re PR tree-optimization/84235 (Miscompilation of floating point code by dom2)

re PR tree-optimization/84235 (Miscompilation of floating point code by dom2)

	PR tree-optimization/84235
	* tree-ssa-scopedtables.c
	(avail_exprs_stack::simplify_binary_operation): Fir MINUS_EXPR, punt
	if the subtraction is performed in floating point type where NaNs are
	honored.  For *DIV_EXPR, punt for ALL_FRACT_MODE_Ps where we can't
	build 1.  Formatting fix.

	* gcc.c-torture/execute/ieee/pr84235.c: New test.

From-SVN: r257437