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How to run cm.jalt instruction of Zcmt Extension in Embench-iot programs by Spike? #229
Comments
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I changed my code a liitle (spike) r 40
core 0: 0x00001000 (0x00000297) auipc t0, 0x0
core 0: 0x00001004 (0x02028593) addi a1, t0, 32
core 0: 0x00001008 (0xf1402573) csrr a0, mhartid
core 0: 0x0000100c (0x0182a283) lw t0, 24(t0)
core 0: 0x00001010 (0x00028067) jr t0
core 0: 0x80000000 (0x00000001) c.nop
core 0: 0x80000002 (0x00004081) c.li ra, 0
core 0: 0x80000004 (0x00004101) c.li sp, 0
core 0: 0x80000006 (0x00004181) c.li gp, 0
core 0: 0x80000008 (0x00004201) c.li tp, 0
core 0: 0x8000000a (0x00004281) c.li t0, 0
core 0: 0x8000000c (0x00004301) c.li t1, 0
core 0: 0x8000000e (0x00004381) c.li t2, 0
core 0: 0x80000010 (0x00004401) c.li s0, 0
core 0: 0x80000012 (0x00004481) c.li s1, 0
core 0: 0x80000014 (0x00004501) c.li a0, 0
core 0: 0x80000016 (0x00004581) c.li a1, 0
core 0: 0x80000018 (0x00004601) c.li a2, 0
core 0: 0x8000001a (0x00004681) c.li a3, 0
core 0: 0x8000001c (0x00004701) c.li a4, 0
core 0: 0x8000001e (0x00004781) c.li a5, 0
core 0: 0x80000020 (0x00004801) c.li a6, 0
core 0: 0x80000022 (0x00004881) c.li a7, 0
core 0: 0x80000024 (0x00004901) c.li s2, 0
core 0: 0x80000026 (0x00004981) c.li s3, 0
core 0: 0x80000028 (0x00004a01) c.li s4, 0
core 0: 0x8000002a (0x00004a81) c.li s5, 0
core 0: 0x8000002c (0x00004b01) c.li s6, 0
core 0: 0x8000002e (0x00004b81) c.li s7, 0
core 0: 0x80000030 (0x00004c01) c.li s8, 0
core 0: 0x80000032 (0x00004c81) c.li s9, 0
core 0: 0x80000034 (0x00004d01) c.li s10, 0
core 0: 0x80000036 (0x00004d81) c.li s11, 0
core 0: 0x80000038 (0x00004e01) c.li t3, 0
core 0: 0x8000003a (0x00004e81) c.li t4, 0
core 0: 0x8000003c (0x00004f01) c.li t5, 0
core 0: 0x8000003e (0x00004f81) c.li t6, 0
core 0: 0x80000040 (0x80100137) lui sp, 0x80100
core 0: 0x80000044 (0x800102b7) lui t0, 0x80010
core 0: 0x80000048 (0x04028293) addi t0, t0, 64
(spike)
core 0: 0x8000004c (0x01729073) csrw jvt, t0
(spike)
core 0: 0x80000050 (0x00004281) c.li t0, 0
(spike)
core 0: 0x80000052 (0x0000a1a6) cm.jalt 105
(spike)
core 0: exception trap_instruction_access_fault, epc 0x00000000
core 0: tval 0x00000000
(spike)
core 0: exception trap_instruction_access_fault, epc 0x00000000
core 0: tval 0x00000000Now I just need to manually add the function pointer to JVT? |
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If you could give me a simple example using zcmt, I would be very happy. |
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according to psabi you need to add https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc |
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Thank you so much for telling me. ↓crt0.s .section .text.init
.globl _start
_start:
nop
li x1, 0
li x2, 0
li x3, 0
li x4, 0
li x5, 0
li x6, 0
li x7, 0
li x8, 0
li x9, 0
li x10, 0
li x11, 0
li x12, 0
li x13, 0
li x14, 0
li x15, 0
li x16, 0
li x17, 0
li x18, 0
li x19, 0
li x20, 0
li x21, 0
li x22, 0
li x23, 0
li x24, 0
li x25, 0
li x26, 0
li x27, 0
li x28, 0
li x29, 0
li x30, 0
li x31, 0
# set the stack pointer 64 KiB
li sp, 0x80100000
# set the jvt csr
1: auipc a0, %pcrel_hi(__jvt_base$)
addi a0, a0, %pcrel_lo(1b)
csrw jvt, a0
li a0, 0
jal main
# shutdown
li t0, 1
sw t0, tohost, t1
1: j 1b
put_string:
li t0, 0
1: lbu t1, (a0)
beqz t1, 1f
or t1, t1, t0
sw t0, tohost, t2
addi a0, a0, 1
j 1b
1: ret
.globl start_trigger
start_trigger:
la a0, str_start
j put_string
.globl stop_trigger
stop_trigger:
la a0, str_stop
j put_string
.section .tohost
.align 6
.globl tohost
tohost: .dword 0
.align 6
.globl fromhost
fromhost: .dword 0
.section .riscv.jvt
__jvt_base$: .dword 0
.section .rodata
.align 4
str_start:
.string "start!\n"
.align 4
str_stop:
.string "stop!\n"
.align 4↓link.ld I changed crt0.s & link.ld in this way. It still does not seem to generate a valid jump table. Could you be more specific...? |
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Get rid of this: and define it as a linker symbol: |
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Embench is too small to make any use of Zcmt. The linker should auto relax jumps to the correct entries in the table and auto fill the table once you have had its location defined as recomended (If and only if it thinks that it will be able to save code size doing so). In your dissassembly I see a cm.jalt 105. I doubt this was a result of a linker relaxation. If the intention is to simply test Zcmt, then you need to fill the table manually with correct addresses pointing to functions for a directed test. Otherwise I would get a larger benchmark to test with ! |
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I appreciate it. I changed like this. ↓crt0.s .section .text.init
.globl _start
_start:
nop
li x1, 0
li x2, 0
li x3, 0
li x4, 0
li x5, 0
li x6, 0
li x7, 0
li x8, 0
li x9, 0
li x10, 0
li x11, 0
li x12, 0
li x13, 0
li x14, 0
li x15, 0
li x16, 0
li x17, 0
li x18, 0
li x19, 0
li x20, 0
li x21, 0
li x22, 0
li x23, 0
li x24, 0
li x25, 0
li x26, 0
li x27, 0
li x28, 0
li x29, 0
li x30, 0
li x31, 0
# set the stack pointer 64 KiB
li sp, 0x80100000
# set the jvt csr
1: auipc a0, %pcrel_hi(__jvt_base$)
addi a0, a0, %pcrel_lo(1b)
csrw jvt, a0
li a0, 0
jal main
# shutdown
li t0, 1
sw t0, tohost, t1
1: j 1b
put_string:
li t0, 0
1: lbu t1, (a0)
beqz t1, 1f
or t1, t1, t0
sw t0, tohost, t2
addi a0, a0, 1
j 1b
1: ret
.globl start_trigger
start_trigger:
la a0, str_start
j put_string
.globl stop_trigger
stop_trigger:
la a0, str_stop
j put_string
.section .tohost
.align 6
.globl tohost
tohost: .dword 0
.align 6
.globl fromhost
fromhost: .dword 0
.section .rodata
.align 4
str_start:
.string "start!\n"
.align 4
str_stop:
.string "stop!\n"
.align 4↓link.ld But I couldn't execute on Spike. As the contributor says, is the linker not generating the jump table because the embench is too small to use zcmt? |
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@abukharmeh I have a few questions. What is relaxation for a linker? Why is the jump instruction compiled as cm.jalt 105 when linker has determined that Zcmt is ineffective in reducing code size? You mentioned that we should manually create a jump table to test the zcmt. You also say that another alternative is that we should use a larger benchmark, what is the specific benchmark? |
The concern is that a tbljal to a single entry has a net negative size reduction, and there is at least 105 of those on a benchmark that tends to be massively inlined. You can show also the most recent output + spike messages. |
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One more thing: on eclipse CDT build, after changing anything in linker files, you have to do a project clean and modify&save at least one of the project source files. Otherwise the old linker file is somehow still in use. Not sure how it works in raw compilations. |
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also initialization of the global pointer is missing |
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Thanks a lot. These are flags for compilers and linkers Since the jump table did not exist, the spike message was not useful information.
Sorry, I did not know how to improve on this↑ part...
So, how do we initialize the global pointer? I am not quite sure about the role of the global pointer... |
It should be enough, normally it's done like like this: https://github.com/openwch/ch32v003/blob/main/EVT/EXAM/SRC/Ld/Link.ld#L117 |
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I set up gp as you said, but it failed to compile... .section .text.init
.globl _start
_start:
nop
li x1, 0
li x2, 0
li x3, 0
li x4, 0
li x5, 0
li x6, 0
li x7, 0
li x8, 0
li x9, 0
li x10, 0
li x11, 0
li x12, 0
li x13, 0
li x14, 0
li x15, 0
li x16, 0
li x17, 0
li x18, 0
li x19, 0
li x20, 0
li x21, 0
li x22, 0
li x23, 0
li x24, 0
li x25, 0
li x26, 0
li x27, 0
li x28, 0
li x29, 0
li x30, 0
li x31, 0
# Recommended way to initialize the gp register.
.option push
.option norelax
1: auipc gp, %pcrel_hi(__global_pointer$)
addi gp, gp, %pcrel_lo(1b)
.option pop
# set the stack pointer 64 KiB
li sp, 0x80014000
# set the jvt csr
1: auipc a0, %pcrel_hi(__jvt_base$)
addi a0, a0, %pcrel_lo(1b)
csrw jvt, a0
li a0, 0
jal main
# shutdown
li t0, 1
sw t0, tohost, t1
1: j 1blink.ld Could you please tell me what the difference is? Sorry for repeating myself. I appreciate it. |
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what is the compilation log? |
This is part of the compilation log. |
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ah, semicolon missing should be |
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Compilation and linking succeeded, but no jump table was generated and execution with spike failed... |
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what are the logs and decompilation now? |
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compilation logs |
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I meant the error logs and disassembly |
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You mean error logs of spike? |
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yes, but first: seems like jvt_base is emmitted implicitly in text section, so try to remove from linker script |
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I tried it but... compilation logs spike logs |
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ah, back to this. |
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spike does not output any information on terminal ... |
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I tried to run cm.jalt instruction of Zcmt Extension in Embench-iot programs by Spike, but I can't.
I asked same content in riscv-isa-sim repository, but I didn't make sense...
command↓
spike --isa=rv32ima_zicsr_zca_zcb_zcmp_zcmt -d cubic(cubic is elf file)
the console output↓
Tell me how to solve this problem.
I could run Zca,Zcb,Zcmp instructions by Spike without any problems.
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