Error in Supporting Char and Int Addition.

Error in Supporting Char and Int Addition.

[Prashant Purohit]

Hi all,

        I have defined patterns for "movqi", "movsi", "addsi3" to support
character data type.

        I am getting the expected output when it comes to simple char
assignment operation.

        But when I try to add one char data type with another char or one
char data type with another int data type, I am getting extra load and store
which are not expected.

         For example,
************  test.c  ************
         char a, b;
        
         a = 'a';

         b = a + 10;
***********************************
        In normal case, considering ARM architecture as reference, the
assembly will be :

************  Arm Assembly *************

        mov     r3, #97
        strb    r3, [fp, #-14]
        ldrb    r3, [fp, #-14]
        add     r3, r3, #10
        strb    r3, [fp, #-13]

**********************************************
        But in case of my target I am getting extra load and store for the
addition line, i.e. before addition, it is storing char variable data type
in some other memory location with Store QI and then loading with Load SI
and then doing addition. Also, after addition it is doing extra store and
load. i.e storing the addition result with Store SI and loading the addition
result again with Load QI.
which can be seen in following assembly ( My Target assembly is converted in
to ARM assembly for reference) :

********** My Target Assembly  *************

	mov	r3,#97	 
	strb	r3, [fp, #-14]	 
	ldrb	r3, [fp, #-14]	 
	strb	r3, [fp, #-20]  /* Extra Store QI */	 
	ldr	r3, [fp, #-20]  /* Extra Load SI */
	add	r3, r3, #10
	str	r3, [fp, #-24]  /* Extra Store SI */
	ldrb	r3, [fp, #-24]  /* Extra Load QI */
	strb	r3, [fp, #-13]  	 

********************************************

        Any help in this regard is appreciated.

        Thanks in advance,

Regards,
Prashant


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Re: Error in Supporting Char and Int Addition.

[John (Eljay) Love-Jensen]

Hi Prashant,

I was unable to reproduce.

What was your compile command line?

What version of GCC are you using?

Sincerely,
--Eljay

Re: Error in Supporting Char and Int Addition.

[Prashant Purohit]

Hi Eljay,

    Thanks for reply.

    GCC version I am using is 4.3.0

    And to compile the C code I am using -S option to see the assembly file
for both ARM & my target architecture i.e. 

      # /Install_Path/arm-elf-gcc -S test.c

    And my problem is I am getting extra load and store instruction for my
target which is not there in case of ARM supported by GCC -4.3.0 which I
have mentioned in detail in first post.

Thanks & Regards,
Prashant.


John (Eljay) Love-Jensen wrote:
> 
> Hi Prashant,
> 
> I was unable to reproduce.
> 
> What was your compile command line?
> 
> What version of GCC are you using?
> 
> Sincerely,
> --Eljay
> 
> 
> 

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RE: Error in Supporting Char and Int Addition.

[John (Eljay) Love-Jensen]

Hi Prashant,

Do you get the same results if you enable optimization?

Sincerely,
--Eljay