simplify-rtx.c (simplify_binary_operation): Remove fall throughs.
* simplify-rtx.c (simplify_binary_operation) <UDIV, DIV, UMOD, MOD>:
Remove fall throughs. Convert 0/x and 0%x into x&0 when x has
side-effects. Don't convert x/1.0 into x if we honor signaling NaNs.
Convert x/-1.0 into -x if we don't honor signaling NaNs. Convert
x/-1 into -x. Optimize x%1 into x&0 if x has side-effects. Optimize
x%-1 into 0 (or x&0 if x has side-effects).