I find our or32-elf-gcc works in a weird way, there is lots of redudnancy in the
complie result.

What I need is to move a byte value 35(0x23) to address 0x9000_0007. While from the
disassembled code, the compiler handle this task in a complex way, therefore the
code size is unnecessary big. Anybody can explain why gcc working like this?
and give some hint on how to solve this problem?

thanks a lot!!!

----------------- disassembled code (the comment are added by me)---------------------

#define REG8(add) *((volatile unsigned char *)(add))
#define MSG_UART_BR_LSB_ADDR 0x9000_0007

void msg_uart_init(void)
{
f4e4: 9c 21 ff d0 l.addi r1,r1,0xffffffd0
/* baud rate config */
REG8(MSG_UART_BR_LSB_ADDR) = 35;
f4e8: 18 60 90 00 l.movhi r3,0x9000 // load high address to r3 high part, then r3 = 0x9000_0000
f4ec: d4 01 18 20 l.sw 0x20(r1),r3 // store r3 to stack (@sp+0x20)
f4f0: 84 81 00 20 l.lwz r4,0x20(r1) // move stack (@sp+0x20) to r4
f4f4: a8 84 00 07 l.ori r4,r4,0x7 // r4|0x7, then r4 = 0x9000_0007, value of MSG_UART_BR_LSB_ADDR
f4f8: d4 01 20 24 l.sw 0x24(r1),r4 // store r4 to stack (@sp+0x24)
f4fc: 9c 60 00 23 l.addi r3,r0,0x23 // move 35(0x23) to r3
f500: d4 01 18 1c l.sw 0x1c(r1),r3 // move r3 to stack (@sp+0x1c)
f504: 84 81 00 1c l.lwz r4,0x1c(r1) // move stack (@sp+0x1c) to r4, now r4 = 0x23
f508: d8 01 20 1b l.sb 0x1b(r1),r4 // move r4 to stack (@sp+0x1b)
f50c: 8c 81 00 1b l.lbz r4,0x1b(r1) // load stack (@sp+0x1b) to r4
f510: 84 61 00 24 l.lwz r3,0x24(r1) // load stack (@sp+0x24) to r3
f514: d8 03 20 00 l.sb 0x0(r3),r4 // move r4(35) to address (EA)r3 (0x9000_0007)
REG8(MSG_UART_BR_MSB_ADDR) = 0;
f518: 18 60 90 00 l.movhi r3,0x9000
f51c: d4 01 18 14 l.sw 0x14(r1),r3
f520: 84 81 00 14 l.lwz r4,0x14(r1)
f524: a8 84 00 08 l.ori r4,r4,0x8
f528: d4 01 20 28 l.sw 0x28(r1),r4
.......

Please see the post "Bug in or32.h in GCC".
This fixes most of trash code.

hi,mikerez
Great, I will try your patch when I return to the lab, and
report the result later!

Thanks for your response!

bruce

Bruce

You seem to have posted this twice. My reply is in your other thread here.

Jeremy

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