[arch-commits] Commit in rkt/trunk (ilog2.patch)

Massimiliano Torromeo mtorromeo at archlinux.org
Sat Oct 7 14:57:17 UTC 2017


    Date: Saturday, October 7, 2017 @ 14:57:16
  Author: mtorromeo
Revision: 262078

upgpkg: rkt 1.29.0-1

Deleted:
  rkt/trunk/ilog2.patch

-------------+
 ilog2.patch |  126 ----------------------------------------------------------
 1 file changed, 126 deletions(-)

Deleted: ilog2.patch
===================================================================
--- ilog2.patch	2017-10-07 14:56:41 UTC (rev 262077)
+++ ilog2.patch	2017-10-07 14:57:16 UTC (rev 262078)
@@ -1,126 +0,0 @@
-From 474c90156c8dcc2fa815e6716cc9394d7930cb9c Mon Sep 17 00:00:00 2001
-From: Linus Torvalds <torvalds at linux-foundation.org>
-Date: Thu, 2 Mar 2017 12:17:22 -0800
-Subject: give up on gcc ilog2() constant optimizations
-
-gcc-7 has an "optimization" pass that completely screws up, and
-generates the code expansion for the (impossible) case of calling
-ilog2() with a zero constant, even when the code gcc compiles does not
-actually have a zero constant.
-
-And we try to generate a compile-time error for anybody doing ilog2() on
-a constant where that doesn't make sense (be it zero or negative).  So
-now gcc7 will fail the build due to our sanity checking, because it
-created that constant-zero case that didn't actually exist in the source
-code.
-
-There's a whole long discussion on the kernel mailing about how to work
-around this gcc bug.  The gcc people themselevs have discussed their
-"feature" in
-
-   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72785
-
-but it's all water under the bridge, because while it looked at one
-point like it would be solved by the time gcc7 was released, that was
-not to be.
-
-So now we have to deal with this compiler braindamage.
-
-And the only simple approach seems to be to just delete the code that
-tries to warn about bad uses of ilog2().
-
-So now "ilog2()" will just return 0 not just for the value 1, but for
-any non-positive value too.
-
-It's not like I can recall anybody having ever actually tried to use
-this function on any invalid value, but maybe the sanity check just
-meant that such code never made it out in public.
-
-Reported-by: Laura Abbott <labbott at redhat.com>
-Cc: John Stultz <john.stultz at linaro.org>,
-Cc: Thomas Gleixner <tglx at linutronix.de>
-Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
-Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
----
- include/linux/log2.h       | 13 ++-----------
- tools/include/linux/log2.h | 13 ++-----------
- 2 files changed, 4 insertions(+), 22 deletions(-)
-
-diff --git a/include/linux/log2.h b/include/linux/log2.h
-index ef3d4f6..c373295 100644
---- a/include/linux/log2.h
-+++ b/include/linux/log2.h
-@@ -16,12 +16,6 @@
- #include <linux/bitops.h>
- 
- /*
-- * deal with unrepresentable constant logarithms
-- */
--extern __attribute__((const, noreturn))
--int ____ilog2_NaN(void);
--
--/*
-  * non-constant log of base 2 calculators
-  * - the arch may override these in asm/bitops.h if they can be implemented
-  *   more efficiently than using fls() and fls64()
-@@ -85,7 +79,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
- #define ilog2(n)				\
- (						\
- 	__builtin_constant_p(n) ? (		\
--		(n) < 1 ? ____ilog2_NaN() :	\
-+		(n) < 2 ? 0 :			\
- 		(n) & (1ULL << 63) ? 63 :	\
- 		(n) & (1ULL << 62) ? 62 :	\
- 		(n) & (1ULL << 61) ? 61 :	\
-@@ -148,10 +142,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
- 		(n) & (1ULL <<  4) ?  4 :	\
- 		(n) & (1ULL <<  3) ?  3 :	\
- 		(n) & (1ULL <<  2) ?  2 :	\
--		(n) & (1ULL <<  1) ?  1 :	\
--		(n) & (1ULL <<  0) ?  0 :	\
--		____ilog2_NaN()			\
--				   ) :		\
-+		1 ) :				\
- 	(sizeof(n) <= 4) ?			\
- 	__ilog2_u32(n) :			\
- 	__ilog2_u64(n)				\
-diff --git a/tools/include/linux/log2.h b/tools/include/linux/log2.h
-index 4144666..d5677d3 100644
---- a/tools/include/linux/log2.h
-+++ b/tools/include/linux/log2.h
-@@ -13,12 +13,6 @@
- #define _TOOLS_LINUX_LOG2_H
- 
- /*
-- * deal with unrepresentable constant logarithms
-- */
--extern __attribute__((const, noreturn))
--int ____ilog2_NaN(void);
--
--/*
-  * non-constant log of base 2 calculators
-  * - the arch may override these in asm/bitops.h if they can be implemented
-  *   more efficiently than using fls() and fls64()
-@@ -78,7 +72,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
- #define ilog2(n)				\
- (						\
- 	__builtin_constant_p(n) ? (		\
--		(n) < 1 ? ____ilog2_NaN() :	\
-+		(n) < 2 ? 0 :			\
- 		(n) & (1ULL << 63) ? 63 :	\
- 		(n) & (1ULL << 62) ? 62 :	\
- 		(n) & (1ULL << 61) ? 61 :	\
-@@ -141,10 +135,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
- 		(n) & (1ULL <<  4) ?  4 :	\
- 		(n) & (1ULL <<  3) ?  3 :	\
- 		(n) & (1ULL <<  2) ?  2 :	\
--		(n) & (1ULL <<  1) ?  1 :	\
--		(n) & (1ULL <<  0) ?  0 :	\
--		____ilog2_NaN()			\
--				   ) :		\
-+		1 ) :				\
- 	(sizeof(n) <= 4) ?			\
- 	__ilog2_u32(n) :			\
- 	__ilog2_u64(n)				\
--- 
-cgit v1.1



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