On Fri, 2024-06-28 at 20:34 +0800, chenglulu wrote:
>
> 在 2024/6/28 下午8:25, Xi Ruoyao 写道:
> > Hi Richard,
> >
> > The late combine pass has triggered some FAILs on LoongArch and I'm
> > investigating. One of them is movcf2gr-via-fr.c. In
> > 315r.postreload:
> >
> > (insn 22 7 24 2 (set (reg:FCC 32 $f0 [87])
> > (reg:FCC 64 $fcc0 [87]))
> > "../gcc/gcc/testsuite/gcc.target/loongarch/movcf2gr-via-fr.c":9:12
> > 168 {movfcc_internal}
> > (nil))
> > (insn 24 22 8 2 (set (reg:FCC 4 $r4 [88])
> > (reg:FCC 32 $f0 [87]))
> > "../gcc/gcc/testsuite/gcc.target/loongarch/movcf2gr-via-fr.c":9:12
> > 168 {movfcc_internal}
> > (nil))
> >
> > The late combine pass combines these to:
> >
> > (insn 24 7 8 2 (set (reg:FCC 4 $r4 [88])
> > (reg:FCC 64 $fcc0 [87]))
> > "../gcc/gcc/testsuite/gcc.target/loongarch/movcf2gr-via-fr.c":9:12
> > 168 {movfcc_internal}
> > (nil))
> >
> > But we are using a FPR ($f0) here deliberately to work around an
> > architectural issue in LA464 causing a direct FCC-to-GPR move very
> > slow.
> >
> > Could you suggest how to fix this issue?
>
> Hi, Ruoyao:
>
> We need to define TARGET_INSN_COST and set the cost of
> movcf2gr/movgr2cf.
>
> I've fixed this and am doing correctness testing now.
Ah thanks! So it uses insn cost instead of rtx cost and I didn't
realize.
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University
