From 4a05e69e19455677a3847433dc76b7775c478166 Mon Sep 17 00:00:00 2001
From: bricky149 <shane.bundy@outlook.com>
Date: Wed, 4 Oct 2023 22:24:07 +0100
Subject: [PATCH] Retain space saving benefits when not using LTO

---
 Makefile    | 10 ++++++++++
 firmware.ld |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 303ec81..273ac07 100644
--- a/Makefile
+++ b/Makefile
@@ -170,9 +170,14 @@ CFLAGS = -Os -Wall -Werror -mcpu=cortex-m0 -fno-builtin -fshort-enums -fno-delet
 ifeq ($(ENABLE_LTO), 1)
 #	CFLAGS += -flto
 	CFLAGS += -flto=2
+else
+#	We get most of the space savings if LTO creates problems
+	CFLAGS += -ffunction-sections -fdata-sections
 endif
 
+# May cause unhelpful build failures
 #CFLAGS += -Wpadded
+
 CFLAGS += -DPRINTF_INCLUDE_CONFIG_H
 CFLAGS += -DGIT_HASH=\"$(GIT_HASH)\"
 ifeq ($(ENABLE_SWD),1)
@@ -280,6 +285,11 @@ LDFLAGS = -mcpu=cortex-m0 -nostartfiles -Wl,-T,firmware.ld
 # Use newlib-nano instead of newlib
 LDFLAGS += --specs=nano.specs
 
+ifeq ($(ENABLE_LTO), 0)
+#	Throw away unneeded func/data sections like LTO does
+	LDFLAGS += -Wl,--gc-sections
+endif
+
 ifeq ($(DEBUG),1)
 	ASFLAGS += -g
 	CFLAGS += -g
diff --git a/firmware.ld b/firmware.ld
index c00d2ba..a7bd16b 100644
--- a/firmware.ld
+++ b/firmware.ld
@@ -17,7 +17,7 @@ SECTIONS
 	.text :
 	{
 		. = ALIGN(4);
-		*(.text.isr)           /* .text sections of code  */
+		KEEP(*(.text.isr)) /* .text sections of code  */
 		*(.text)           /* .text sections of code  */
 		*(.text*)          /* .text* sections of code */
 		*(.rodata)         /* .rodata sections        */