llvm dev - Apr 2013 - [LLVMdev] Instruction Implementation

hi all

I have a question about implementing a new instruction which does this
function f(x) = x + ceilf (x) .x is a single float 
i have already added the instruction in my backend in the .td file 

def SUBCEIL_S   : FFR<0x11, 0x3, 16, (outs  FGR32:$fd), (ins  FGR32:$fs),
"frac.s\t$fd, $fs", [(set (f32  FGR32:$fd), (fadd (f32  FGR32:$fs
),(f32
(ceilf FGR32:$fs))))] >;
it makes and install correctly but when i ll try to write code to use this
instruction there is no luck.

Should i do something in ISelLowering.cpp or ISelDAGToDAG.cpp file? my
backend is based on mips backend

thanks in Advance,

Stavropoulos Nikos



--
View this message in context:
http://llvm.1065342.n5.nabble.com/LLVMdev-Instruction-Implementation-tp56359.html
Sent from the LLVM - Dev mailing list archive at Nabble.com.

Hi,
> def SUBCEIL_S   : FFR<0x11, 0x3, 16, (outs  FGR32:$fd), (ins 
FGR32:$fs),
> "frac.s\t$fd, $fs", [(set (f32  FGR32:$fd), (fadd (f32  FGR32:$fs
),(f32
> (ceilf FGR32:$fs))))] >;
>
> it makes and install correctly but when i ll try to write code to use this
> instruction there is no luck.
More details (including the .ll source and *how* exactly things are
going wrong) would be useful. Does llc crash? Does it simply not
select your code even though there's an fceil in the DAG? Is there no
fceil node in the DAG (run llc with "-view-isel-dags")?

Assuming the "ceilf" is a typo, my wild stab in the dark would be that
you've got code something like:

define float @foo(float %in) {
  %1 = tail call float @ceilf(float %in)
  ret float %1
}

declare float @ceilf(float)

and haven't given the "@ceilf" function the attribute
"readonly". This
is what LLVM uses (in many cases) to decide whether the call is a
known library call and can be transformed into an appropriate ISD
node.

Tim.

Hi and thanks for answering

llc works fine just does not selecting my instruction 

i ve uploaded .ll file

how can i include this attribute "readonly" so i can see if changes
the
generated assembly?


my code is very simple
int main (){
float d, d1 ;
        d= 12.3;
        d1 = d - ceilf(d);

return 0;
}



--
View this message in context:
http://llvm.1065342.n5.nabble.com/LLVMdev-Instruction-Implementation-tp56359p56377.html
Sent from the LLVM - Dev mailing list archive at Nabble.com.