I am using C28x cgtools 6.01 and observed the following in a very small interrupt routine:
The compiler is saving all, even unused, registers.
Can I somehow avoid this?
Here is the code example:
interrupt void EPWM4_INT_ISRa(void)
{
EALLOW;
PWMModule3.TripZoneControl.Items.TZA = PWM_TZ_ACTION_FORCE_LOW;
PWMModule4.TripZoneControl.Items.TZA = PWM_TZ_ACTION_NONE;
PWMModule4.TripZoneClear.AsWord = 0xFFFF; // Re-enable PWM output + Interrupt
EDIS;
PIECtrl.ACK.AsWord = 0xFFFF;
PWMModule4.EventTriggerClear.Items.INT = 1;
}
With float_support=fpu32, it leads to
_EPWM4_INT_ISR:
;* AR4 assigned to $O$C1
ASP ; [CPU_]
PUSH RB ; [CPU_]
MOVL *SP++,XT ; [CPU_]
MOVL *SP++,XAR4 ; [CPU_]
MOVL *SP++,XAR5 ; [CPU_]
MOVL *SP++,XAR6 ; [CPU_]
MOVL *SP++,XAR7 ; [CPU_]
MOV32 *SP++,STF ; [CPU_]
MOV32 *SP++,R0H ; [CPU_]
MOV32 *SP++,R1H ; [CPU_]
MOV32 *SP++,R2H ; [CPU_]
MOV32 *SP++,R3H ; [CPU_]
SETFLG RNDF32=1, RNDF64=1 ; [CPU_]
CLRC PAGE0,OVM ; [CPU_]
CLRC AMODE ; [CPU_]
EALLOW
MOVL XAR4,#_PWMModule4 ; [CPU_U] |1177|
MOVL XAR5,XAR4 ; [CPU_] |1177|
ADDB XAR5,#20 ; [CPU_U] |1177|
OR *+XAR5[0],#0x0003 ; [CPU_] |1177|
EDIS
;----------------------------------------------------------------------
; 1183 | PWMModule4.EventTriggerClear.Items.INT = 1;
;----------------------------------------------------------------------
ADDB XAR4,#28 ; [CPU_U] |1183|
OR *+XAR4[0],#0x0001 ; [CPU_] |1183|
MOV32 R3H,*--SP ; [CPU_]
MOV32 R2H,*--SP ; [CPU_]
MOV32 R1H,*--SP ; [CPU_]
MOV32 R0H,*--SP ; [CPU_]
MOV32 STF,*--SP ; [CPU_]
MOVL XAR7,*--SP ; [CPU_]
MOVL XAR6,*--SP ; [CPU_]
MOVL XAR5,*--SP ; [CPU_]
MOVL XAR4,*--SP ; [CPU_]
MOVL XT,*--SP ; [CPU_]
POP RB ; [CPU_]
NASP ; [CPU_]
IRET ; [CPU_]
The RxH registers and XAR6,7 are definitely not used in the generated code, so why are they saved?
