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* [Bug tree-optimization/60989] New: automatic increase of global array for vectorization doesn't work due to flag_section_anchors==0
@ 2014-04-28 15:21 andi-gcc at firstfloor dot org
2014-04-28 15:28 ` [Bug tree-optimization/60989] " jakub at gcc dot gnu.org
2014-04-29 0:18 ` andi-gcc at firstfloor dot org
0 siblings, 2 replies; 3+ messages in thread
From: andi-gcc at firstfloor dot org @ 2014-04-28 15:21 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60989
Bug ID: 60989
Summary: automatic increase of global array for vectorization
doesn't work due to flag_section_anchors==0
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: andi-gcc at firstfloor dot org
Target x86_64-linux
Following simple test case:
#define N 64
#define ALIGN // __attribute__((aligned(64)))
int a[N] ALIGN;
int b[N] ALIGN;
main()
{
int i;
for (i = 0; i < N; i++)
a[i] = b[i] + 1;
}
If I leave the ALIGN commented out I get really horrible manual alignment
prologue code like
-O3 -mavx512f
.cfi_startproc
movl $a, %eax
andl $63, %eax
shrq $2, %rax
negq %rax
andl $15, %eax
je .L7
movl b(%rip), %edi
cmpl $1, %eax
leal 1(%rdi), %edx
movl %edx, a(%rip)
je .L8
...
lots of repeats upto 63
With ALIGN it's a nice short perfectly vectorized loop.
It seems the automatic alignment of global variables doesn't work anymore.
I checked the increase_alignment/ipa_increase_alignment pass in
tree-vectorize.c and both don't run because flag_section_anchors is 0 in the
gate.
I'm not fully sure what the flag means?
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/60989] automatic increase of global array for vectorization doesn't work due to flag_section_anchors==0
2014-04-28 15:21 [Bug tree-optimization/60989] New: automatic increase of global array for vectorization doesn't work due to flag_section_anchors==0 andi-gcc at firstfloor dot org
@ 2014-04-28 15:28 ` jakub at gcc dot gnu.org
2014-04-29 0:18 ` andi-gcc at firstfloor dot org
1 sibling, 0 replies; 3+ messages in thread
From: jakub at gcc dot gnu.org @ 2014-04-28 15:28 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60989
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
You need C++ or -fno-common. Common variables really can't have alignment
increased by the compiler.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/60989] automatic increase of global array for vectorization doesn't work due to flag_section_anchors==0
2014-04-28 15:21 [Bug tree-optimization/60989] New: automatic increase of global array for vectorization doesn't work due to flag_section_anchors==0 andi-gcc at firstfloor dot org
2014-04-28 15:28 ` [Bug tree-optimization/60989] " jakub at gcc dot gnu.org
@ 2014-04-29 0:18 ` andi-gcc at firstfloor dot org
1 sibling, 0 replies; 3+ messages in thread
From: andi-gcc at firstfloor dot org @ 2014-04-29 0:18 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60989
Andi Kleen <andi-gcc at firstfloor dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #2 from Andi Kleen <andi-gcc at firstfloor dot org> ---
Ok fair enough.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-04-29 0:18 UTC | newest]
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2014-04-28 15:21 [Bug tree-optimization/60989] New: automatic increase of global array for vectorization doesn't work due to flag_section_anchors==0 andi-gcc at firstfloor dot org
2014-04-28 15:28 ` [Bug tree-optimization/60989] " jakub at gcc dot gnu.org
2014-04-29 0:18 ` andi-gcc at firstfloor dot org
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