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Make codebase more friendly to modern ARM compilers #2271

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497ee84
Make codebase more friendly to modern ARM compilers
SiliconA-Z Apr 5, 2026
22b7864
makefile: For modern, use -fno-strict-aliasing
SiliconA-Z Mar 23, 2026
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6 changes: 4 additions & 2 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,7 @@ else
MODERNCC := $(PREFIX)gcc
PATH_MODERNCC := PATH="$(PATH)" $(MODERNCC)
CC1 := $(shell $(PATH_MODERNCC) --print-prog-name=cc1) -quiet
override CFLAGS += -mthumb -mthumb-interwork -O$(O_LEVEL) -mabi=apcs-gnu -mtune=arm7tdmi -march=armv4t -fno-toplevel-reorder -Wno-pointer-to-int-cast
override CFLAGS += -mthumb -mthumb-interwork -O$(O_LEVEL) -mabi=apcs-gnu -mtune=arm7tdmi -march=armv4t -fno-strict-aliasing -Wno-pointer-to-int-cast
LIBPATH := -L "$(dir $(shell $(PATH_MODERNCC) -mthumb -print-file-name=libgcc.a))" -L "$(dir $(shell $(PATH_MODERNCC) -mthumb -print-file-name=libnosys.a))" -L "$(dir $(shell $(PATH_MODERNCC) -mthumb -print-file-name=libc.a))"
LIB := $(LIBPATH) -lc -lnosys -lgcc -L../../libagbsyscall -lagbsyscall
endif
Expand Down Expand Up @@ -293,7 +293,9 @@ $(C_BUILDDIR)/record_mixing.o: CFLAGS += -ffreestanding
$(C_BUILDDIR)/librfu_intr.o: CC1 := $(TOOLS_DIR)/agbcc/bin/agbcc_arm$(EXE)
$(C_BUILDDIR)/librfu_intr.o: CFLAGS := -O2 -mthumb-interwork -quiet
else
$(C_BUILDDIR)/librfu_intr.o: CFLAGS := -mthumb-interwork -O2 -mabi=apcs-gnu -mtune=arm7tdmi -march=armv4t -fno-toplevel-reorder -Wno-pointer-to-int-cast
$(C_BUILDDIR)/m4a.o: CFLAGS += -fno-toplevel-reorder
$(C_BUILDDIR)/librfu_intr.o: CFLAGS := -mthumb-interwork -O2 -mabi=apcs-gnu -mtune=arm7tdmi -march=armv4t -fno-toplevel-reorder -fno-strict-aliasing -Wno-pointer-to-int-cast
$(C_BUILDDIR)/agb_flash.o: CFLAGS += -fno-toplevel-reorder
$(C_BUILDDIR)/berry_crush.o: override CFLAGS += -Wno-address-of-packed-member
endif

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3 changes: 2 additions & 1 deletion include/gba/types.h
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Expand Up @@ -2,6 +2,7 @@
#define GUARD_GBA_TYPES_H

#include <stdint.h>
#include "gba/defines.h"

typedef uint8_t u8;
typedef uint16_t u16;
Expand Down Expand Up @@ -69,7 +70,7 @@ struct OamData
u16 priority:2; // 0x400, 0x800 -> 0xC00
u16 paletteNum:4;
/*0x06*/ u16 affineParam;
};
} ALIGNED(4); // Modern compilers will use wrong align-of sometimes.

#define ST_OAM_HFLIP 0x08
#define ST_OAM_VFLIP 0x10
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9 changes: 5 additions & 4 deletions include/global.h
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Expand Up @@ -17,11 +17,12 @@
#include "constants/easy_chat.h"
#include "constants/trainer_hill.h"

// Prevent cross-jump optimization.
#define BLOCK_CROSS_JUMP asm("");

// to help in decompiling
// Unified Thumb/ARM asm. Modern (Clang): no .syntax divided — Clang rejects it. Legacy agbcc output still expects divided after the block.
#if MODERN
#define asm_unified(x) asm(".syntax unified\n" x)
#else
#define asm_unified(x) asm(".syntax unified\n" x "\n.syntax divided")
#endif
#define NAKED __attribute__((naked))

#if MODERN
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14 changes: 7 additions & 7 deletions src/multiboot.c
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Expand Up @@ -441,16 +441,16 @@ static void MultiBootWaitCycles(u32 cycles)
{
asm_unified("\
mov r2, pc\n\
lsrs r2, 24\n\
movs r1, 12\n\
cmp r2, 2\n\
lsrs r2, r2, #24\n\
movs r1, #12\n\
cmp r2, #2\n\
beq MultiBootWaitCyclesLoop\n\
movs r1, 13\n\
cmp r2, 8\n\
movs r1, #13\n\
cmp r2, #8\n\
beq MultiBootWaitCyclesLoop\n\
movs r1, 4\n\
movs r1, #4\n\
MultiBootWaitCyclesLoop:\n\
subs r0, r1\n\
subs r0, r0, r1\n\
bgt MultiBootWaitCyclesLoop\n\
bx lr\n");
}
Expand Down