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Re: [PATCH] Better checking of ISA/ASE/ABI options for MIPS gas
Richard Sandiford wrote:
[snip]
> > - /* ??? GAS treats single-float processors as though they had 64-bit
> > - float registers (although it complains when double-precision
> > - instructions are used). As things stand, saying they have 32-bit
> > - registers would lead to spurious "register must be even" messages.
> > - So here we assume float registers are always the same size as
> > - integer ones, unless the user says otherwise. */
> > - if (file_mips_fp32 < 0)
> > - file_mips_fp32 = file_mips_gp32;
> > + switch (file_mips_fp32)
> > + {
> > + default:
> > + case -1:
> > + /* No user specified float register size. */
> > + if (file_mips_gp32 == 0)
> > + /* 64-bit integer registers implies 64-bit float registers. */
> > + file_mips_fp32 = 0;
> > + else if ((mips_opts.ase_mips3d > 0 || mips_opts.ase_mdmx > 0)
> > + && ISA_HAS_64BIT_FPRS (mips_opts.isa))
> > + /* -mips3d and -mdmx imply 64-bit float registers, if possible. */
> > + file_mips_fp32 = 0;
> > + else
> > + /* 32-bit float registers. */
> > + file_mips_fp32 = 1;
> > + break;
> > +
> > + /* The user specified the size of the float registers. Check if it
> > + agrees with the ABI and ISA. */
> > + case 0:
> > + if (!ISA_HAS_64BIT_FPRS (mips_opts.isa))
> > + as_bad (_("-mfp64 used with a 32-bit fpu"));
> > + else if (ABI_NEEDS_32BIT_REGS (mips_abi)
> > + && !ISA_HAS_MXHC1 (mips_opts.isa))
> > + as_warn (_("-mfp64 used with a 32-bit ABI"));
> > + break;
> > + case 1:
> > + if (ABI_NEEDS_64BIT_REGS (mips_abi))
> > + as_warn (_("-mfp32 used with a 64-bit ABI"));
> > + break;
> > + }
>
> Doesn't the ??? comment still hold? I thought it would be valuable
> to keep it.
The defaulting is now more complicated than the comment suggests.
> > + else if (strcmp (name, "gp64") == 0)
> > + {
> > + if (!ISA_HAS_64BIT_REGS (mips_opts.isa))
> > + as_warn ("%s isa does not support 64-bit registers",
> > + mips_cpu_info_from_isa (mips_opts.isa)->name);
> > + mips_opts.gp32 = 0;
> > + }
> > + else if (strcmp (name, "gp32") == 0)
> > + {
> > + mips_opts.gp32 = 1;
> > + }
> > + else if (strcmp (name, "nogp64") == 0 || strcmp (name, "nogp32") == 0)
> > + {
> > + mips_opts.gp32 = file_mips_gp32;
> > + }
>
> Ugh. I don't like the "nogp32" and "nogp64".
Well, it is what MIPS' SDE toolchain supports.
> All other ".set X"/".set noX"
> pairs are used for turning a particular feature on and off. Having "nogp32"
> restore the prevailing size (even if that prevailing size _is_ gp32)
> seems very counter-intuitive to me. Could we not have ".set gp=" instead,
> with a special value to select the prevailing size? That would be more
> consistent with .set mipsX and .set arch=X, for example.
Hm, .set gp={32,64,default} or .set gp{32,64,0} ?
Thiemo