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ARMv7-M: FPU Register optimization
Improvement to the ARMv7-M port: FPU registers only saved/restored on context switch if they've been used by the task.
1 parent 0ab86bd commit 9a79718

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9 files changed

+83
-290
lines changed

9 files changed

+83
-290
lines changed

‎Ports/ARM-Cortex-M/ARMv7-M/ARM/os_cpu.h

Lines changed: 0 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -157,11 +157,6 @@ void OS_CPU_SysTickInitFreq(CPU_INT32U cpu_freq);
157157
void OS_CPU_SysTickHandler (void);
158158
void OS_CPU_PendSVHandler (void);
159159

160-
#if (OS_CPU_ARM_FP_EN > 0u)
161-
void OS_CPU_FP_Reg_Push (CPU_STK *stkPtr);
162-
void OS_CPU_FP_Reg_Pop (CPU_STK *stkPtr);
163-
#endif
164-
165160

166161
/*
167162
*********************************************************************************************************

‎Ports/ARM-Cortex-M/ARMv7-M/ARM/os_cpu_a.asm

Lines changed: 20 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -50,11 +50,6 @@
5050
EXPORT OSIntCtxSw
5151
EXPORT OS_CPU_PendSVHandler
5252

53-
IF {FPU} != "SoftVFP"
54-
EXPORT OS_CPU_FP_Reg_Push
55-
EXPORT OS_CPU_FP_Reg_Pop
56-
ENDIF
57-
5853

5954
;********************************************************************************************************
6055
; EQUATES
@@ -76,55 +71,6 @@ NVIC_PENDSVSET EQU 0x10000000 ; Value to trigg
7671
AREA CODE, CODE, READONLY
7772

7873

79-
;********************************************************************************************************
80-
; FLOATING POINT REGISTERS PUSH
81-
; void OS_CPU_FP_Reg_Push (CPU_STK *stkPtr)
82-
;
83-
; Note(s) : 1) This function saves S16-S31 registers of the Floating Point Unit.
84-
;
85-
; 2) Pseudo-code is:
86-
; a) Push remaining FPU regs S16-S31 on process stack;
87-
; b) Update OSTCBCurPtr->StkPtr;
88-
;********************************************************************************************************
89-
90-
IF {FPU} != "SoftVFP"
91-
92-
OS_CPU_FP_Reg_Push
93-
MRS R1, PSP ; PSP is process stack pointer
94-
CBZ R1, OS_CPU_FP_nosave ; Skip FP register save the first time
95-
96-
VSTMDB R0!, {S16-S31}
97-
LDR R1, =OSTCBCurPtr
98-
LDR R2, [R1]
99-
STR R0, [R2]
100-
OS_CPU_FP_nosave
101-
BX LR
102-
103-
ENDIF
104-
105-
106-
;********************************************************************************************************
107-
; FLOATING POINT REGISTERS POP
108-
; void OS_CPU_FP_Reg_Pop (CPU_STK *stkPtr)
109-
;
110-
; Note(s) : 1) This function restores S16-S31 of the Floating Point Unit.
111-
;
112-
; 2) Pseudo-code is:
113-
; a) Restore regs S16-S31 of new process stack;
114-
; b) Update OSTCBHighRdyPtr->StkPtr pointer of new proces stack;
115-
;********************************************************************************************************
116-
117-
IF {FPU} != "SoftVFP"
118-
119-
OS_CPU_FP_Reg_Pop
120-
VLDMIA R0!, {S16-S31}
121-
LDR R1, =OSTCBHighRdyPtr
122-
LDR R2, [R1]
123-
STR R0, [R2]
124-
BX LR
125-
126-
ENDIF
127-
12874

12975
;********************************************************************************************************
13076
; START MULTITASKING
@@ -177,6 +123,7 @@ OSStartHighRdy
177123

178124
MRS R0, CONTROL
179125
ORR R0, R0, #2
126+
BIC R0, R0, #4 ; Clear FPCA bit to indicate FPU is not in use
180127
MSR CONTROL, R0
181128
ISB ; Sync instruction stream
182129

@@ -265,6 +212,13 @@ OS_CPU_PendSVHandler
265212
CPSIE I
266213

267214
MRS R0, PSP ; PSP is process stack pointer
215+
IF {FPU} != "SoftVFP"
216+
; Push high vfp registers if the task is using the FPU context
217+
TST R14, #0x10
218+
IT EQ
219+
VSTMDBEQ R0!, {S16-S31}
220+
ENDIF
221+
268222
STMFD R0!, {R4-R11, R14} ; Save remaining regs r4-11, R14 on process stack
269223

270224
MOV32 R5, OSTCBCurPtr ; OSTCBCurPtr->StkPtr = SP;
@@ -287,10 +241,22 @@ OS_CPU_PendSVHandler
287241
ORR LR, R4, #0x04 ; Ensure exception return uses process stack
288242
LDR R0, [R2] ; R0 is new process SP; SP = OSTCBHighRdyPtr->StkPtr;
289243
LDMFD R0!, {R4-R11, R14} ; Restore r4-11, R14 from new process stack
244+
245+
IF {FPU} != "SoftVFP"
246+
; Pop the high vfp registers if the next task is using the FPU context
247+
TST R14, #0x10
248+
IT EQ
249+
VLDMIAEQ R0!, {S16-S31}
250+
ENDIF
251+
290252
MSR PSP, R0 ; Load PSP with new process SP
291253

292254
MOV32 R2, #0 ; Restore BASEPRI priority level to 0
255+
CPSID I ; Cortex-M7 errata notice. See Note #5
293256
MSR BASEPRI, R2
257+
DSB
258+
ISB
259+
CPSIE I
294260
BX LR ; Exception return will restore remaining context
295261

296262
ALIGN ; Removes warning[A1581W]: added <no_padbytes> of padding at <address>

‎Ports/ARM-Cortex-M/ARMv7-M/CCS/os_cpu.h

Lines changed: 0 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -157,11 +157,6 @@ void OS_CPU_SysTickInitFreq(CPU_INT32U cpu_freq);
157157
void OS_CPU_SysTickHandler (void);
158158
void OS_CPU_PendSVHandler (void);
159159

160-
#if (OS_CPU_ARM_FP_EN > 0u)
161-
void OS_CPU_FP_Reg_Push (CPU_STK *stkPtr);
162-
void OS_CPU_FP_Reg_Pop (CPU_STK *stkPtr);
163-
#endif
164-
165160

166161
/*
167162
*********************************************************************************************************

‎Ports/ARM-Cortex-M/ARMv7-M/CCS/os_cpu_a.asm

Lines changed: 20 additions & 58 deletions
Original file line numberDiff line numberDiff line change
@@ -59,11 +59,6 @@ OS_KA_BASEPRI_BoundaryAddr: .word OS_KA_BASEPRI_Boundary
5959
.global OSIntCtxSw
6060
.global OS_CPU_PendSVHandler
6161

62-
.if __TI_VFP_SUPPORT__
63-
.global OS_CPU_FP_Reg_Push
64-
.global OS_CPU_FP_Reg_Pop
65-
.endif
66-
6762

6863
;********************************************************************************************************
6964
; EQUATES
@@ -84,59 +79,6 @@ NVIC_PENDSVSET: .word 0x10000000 ; Value to trigg
8479
.thumb
8580

8681

87-
;********************************************************************************************************
88-
; FLOATING POINT REGISTERS PUSH
89-
; void OS_CPU_FP_Reg_Push (CPU_STK *stkPtr)
90-
;
91-
; Note(s) : 1) This function saves S16-S31 registers of the Floating Point Unit.
92-
;
93-
; 2) Pseudo-code is:
94-
; a) Push remaining FPU regs S16-S31 on process stack;
95-
; b) Update OSTCBCurPtr->StkPtr;
96-
;********************************************************************************************************
97-
98-
.if __TI_VFP_SUPPORT__
99-
.asmfunc
100-
OS_CPU_FP_Reg_Push:
101-
MRS R1, PSP ; PSP is process stack pointer
102-
CBZ R1, OS_CPU_FP_nosave ; Skip FP register save the first time
103-
104-
VSTMDB R0!, {S16-S31}
105-
LDR R1, OSTCBCurPtrAddr
106-
LDR R2, [R1]
107-
STR R0, [R2]
108-
.endasmfunc
109-
110-
.asmfunc
111-
OS_CPU_FP_nosave:
112-
BX LR
113-
.endasmfunc
114-
.endif
115-
116-
117-
;********************************************************************************************************
118-
; FLOATING POINT REGISTERS POP
119-
; void OS_CPU_FP_Reg_Pop (CPU_STK *stkPtr)
120-
;
121-
; Note(s) : 1) This function restores S16-S31 of the Floating Point Unit.
122-
;
123-
; 2) Pseudo-code is:
124-
; a) Restore regs S16-S31 of new process stack;
125-
; b) Update OSTCBHighRdyPtr->StkPtr pointer of new proces stack;
126-
;********************************************************************************************************
127-
128-
.if __TI_VFP_SUPPORT__
129-
.asmfunc
130-
OS_CPU_FP_Reg_Pop:
131-
VLDMIA R0!, {S16-S31}
132-
LDR R1, OSTCBHighRdyPtrAddr
133-
LDR R2, [R1]
134-
STR R0, [R2]
135-
BX LR
136-
.endasmfunc
137-
.endif
138-
139-
14082
;********************************************************************************************************
14183
; START MULTITASKING
14284
; void OSStartHighRdy(void)
@@ -189,6 +131,7 @@ OSStartHighRdy:
189131

190132
MRS R0, CONTROL
191133
ORR R0, R0, #2
134+
BIC R0, R0, #4 ; Clear FPCA bit to indicate FPU is not in use
192135
MSR CONTROL, R0
193136
ISB ; Sync instruction stream
194137

@@ -281,6 +224,13 @@ OS_CPU_PendSVHandler:
281224
CPSIE I
282225

283226
MRS R0, PSP ; PSP is process stack pointer
227+
.if __TI_VFP_SUPPORT__
228+
; Push high vfp registers if the task is using the FPU context
229+
TST R14, #0x10
230+
IT EQ
231+
VSTMDBEQ R0!, {S16-S31}
232+
.endif
233+
284234
STMFD R0!, {R4-R11, R14} ; Save remaining regs r4-11, R14 on process stack
285235

286236
LDR R5, OSTCBCurPtrAddr ; OSTCBCurPtr->StkPtr = SP;
@@ -303,10 +253,22 @@ OS_CPU_PendSVHandler:
303253
ORR LR, R4, #0x04 ; Ensure exception return uses process stack
304254
LDR R0, [R2] ; R0 is new process SP; SP = OSTCBHighRdyPtr->StkPtr;
305255
LDMFD R0!, {R4-R11, R14} ; Restore r4-11, R14 from new process stack
256+
257+
.if __TI_VFP_SUPPORT__
258+
; Pop the high vfp registers if the next task is using the FPU context
259+
TST R14, #0x10
260+
IT EQ
261+
VLDMIAEQ R0!, {S16-S31}
262+
.endif
263+
306264
MSR PSP, R0 ; Load PSP with new process SP
307265

308266
MOV R2, #0 ; Restore BASEPRI priority level to 0
267+
CPSID I ; Cortex-M7 errata notice. See Note #5
309268
MSR BASEPRI, R2
269+
DSB
270+
ISB
271+
CPSIE I
310272
BX LR ; Exception return will restore remaining context
311273
.endasmfunc
312274

‎Ports/ARM-Cortex-M/ARMv7-M/GNU/os_cpu.h

Lines changed: 0 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -157,11 +157,6 @@ void OS_CPU_SysTickInitFreq(CPU_INT32U cpu_freq);
157157
void OS_CPU_SysTickHandler (void);
158158
void OS_CPU_PendSVHandler (void);
159159

160-
#if (OS_CPU_ARM_FP_EN > 0u)
161-
void OS_CPU_FP_Reg_Push (CPU_STK *stkPtr);
162-
void OS_CPU_FP_Reg_Pop (CPU_STK *stkPtr);
163-
#endif
164-
165160

166161
/*
167162
*********************************************************************************************************

‎Ports/ARM-Cortex-M/ARMv7-M/GNU/os_cpu_a.S

Lines changed: 23 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,9 @@
1616
@
1717
@ ARMv7-M Port
1818
@
19+
@ File : os_cpu_a.asm
20+
@ Version : V3.08.00
21+
@********************************************************************************************************
1922
@ For : ARMv7-M Cortex-M
2023
@ Mode : Thumb-2 ISA
2124
@ Toolchain : GNU C Compiler
@@ -46,10 +49,6 @@
4649
.global OSIntCtxSw
4750
.global OS_CPU_PendSVHandler
4851

49-
#if (defined(__VFP_FP__) && !defined(__SOFTFP__))
50-
.global OS_CPU_FP_Reg_Push
51-
.global OS_CPU_FP_Reg_Pop
52-
#endif
5352

5453

5554
@********************************************************************************************************
@@ -72,56 +71,6 @@
7271
.syntax unified
7372

7473

75-
@********************************************************************************************************
76-
@ FLOATING POINT REGISTERS PUSH
77-
@ void OS_CPU_FP_Reg_Push (CPU_STK *stkPtr)
78-
@
79-
@ Note(s) : 1) This function saves S16-S31 registers of the Floating Point Unit.
80-
@
81-
@ 2) Pseudo-code is:
82-
@ a) Push remaining FPU regs S16-S31 on process stack;
83-
@ b) Update OSTCBCurPtr->StkPtr;
84-
@********************************************************************************************************
85-
86-
#if (defined(__VFP_FP__) && !defined(__SOFTFP__))
87-
88-
.thumb_func
89-
OS_CPU_FP_Reg_Push:
90-
MRS R1, PSP @ PSP is process stack pointer
91-
CBZ R1, OS_CPU_FP_nosave @ Skip FP register save the first time
92-
93-
VSTMDB R0!, {S16-S31}
94-
LDR R1, =OSTCBCurPtr
95-
LDR R2, [R1]
96-
STR R0, [R2]
97-
OS_CPU_FP_nosave:
98-
BX LR
99-
#endif
100-
101-
102-
@********************************************************************************************************
103-
@ FLOATING POINT REGISTERS POP
104-
@ void OS_CPU_FP_Reg_Pop (CPU_STK *stkPtr)
105-
@
106-
@ Note(s) : 1) This function restores S16-S31 of the Floating Point Unit.
107-
@
108-
@ 2) Pseudo-code is:
109-
@ a) Restore regs S16-S31 of new process stack;
110-
@ b) Update OSTCBHighRdyPtr->StkPtr pointer of new proces stack;
111-
@********************************************************************************************************
112-
113-
#if (defined(__VFP_FP__) && !defined(__SOFTFP__))
114-
115-
.thumb_func
116-
OS_CPU_FP_Reg_Pop:
117-
VLDMIA R0!, {S16-S31}
118-
LDR R1, =OSTCBHighRdyPtr
119-
LDR R2, [R1]
120-
STR R0, [R2]
121-
BX LR
122-
#endif
123-
124-
12574
@********************************************************************************************************
12675
@ START MULTITASKING
12776
@ void OSStartHighRdy(void)
@@ -182,6 +131,7 @@ OSStartHighRdy:
182131

183132
MRS R0, CONTROL
184133
ORR R0, R0, #2
134+
BIC R0, R0, #4 @ Clear FPCA bit to indicate FPU is not in use
185135
MSR CONTROL, R0
186136
ISB @ Sync instruction stream
187137

@@ -273,6 +223,13 @@ OS_CPU_PendSVHandler:
273223
CPSIE I
274224

275225
MRS R0, PSP @ PSP is process stack pointer
226+
#if (defined(__VFP_FP__) && !defined(__SOFTFP__))
227+
@ Push high vfp registers if the task is using the FPU context
228+
TST R14, #0x10
229+
IT EQ
230+
VSTMDBEQ R0!, {S16-S31}
231+
#endif
232+
276233
STMFD R0!, {R4-R11, R14} @ Save remaining regs r4-11, R14 on process stack
277234

278235
MOVW R5, #:lower16:OSTCBCurPtr @ OSTCBCurPtr->StkPtr = SP;
@@ -299,10 +256,22 @@ OS_CPU_PendSVHandler:
299256
ORR LR, R4, #0x04 @ Ensure exception return uses process stack
300257
LDR R0, [R2] @ R0 is new process SP; SP = OSTCBHighRdyPtr->StkPtr;
301258
LDMFD R0!, {R4-R11, R14} @ Restore r4-11, R14 from new process stack
259+
260+
#if (defined(__VFP_FP__) && !defined(__SOFTFP__))
261+
@ Pop the high vfp registers if the next task is using the FPU context
262+
TST R14, #0x10
263+
IT EQ
264+
VLDMIAEQ R0!, {S16-S31}
265+
#endif
266+
302267
MSR PSP, R0 @ Load PSP with new process SP
303268

304269
MOV R2, #0 @ Restore BASEPRI priority level to 0
270+
CPSID I @ Cortex-M7 errata notice. See Note #5
305271
MSR BASEPRI, R2
272+
DSB
273+
ISB
274+
CPSIE I
306275
BX LR @ Exception return will restore remaining context
307276

308277
.end

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