Fix PR target/35664

[Eric Botcazou]

This is an ICE compiling the kernel with -mno-fpu on the SPARC.  reload aborts 
because it is unable to find a register to spill in class 'FP_REGS', which is 
paradoxical since the insn involves integer values only:

(insn 166 123 140 
4 /home/ebotcazou/src-4.4/gcc/testsuite/gcc.target/sparc/pr35664.c:82 (set 
(reg:DI 262 [ <variable>.stats.ptc1522 ])
        (mem/s:DI (plus:SI (reg/v/f:SI 24 %i0 [orig:121 adapter ] [121])
                (reg:SI 4 %g4 [244])) [14 <variable>.stats.ptc1522+0 S8 A64])) 
45 {*movdi_insn_sp32} (expr_list:REG_EQUIV (mem/s:DI (plus:SI (reg/v/f:SI 
24 %i0 [orig:121 adapter ] [121])
                (reg:SI 4 %g4 [244])) [14 <variable>.stats.ptc1522+0 S8 A64])
        (nil)))

and -mno-fpu is used.  It turns out that reload will really choose an FP reg 
as a reload register in this case (DImode load with non-offsetable address) 
if -mno-fpu isn't specified, before eliminating it thanks to the REG_EQUIV.

Fixed by making constraints 'e' and 'f' return NO_REGS if -mno-fpu is used.
Tested on SPARC64/Linux and SPARC/Solaris, applied on mainline and 4.5/4.4 
branches.


2010-09-22  Eric Botcazou  <ebotcazou@adacore.com>

	PR target/35664
	* config/sparc/constraints.md ('e'): Return NO_REGS if !TARGET_FPU.
	('f'): Likewise.


2010-09-22  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc.target/sparc/mnofpu.c: New test.


-- 
Eric Botcazou
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