From 5effb5bfcaf95ad12e42a298c2306fab36dd402e Mon Sep 17 00:00:00 2001
From: Camil Staps
Date: Sun, 2 Oct 2016 12:05:50 +0000
Subject: Fix storing the program counter

The previous solution was to add 9 (8 for the offset, 1 for the Thumb
state). However, the lowest bit is used for something else (garbage
collection / evaluation status), so this gives some problems.
This solution adds only 8 (the offset), so that we don't alter the
lowest two bits. Then, when jumping, the address is IORed with 1, so
that the Thumb state bit is set.
---
 cgthumb2was.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/cgthumb2was.c b/cgthumb2was.c
index 334bd16..4881263 100644
--- a/cgthumb2was.c
+++ b/cgthumb2was.c
@@ -1486,7 +1486,7 @@ static void w_as_jsr_instruction (struct instruction *instruction)
 				case P_INDIRECT_WITH_UPDATE:
 					w_as_instruction_without_parameters (".align");
 					w_as_opcode ("add");
-					fprintf (assembly_file,"lr,pc,#9");
+					fprintf (assembly_file,"lr,pc,#8");
 					w_as_newline_after_instruction();
 					w_as_opcode ("str");
 					fprintf (assembly_file,"lr,[sp,#%d]!",instruction->instruction_parameters[1].parameter_offset);
@@ -1500,20 +1500,18 @@ static void w_as_jsr_instruction (struct instruction *instruction)
 		if (instruction->instruction_arity>1)
 			w_as_instruction_without_parameters (".align");
 			w_as_opcode ("add");
-			w_as_scratch_register_comma();
-			fprintf (assembly_file,"pc,#9");
+			fprintf (assembly_file,"lr,pc,#%d",
+					instruction->instruction_parameters[0].parameter_type==P_REGISTER ? 6 : 8);
 			w_as_newline_after_instruction();
 			switch (instruction->instruction_parameters[1].parameter_type){
 				case P_INDIRECT_WITH_UPDATE:
 					w_as_opcode ("str");
-					w_as_scratch_register_comma();
-					fprintf (assembly_file,"[sp,#%d]!",instruction->instruction_parameters[1].parameter_offset);
+					fprintf (assembly_file,"lr,[sp,#%d]!",instruction->instruction_parameters[1].parameter_offset);
 					w_as_newline_after_instruction();
 					break;
 				case P_INDIRECT:
 					w_as_opcode ("str");
-					w_as_scratch_register_comma();
-					fprintf (assembly_file,"[sp,#%d]",instruction->instruction_parameters[1].parameter_offset);
+					fprintf (assembly_file,"lr,[sp,#%d]",instruction->instruction_parameters[1].parameter_offset);
 					w_as_newline_after_instruction();
 					break;
 			}
@@ -2315,7 +2313,13 @@ static void w_as_fmovel_instruction (struct instruction *instruction)
 static void w_as_rts_instruction (void)
 {
 	w_as_opcode ("ldr");
-	fprintf (assembly_file,"pc,[sp],#4");
+	fprintf (assembly_file,"lr,[sp],#4");
+	w_as_newline_after_instruction();
+	w_as_opcode ("orr");
+	fprintf (assembly_file,"lr,lr,#1");
+	w_as_newline_after_instruction();
+	w_as_opcode ("mov");
+	fprintf (assembly_file,"pc,lr");
 	w_as_newline_after_instruction();
 
 	write_float_constants();
-- 
cgit v1.2.3