https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97073
Uroš Bizjak <ubizjak at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|target |middle-end
--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
Middle-end expands double mode operation to:
2: r85:DI=[r76:SI]
3: NOTE_INSN_FUNCTION_BEG
6: r86:SI=`gs2'
7: r87:SI=`gs2'
10: {r89:SI=r85:DI#0&[r87:SI];clobber flags:CC;}
11: [r86:SI+0x4]=r89:SI
14: {r91:SI=r85:DI#4&[r87:SI+0x4];clobber flags:CC;}
15: [r86:SI+0x8]=r91:SI
Please note how (insn 11) partially clobbers input value, needed by (insn 14).
When -msse2 is used, we expand with:
6: r86:SI=`gs2'
7: r87:SI=`gs2'
10: {r89:DI=r85:DI&[r87:SI];clobber flags:CC;}
11: [r86:SI+0x4]=r89:DI
that bypasses generic middle-end expansion.
