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* [Bug target/67127] New: [ARM] Avoiding odd-number ldrd/strd in movdi introduced a regression on armeb-linux-gnueabihf
@ 2015-08-05 13:23 yroux at gcc dot gnu.org
2015-08-12 13:28 ` [Bug target/67127] " yroux at gcc dot gnu.org
2015-08-17 11:27 ` yroux at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: yroux at gcc dot gnu.org @ 2015-08-05 13:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67127
Bug ID: 67127
Summary: [ARM] Avoiding odd-number ldrd/strd in movdi
introduced a regression on armeb-linux-gnueabihf
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: yroux at gcc dot gnu.org
Target Milestone: ---
Hi,
Commit r225461 which avoids odd-number ldrd/strd in movdi, and its backport on
gcc-5-branch (r225467) introduced several segfault (stack overflow) in the
testsuite when the compiler is built for big-endian + vfp targets.
The issue is that the movdi pattern calls gen_lowpart (SImode, operands[0]),
operands being in DImode, but the mode of the register cannot be changed as it
is explained in the macro CANNOT_CHANGE_MODE_CLASS definition:
"In big-endian mode, modes greater than word size (i.e. DFmode) are stored in
VFP registers in little-endian order. We can't describe that accurately to
GCC, so avoid taking subregs of such values."
Thus, gen_lowpart_general makes a copy of that register and copy it, which
calls again emit_move_insn and gen_movdi and so on ...
I've a patch under test that prevent doing this when the mode of a register
can't be changed, but the regression discussed in this thread may be back
then...
https://gcc.gnu.org/ml/gcc-patches/2015-07/msg00216.html
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/67127] [ARM] Avoiding odd-number ldrd/strd in movdi introduced a regression on armeb-linux-gnueabihf
2015-08-05 13:23 [Bug target/67127] New: [ARM] Avoiding odd-number ldrd/strd in movdi introduced a regression on armeb-linux-gnueabihf yroux at gcc dot gnu.org
@ 2015-08-12 13:28 ` yroux at gcc dot gnu.org
2015-08-17 11:27 ` yroux at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: yroux at gcc dot gnu.org @ 2015-08-12 13:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67127
--- Comment #1 from Yvan Roux <yroux at gcc dot gnu.org> ---
Author: yroux
Date: Wed Aug 12 13:27:41 2015
New Revision: 226811
URL: https://gcc.gnu.org/viewcvs?rev=226811&root=gcc&view=rev
Log:
2015-08-12 Yvan Roux <yvan.roux@linaro.org>
PR target/67127
* config/arm/arm.md (movdi): Restrict illegitimate ldrd/strd checking
to ARM core registers.
Modified:
trunk/gcc/ChangeLog
trunk/gcc/config/arm/arm.md
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/67127] [ARM] Avoiding odd-number ldrd/strd in movdi introduced a regression on armeb-linux-gnueabihf
2015-08-05 13:23 [Bug target/67127] New: [ARM] Avoiding odd-number ldrd/strd in movdi introduced a regression on armeb-linux-gnueabihf yroux at gcc dot gnu.org
2015-08-12 13:28 ` [Bug target/67127] " yroux at gcc dot gnu.org
@ 2015-08-17 11:27 ` yroux at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: yroux at gcc dot gnu.org @ 2015-08-17 11:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67127
Yvan Roux <yroux at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
--- Comment #3 from Yvan Roux <yroux at gcc dot gnu.org> ---
Now fixed on trunk and gcc-5 branch.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-08-05 13:23 [Bug target/67127] New: [ARM] Avoiding odd-number ldrd/strd in movdi introduced a regression on armeb-linux-gnueabihf yroux at gcc dot gnu.org
2015-08-12 13:28 ` [Bug target/67127] " yroux at gcc dot gnu.org
2015-08-17 11:27 ` yroux at gcc dot gnu.org
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