[coreboot] Compile error in coreboot-v2: "failed to trunc value: mask ff"

[Marc Jones]

Cory,
I don't know what the error means. Others might know more but I can make 
some recommendations for you to try.
ROMCC problems are usually a stack depth problem. ROMCC is using 
registers for stack space so every function call uses up registers. The 
code around this code will have a big effect if this code will work. 
First try to inline the code (ROMCC might already be doing this). Next, 
try moving the pci read to after the math so the value doesn't need to 
be stored before it is used.

Marc

Corey Osgood wrote:
> Working with romcc here, you can drop this block of code into the 
> auto.c/raminit portion of any board using romcc and reproduce the 
> error (it compiles fine with CAR, but that's not an option with the c7 
> cpu, at least not yet):
>
> u8 reg8, spd_data;
>
> reg8 = pci_read_config8(PCI_DEV(0, 0, 3), 0x62);
> spd_data = smbus_read_byte(0x50, 30);
> spd_data = spd_data / 10;
> if(spd_data < 5)
>     spd_data = 5;
> else if(spd_data > 20)
>     spd_data = 20;
>
> if(spd_data > (reg8 >> 4))
> {
>    reg8 &= 0xf;
>    reg8 |= (spd_data << 4);
> }
>
> The error is confirmed on ubuntu 8.04 alpha/beta/? and debian 
> unstable, both with gcc 4.2.3, and also gentoo with gcc 4.1.2:
>
> dst type: auto unsigned char
> dst: %edx:%eax
> auto.c:35.1: raminit.c:436.33: raminit.c:615.36: auto.c:218.32:
> 0x83cbe70 convert    Internal compiler error: failed to trunc value: 
> mask ff
> make[1]: *** [auto.inc] Aborted (core dumped)
>
> Commenting out either spd_data/10 or the if/else portion gets rid of 
> the error, it only happens when all of these statements are in. I also 
> have half a dozen blocks like this which compile fine:
>
>     reg8 = pci_read_config8(ctrl->d0f3, 0x63);
>     j = spd_read_byte(ctrl->channel0[i], SPD_tRRD);//ctrl->channel0[0] 
> = 0x50
>     spd_data = ((j >> 2) * 100);
>     spd_data |= ((j & 0x3) * 25);
>     spd_data = spd_data / (ram_cycle * 100); //ram_cycle in this case = 10
>     if(spd_data < 2)
>         spd_data = 2;
>     else if(spd_data > 5)
>         spd_data = 5;
>
>     if((spd_data - 2) > (reg8 >> 6)) {
>         reg8 &= 0x3f;
>         reg8 |= (spd_data - 2) << 6;
>     }
>
> It's just that one instance that fails to compile. I've tried moving 
> it around, changing the variables, changing the types, modifying the 
> math, etc, etc, and nothing seems to help. Any suggestions?

-- 
Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com
http://www.amd.com/embeddedprocessors