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* [PATCH 00/10] x86: use gcc 6+ asm flag output feature
@ 2016-06-07 23:30 H. Peter Anvin
  2016-06-07 23:31 ` [PATCH 01/10] x86, bitops: remove use of "sbb" to return CF H. Peter Anvin
                   ` (11 more replies)
  0 siblings, 12 replies; 42+ messages in thread
From: H. Peter Anvin @ 2016-06-07 23:30 UTC (permalink / raw)
  To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Linux Kernel Mailing List
  Cc: Peter Zijlstra, Andy Lutomirski, Borislav Petkov

From: "H. Peter Anvin" <hpa@zytor.com>

gcc 6+ has the ability to let flags (actually, conditions, which are
specific combinations of flags) to be used directly as asm() outputs.
The syntax for that is "=@cc<cc>" where <cc> is the same set of
letters that would be used in a j<cc> or set<cc> instruction
(e.g. "=@ccz" to test the ZF flag.)

This patchset by itself reduces the size of the x86-64 kernel by
0.12%, from a baseline of 4.7-rc2 built with gcc 6.1 (first line is
with the patchset, the second one is without):

     text       data       bss        dec       hex filename
     
 68245656   41004339  20533248  129783243   7bc55cb o.i386-allconfig/vmlinux
 68355716   41008499  20533248  129897463   7be13f7 o.i386-allconfig/vmlinux

127384005  129742359  38150144  295276508  11998fdc o.x86_64-allconfig/vmlinux
127538765  129742295  38150144  295431204  119bec24 o.x86_64-allconfig/vmlinux

^ permalink raw reply	[flat|nested] 42+ messages in thread

end of thread, other threads:[~2016-06-08 19:35 UTC | newest]

Thread overview: 42+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-06-07 23:30 [PATCH 00/10] x86: use gcc 6+ asm flag output feature H. Peter Anvin
2016-06-07 23:31 ` [PATCH 01/10] x86, bitops: remove use of "sbb" to return CF H. Peter Anvin
2016-06-07 23:39   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 02/10] x86, asm: use bool for bitops and other assembly outputs H. Peter Anvin
2016-06-07 23:40   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08  7:49   ` [PATCH 02/10] " Peter Zijlstra
2016-06-08  8:28     ` Ingo Molnar
2016-06-08  8:33       ` Ingo Molnar
2016-06-08  8:55         ` H. Peter Anvin
2016-06-08  9:01           ` Ingo Molnar
2016-06-08  9:12             ` H. Peter Anvin
2016-06-08  9:20               ` Ingo Molnar
2016-06-08  9:31                 ` H. Peter Anvin
2016-06-08  9:39                   ` Peter Zijlstra
2016-06-08  9:43                     ` H. Peter Anvin
2016-06-08  9:40                 ` H. Peter Anvin
2016-06-08  8:58       ` H. Peter Anvin
2016-06-08  9:06         ` Ingo Molnar
2016-06-07 23:31 ` [PATCH 03/10] x86, asm: change the GEN_*_RMWcc() macros to not quote the condition H. Peter Anvin
2016-06-07 23:40   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 04/10] x86, asm: define CC_SET() and CC_OUT() macros H. Peter Anvin
2016-06-07 23:40   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08  5:09   ` [PATCH 04/10] " Andy Lutomirski
2016-06-08 19:29     ` H. Peter Anvin
2016-06-08 19:34       ` H. Peter Anvin
2016-06-08 19:35         ` Borislav Petkov
2016-06-07 23:31 ` [PATCH 05/10] x86, asm: change GEN_*_RMWcc() to use CC_SET()/CC_OUT() H. Peter Anvin
2016-06-07 23:41   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 06/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/bitops.h> H. Peter Anvin
2016-06-07 23:41   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 07/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/percpu.h> H. Peter Anvin
2016-06-07 23:42   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 08/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/rwsem.h> H. Peter Anvin
2016-06-07 23:42   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-07 23:31 ` [PATCH 09/10] x86, asm: Use CC_SET()/CC_OUT() and static_cpu_has() in archrandom.h H. Peter Anvin
2016-06-07 23:42   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08  5:12   ` [PATCH 09/10] " Andy Lutomirski
2016-06-07 23:31 ` [PATCH 10/10] x86, asm, boot: Use CC_SET()/CC_OUT() in arch/x86/boot/boot.h H. Peter Anvin
2016-06-07 23:43   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08  8:00 ` [PATCH 00/10] x86: use gcc 6+ asm flag output feature Peter Zijlstra
2016-06-08  8:56   ` H. Peter Anvin
2016-06-08  8:26 ` Ingo Molnar

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