dir + 1;
 	if (dir == 4) dir = 0;
 }
diff --git a/to_assembly.c b/to_assembly.c
index bd680b3..6f40e2d 100644
--- a/to_assembly.c
+++ b/to_assembly.c
@@ -81,13 +81,18 @@ static void fix_function(struct ir *ir, int startidx, struct allocation *ral) {
 	}
 
 	free(offsets);
-	
-	if (spillspace == 0) return;
+
+	// TODO: Really, nothing should be relative to BP, instead everything should use SP. That
+	// would completely eliminate this BP dance anyway.
+
+	// if (spillspace == 0) return;
 
 	ir_insert_before(ir, startidx + 0, irins_make_1(INS_PUSH, ref_reg(REG_BP)));
 	ir_insert_before(ir, startidx + 1, irins_make_01(INS_MOV, ref_reg(REG_BP), ref_reg(REG_SP)));
-	ir_insert_before(ir, startidx + 2,
-			irins_make_012(INS_SUB, ref_reg(REG_SP), ref_reg(REG_SP), ref_imm(spillspace)));
+	if (spillspace != 0) {
+		ir_insert_before(ir, startidx + 2,
+				irins_make_012(INS_SUB, ref_reg(REG_SP), ref_reg(REG_SP), ref_imm(spillspace)));
+	}
 
 	for (int idx = startidx + 1; idx < ir->len; idx++) {
 		struct irins *ins = ir->inss[idx];