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Minor improvements in ARM stubs 

This gets rid of stack usage (except for callback invocations) in the
dynarec execution code. A requirement to make the dynarec re-entrant.
This commit is contained in:
David Guillen Fandos 2021-03-04 18:35:48 +01:00
parent f6ead0812a
commit 6770e0a5e7
1 changed files with 13 additions and 17 deletions
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30
arm/arm_stub.S
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@ -140,12 +140,8 @@
#define restore_flags() ;\
msr cpsr_f, reg_flags ;\
#ifdef __ARM_EABI__
@ must align stack
#define call_c_saved_regs r2, r3, r12, lr
#else
#define call_c_saved_regs r3, r12, lr
#endif
@ Align the stack to 64 bits (ABIs that don't require it, still recommend so)
#define call_c_saved_regs r2, r3, r12, lr
@ Calls a C function - all caller save registers which are important to the
@ dynarec and to returning from this function are saved.
@ -518,7 +514,7 @@ _execute_arm_translate:
#define execute_store_body(store_type, store_op) ;\
save_flags() ;\
stmdb sp!, { lr } /* save lr */;\
str lr, [reg_base, #REG_SAVE3] /* save lr */;\
tst r0, #0xF0000000 /* make sure address is in range */;\
bne ext_store_u##store_type /* if not do ext store */;\
;\
@ -558,18 +554,18 @@ _execute_store_u##store_type: ;\
;\
cmp r0, #0 /* see if it's not 0 */;\
bne 2f /* if so perform smc write */;\
ldmia sp!, { lr } /* restore lr */;\
ldr lr, [reg_base, #REG_SAVE3] /* restore lr */;\
restore_flags() ;\
add pc, lr, #4 /* return */;\
;\
2: ;\
ldmia sp!, { lr } /* restore lr */;\
ldr lr, [reg_base, #REG_SAVE3] /* restore lr */;\
ldr r0, [lr] /* load PC */;\
str r0, [reg_base, #REG_PC] /* write out PC */;\
b smc_write /* perform smc write */;\
;\
ext_store_u##store_type: ;\
ldmia sp!, { lr } /* pop lr off of stack */;\
ldr lr, [reg_base, #REG_SAVE3] /* pop lr off of stack */;\
ldr r2, [lr] /* load PC */;\
str r2, [reg_base, #REG_PC] /* write out PC */;\
store_align_##store_type() ;\
@ -587,10 +583,10 @@ execute_store_u32_safe:
_execute_store_u32_safe:
execute_store_body(32_safe, str)
restore_flags()
ldmia sp!, { pc } @ return
ldr pc, [reg_base, #REG_SAVE3] @ return
ext_store_u32_safe:
ldmia sp!, { lr } @ Restore lr
ldr lr, [reg_base, #REG_SAVE3] @ Restore lr
call_c_function(write_memory32) @ Perform 32bit store
restore_flags()
bx lr @ Return
@ -779,13 +775,13 @@ execute_gamepak_ptr:
cmp r1, #0 @ see if map entry is NULL
bne 2f @ if not resume
stmdb sp!, { r0 } @ save r0 on stack
str r0, [reg_base, #REG_SAVE2] @ save r0 on the temp memory
mov r2, r2, lsl #20 @ isolate page index
mov r0, r2, lsr #20
call_c_function(load_gamepak_page) @ read new page into r0
mov r1, r0 @ new map = return
ldmia sp!, { r0 } @ restore r0
ldr r0, [reg_base, #REG_SAVE2] @ restore r0
2:
mov r0, r0, lsl #17 @ isolate bottom 15 bits
@ -828,7 +824,7 @@ execute_open_ptr:
ldr r1, [reg_base, #REG_CPSR] @ r1 = cpsr
save_flags()
stmdb sp!, { r0 } @ save r0
str r0, [reg_base, #REG_SAVE2] @ save r0
ldr r0, [lr, #-4] @ r0 = current PC
@ -842,7 +838,7 @@ execute_open_ptr:
add r1, r1, reg_base
str r0, [r1] @ write out
ldmia sp!, { r0 } @ restore r0
ldr r0, [reg_base, #REG_SAVE2] @ restore r0
and r0, r0, #0x03 @ isolate bottom 2 bits
restore_flags()
@ -858,7 +854,7 @@ execute_open_ptr:
add r1, r1, reg_base
str r0, [r1] @ write out
ldmia sp!, { r0 } @ restore r0
ldr r0, [reg_base, #REG_SAVE2] @ restore r0
and r0, r0, #0x03 @ isolate bottom 2 bits
restore_flags();