Added optimized device builds and harden the Embedded toolchain setup in both the PlayDate bindings and HelloPlayDate example targets.

Examples/swift.mk

@@ -4,7 +4,7 @@ STACK_SIZE     = 61800
 # Locate the Playdate SDK
 SDK = ${PLAYDATE_SDK_PATH}
 ifeq ($(SDK),)
-SDK = $(shell egrep '^\s*SDKRoot' ~/.Playdate/config | head -n 1 | cut -c9-)
+SDK = $(shell sed -nE 's/^[[:space:]]*SDKRoot[[:space:]]+//p' ~/.Playdate/config | head -n 1)
 endif
 
 ifeq ($(SDK),)
@@ -28,18 +28,37 @@ else
 $(error Swift toolchain not found; set ENV value TOOLCHAINS (e.g. TOOLCHAINS=org.swift.59202403121a make))
 endif
 
+# Note: paths containing spaces are not supported (make word-splits them).
 GCC_INCLUDE_PATHS := $(shell $(CC) -E -Wp,-v -xc /dev/null 2>&1 | egrep '^ ' | xargs echo )
+ifeq ($(GCC_INCLUDE_PATHS),)
+$(error arm-none-eabi C headers not found; install the Arm GNU toolchain and ensure $(CC) is runnable)
+endif
+
 SWIFT_EXEC := "$(shell TOOLCHAINS=$(TOOLCHAINS) xcrun -f swiftc)"
+# With an unknown TOOLCHAINS id, xcrun silently falls back to Xcode's swiftc,
+# which lacks the Embedded ARM stdlib; fail early with a clear message.
+ifeq ($(findstring .xctoolchain,$(SWIFT_EXEC)),)
+$(error swiftc for toolchain "$(TOOLCHAINS)" not found (xcrun returned $(SWIFT_EXEC)); install a swift.org toolchain or set TOOLCHAINS)
+endif
 TOOLCHAIN_PATH := $(shell echo $(SWIFT_EXEC)|sed s'/.xctoolchain.*/.xctoolchain/')
 
 $(info Using Swift toolchain "$(TOOLCHAINS)" (from $(TOOLCHAIN_PATH)))
 
+# Optimization mode for Swift compiles. -Osize targets small code, which
+# suits the device's flash/RAM budget (measured 15% smaller than -O on the
+# HelloPlaydate example); override per-build for maximum speed instead:
+# `make SWIFT_OPT=-O`. For larger games, appending
+# `-Xfrontend -mergeable-symbols -Xfrontend -mergeable-traps` lets the
+# linker deduplicate stdlib code specialized into both the wrapper and the
+# game module.
+SWIFT_OPT ?= -Osize
+
 C_FLAGS := \
 	$(addprefix -I ,$(GCC_INCLUDE_PATHS)) \
 
 SWIFT_FLAGS := \
 	$(addprefix -Xcc , $(C_FLAGS)) \
-	-O \
+	$(SWIFT_OPT) \
 	-wmo -enable-experimental-feature Embedded \
 	-Xfrontend -disable-stack-protector \
 	-Xfrontend -function-sections \