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[Bug target/61872] Assigning to "long double" causes memset to be improperly elided
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 23 Jul 2014 12:34:53 +0000
- Subject: [Bug target/61872] Assigning to "long double" causes memset to be improperly elided
- Auto-submitted: auto-generated
- References: <bug-61872-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61872
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |x86_64-*-*, i?86-*-*
Status|ASSIGNED |NEW
CC| |ebotcazou at gcc dot gnu.org
Component|c++ |target
Assignee|rguenth at gcc dot gnu.org |unassigned at gcc dot gnu.org
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Err, not exactly mine but the issue is that we have
(insn 6 5 7 (set (mem/c:DI (reg:DI 85) [0 MEM[(void *)&a]+0 S8 A128])
(const_int 0 [0])) t.c:5 -1
(nil))
(insn 7 6 0 (set (mem/c:DI (plus:DI (reg:DI 85)
(const_int 8 [0x8])) [0 MEM[(void *)&a]+8 S8 A64])
(const_int 0 [0])) t.c:5 -1
(nil))
...
(insn 9 8 0 (set (mem/c:XF (plus:DI (reg/f:DI 78 virtual-stack-vars)
(const_int -16 [0xfffffffffffffff0])) [0 a+0 S16 A128])
(float_extend:XF (reg:SF 86))) t.c:6 -1
(nil))
but the actual store via fstpt is _not_ 16 bytes. Thus the XFmode store
for some reason got a MEM_SIZE of 16. And RTL DSE only looks at MEM_SIZE.
And even the default mode_mem_attrs[XFmode] have 16 bytes size. And
mode_size[XFmode] is 16.
But
FRACTIONAL_FLOAT_MODE (XF, 80, 12, ieee_extended_intel_96_format);
?!
Making target dependent for now.