fanqifei wrote:
> Is there anyone can help?
> I am curious about how the insv pattern can be used in the compiling process.
> Otherwise, I have to write inline assembly code.
Use __builtin_mips_insv (i32, i32)
Andrew.
> Thanks very much!
>
> 2009/12/16 fanqifei <fanqifei@xxxxxxxxx>:
>> Hello,
>> I am tring to compile a small c file using gcc4.1.2.
>> The source code:
>> struct test_foo {
>> unsigned int a:18;
>> unsigned int b:2;
>> unsigned int c:12;
>> };
>>
>> struct test_foo x;
>> unsigned int foo()
>> {
>> unsigned int a=x.b;
>> x.b=2;
>> return a;
>> }
>>
>> the command: mipsel-linux-gcc -mips32r2 -O2 -c -Wall foo.c -o foo.o
>>
>> The corresponding disassembly code:
>> foo.o: file format elf32-tradlittlemips
>> Disassembly of section .text:
>> 00000000 <foo>:
>> 0: 3c1c0000 lui gp,0x0
>> 4: 279c0000 addiu gp,gp,0
>> 8: 0399e021 addu gp,gp,t9
>> c: 8f850000 lw a1,0(gp)
>> 10: 3c03fff3 lui v1,0xfff3
>> 14: 3463ffff ori v1,v1,0xffff
>> 18: 8ca20000 lw v0,0(a1)
>> 1c: 3c040008 lui a0,0x8
>> 20: 00431824 and v1,v0,v1
>> 24: 00641825 or v1,v1,a0
>> 28: 7c420c80 ext v0,v0,0x12,0x2
>> 2c: 03e00008 jr ra
>> 30: aca30000 sw v1,0(a1)
>> The statement x.b=2 can be simply translated to lb and ins instructions( ins
>> is in mips32r2).
>>
>> I wonder how ins instrution can be produced.
>> More specifically, how can gcc generates the insv pattern in RTL?
>> Is it related to the coding style -- using bit filed or logical
>> operations(shift, and ...)?
>> Thanks.
>> Qifei
>>
>>
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