Questionn: mul functions for v850e

[Kai Ruottu]

markku.pihlajamaa@luukku.com wrote:
> 
> Perhaps you should write -mv850e instead of -Wa,-mv850e.
> I have tried this (gcc version 2.96-xscale-010827)
> and seen a mul instruction in the assembly list.

 The Intel/RedHat XScale-sources are one solution, another is to try
to add the v850e/ea support to gcc-2.95.x.  GCC sources where the
support exists have been many and probably there are many now...

 Anyhow the address Markku forgot to announce is:

  http://developer.intel.com/design/intelxscale/dev_tools/010827/

 I haven't these sources yet, with a modem connection they are almost
impossible :-( or at least there must be some very important reason
for the download...).  Markku seems to have some rich friend with a
direct connection, 'no-cost' line at work or something...

> > -----Original Message-----
> > My question are:
> > 1) Does GNU 2.95.2 support v850e?

 No, when using the plain vanilla FSF sources.

> > 2) Why does not GCC generate muliply code sets?
> >    GCC generates __mulsi3 sub routine call.

 Maybe because v850 doesn't have this instruction code but v850e and
v850ea have it (I'm not a big V850-expert...)

> > 3) Please show me how to generate multiply code sets for v850e!

 As Markku suggested, change your GCC version into another one or try
to copy the v850e/ea support to your current gcc-2.95.x sources. Then
use the '-mv850e' option for 'v850e'.

> > v850-elf/bin/gcc -c -S -Wall -Wno-format -Wimplicit -Wparentheses \
> > -Wunused -fconserve-space -fno-exceptions -fno-rtti -O2 \
> > -fno-expensive-optimizations -mno-pro \
> > log-function -gstabs3 -ffixed-r20 -ffixed-r21 -fpack-struct \
> > -Wa,-mv850e mul.c

 I took the '-gstabs3' away, added the '-mv850e' and got for your:

> >   int func(int b)
> >   {
> >       return~b;
> >   }
> >
> >   int main()
> >   {
> >
> >       int a= 3;
> >       int b= 4;
> >       int c;
> >
> >       c= a * func(b);
> >       return c;
> >   }

the following output from my patched gcc-2.95.3-1 :

----------------- clip ----------------------------
	.file	"v850e-mul.c"
gcc2_compiled.:
	.section .text
	.align 1
	.global _func
	.type	 _func,@function
_func:
	not r6,r10
	jmp [r31]
.Lfe1:
	.size	 _func,.Lfe1-_func
	.align 1
	.global _main
	.type	 _main,@function
_main:
	addi -20,sp,sp
	st.w r31,16[sp]
	mov 4,r6
	jarl _func,r31
	mov 3,r11
	ld.w 16[sp],r31
	mul r11,r10,r0
	addi 20,sp,sp
	jmp [r31]
.Lfe2:
	.size	 _main,.Lfe2-_main
	.ident	"GCC: (GNU) 2.95.3-1 20010315 (release)"
----------------- clip ----------------------------

 So your:

> >         mov 3,r6
> >         mov r10,r7
> >         jarl ___mulsi3,r31
> >         ld.w 16[sp],r31

was replaced by:

	mov 3,r11
	ld.w 16[sp],r31
	mul r11,r10,r0

BTW, my gcc-2.95.3-1 generated identical code with yours gcc-2.95.2
without the '-mv850e'...

Cheers (Kampai?), Kai



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