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[Bug target/52107] IBM 128bit long double constant loaded inefficiently
- From: "amodra at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 03 Feb 2012 23:17:36 +0000
- Subject: [Bug target/52107] IBM 128bit long double constant loaded inefficiently
- Auto-submitted: auto-generated
- References: <bug-52107-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52107
--- Comment #2 from Alan Modra <amodra at gmail dot com> 2012-02-03 23:17:36 UTC ---
.tc generates an 8-byte word in both cases, so no space saved in the toc. This
bit of code in rs6000_emit_move does the loads in DImode, then cse1 shows the
toc load being converted to a load immediate and it all goes downhill from
there.
/* 128-bit constant floating-point values on Darwin should really be
loaded as two parts. */
if (!TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128
&& mode == TFmode && GET_CODE (operands[1]) == CONST_DOUBLE)
{
/* DImode is used, not DFmode, because simplify_gen_subreg doesn't
know how to get a DFmode SUBREG of a TFmode. */