linux-kernel - [PATCH 03/13] ARM: div64: fix building with gcc-4.5 and lower

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Date:   Fri, 16 Dec 2016 11:56:24 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-arch@...r.kernel.org
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...r.kernel.org,
        Russell King <rmk+kernel@...linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kernel-build-reports@...ts.linaro.org,
        kvmarm@...ts.cs.columbia.edu, Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 03/13] ARM: div64: fix building with gcc-4.5 and lower

drivers/media/dvb-frontends/s921.c: In function 's921_pll_tune':
arch/arm/include/asm/div64.h:109: error: can't find a register in class 'GENERAL_REGS' while reloading 'asm'
arch/arm/include/asm/div64.h:127: error: can't find a register in class 'GENERAL_REGS' while reloading 'asm'
arch/arm/include/asm/div64.h:109: error: 'asm' operand has impossible constraints
arch/arm/include/asm/div64.h:127: error: 'asm' operand has impossible constraints
scripts/Makefile.build:299: recipe for target 'drivers/media/dvb-frontends/s921.o' failed

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/arm/include/asm/div64.h | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
index 7ca0c613c33b..e1c8d4a58797 100644
--- a/arch/arm/include/asm/div64.h
+++ b/arch/arm/include/asm/div64.h
@@ -66,27 +66,16 @@ static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
  */
 #define do_div(n, base) __div64_32(&(n), base)
 
-#elif defined(CONFIG_CPU_32v3)
+#elif GCC_VERSION < 40600
 
 /*
- * modern compiler versions (>= gcc-4.9) tend to misoptimize
- * the code for ARMv3, and this is not getting fixed any more.
+ * gcc-4.4 and gcc-4.5 tend to run out of registers in their
+ * register allocation in some functions
  */
 #define do_div(n, base) __div64_32(&(n), base)
 
 #else
 
-/*
- * gcc versions earlier than 4.0 are simply too problematic for the
- * __div64_const32() code in asm-generic/div64.h. First there is
- * gcc PR 15089 that tend to trig on more complex constructs, spurious
- * .global __udivsi3 are inserted even if none of those symbols are
- * referenced in the generated code, and those gcc versions are not able
- * to do constant propagation on long long values anyway.
- */
-
-#define __div64_const32_is_OK (__GNUC__ >= 4)
-
 static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias)
 {
 	unsigned long long res;
-- 
2.9.0