Returning a REGMODE_NATURAL_SIZE of 4 for DFmode in 64-bit mode is asking for 
trouble because sub-word SUBREGs are always treated differently than the 
others, in particular by the register allocator.

Bootstrapped/regtested on SPARC64/Linux and SPARC/Solaris, applied on the 
mainline.


2021-03-10  Eric Botcazou  <ebotcazou@adacore.com>

	* config/sparc/sparc.c (sparc_regmode_natural_size): Return 4 for
	float and vector integer modes only if the mode is not larger.

-- 
Eric Botcazou