50 lines
2.0 KiB
Diff
50 lines
2.0 KiB
Diff
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From d69db2ba3ce47f6eded0a8843c413a67d26e6375 Mon Sep 17 00:00:00 2001
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From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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Date: Sun, 24 Jul 2022 20:37:51 +0200
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Subject: [PATCH] src/corelib/global/qsimd_p.h: fix build on ARM < v7 due to
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yield instruction
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On ARM < v7 with gcc, the build fails with:
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/tmp/ccRlrCQi.s: Assembler messages:
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/tmp/ccRlrCQi.s:3858: Error: selected processor does not support `yield' in ARM mode
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/tmp/ccRlrCQi.s:3875: Error: selected processor does not support `yield' in ARM mode
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/tmp/ccRlrCQi.s:4606: Error: selected processor does not support `yield' in ARM mode
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/tmp/ccRlrCQi.s:4853: Error: selected processor does not support `yield' in ARM mode
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/tmp/ccRlrCQi.s:5268: Error: selected processor does not support `yield' in ARM mode
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while building src/corelib/thread/qfutureinterface.cpp.
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This is due to the fact that the qYieldCpu() macro on ARM, assumes
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that if the compiler is gcc, we can do asm volatile("yield"). However,
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this instruction is only guaranteed to exist on ARMv7+ cores. It
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doesn't exist on ARMv5, and only some (but not all) ARMv6 cores have
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it. If it's not available, we just fallback to the default behavior of
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qYieldCpu(), which is to do nothing.
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Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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Upstream bug: https://bugreports.qt.io/browse/QTBUG-105162
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---
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src/corelib/global/qsimd_p.h | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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diff --git a/src/corelib/global/qsimd_p.h b/src/corelib/global/qsimd_p.h
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index d270d09f2f..b84b257e54 100644
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--- a/src/corelib/global/qsimd_p.h
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+++ b/src/corelib/global/qsimd_p.h
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@@ -428,7 +428,10 @@ static inline void qYieldCpu()
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https://stackoverflow.com/a/70076751/134841
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105416
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*/
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- asm volatile("yield"); /* this works everywhere */
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+# if defined(Q_PROCESSOR_ARM_V7)
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+ /* The yield instruction appeared in ARMv7 */
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+ asm volatile("yield");
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+# endif
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# else
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__yield(); /* this is what should work everywhere */
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# endif
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--
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2.37.1
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