1. Improve 32bit FP performance significantly on current
x86 processors without changing Makefiles. SPEC CPU
FP can be improved by as much as 20%.
2. A new psABI designed for SSE math won't happen
in the foreseeable future. -with-math=sse provides a
a way to improve FP performance with backward binary
compatibility.
3. The performance gain is automatic since it requires
very few changes in software packages if any changes
are needed at all.
4. MacOS chose Linux psABI with SSE math enabled by
default and increased alignment when they defined a new
psABI. It is an indication that SSE math can be used on
entire OS with improved FP performance.
OK for trunk?