[PATCH 02/17] x86, lto: Disable fancy hweight optimizations for LTO v2

[Andi Kleen <ak@linux.intel.com>]

The fancy x86 hweight uses different compiler options for the
hweight file. This does not work with LTO. Just disable the optimization
with LTO

v2: Simplify Kconfig checks (Jan Beulich)
Cc: x86@kernel.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/Kconfig                    | 1 +
 arch/x86/include/asm/arch_hweight.h | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 940e50e..f125c5f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -255,6 +255,7 @@ config X86_32_LAZY_GS
 
 config ARCH_HWEIGHT_CFLAGS
 	string
+	default "" if LTO
 	default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
 	default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
 
diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h
index 9686c3d..ca80549 100644
--- a/arch/x86/include/asm/arch_hweight.h
+++ b/arch/x86/include/asm/arch_hweight.h
@@ -25,9 +25,14 @@ static inline unsigned int __arch_hweight32(unsigned int w)
 {
 	unsigned int res = 0;
 
+#ifdef CONFIG_LTO
+	res  = __sw_hweight32(w);
+#else
+
 	asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT)
 		     : "="REG_OUT (res)
 		     : REG_IN (w));
+#endif
 
 	return res;
 }
@@ -46,6 +51,9 @@ static inline unsigned long __arch_hweight64(__u64 w)
 {
 	unsigned long res = 0;
 
+#ifdef CONFIG_LTO
+	res = __sw_hweight64(w);
+#else
 #ifdef CONFIG_X86_32
 	return  __arch_hweight32((u32)w) +
 		__arch_hweight32((u32)(w >> 32));
@@ -54,6 +62,7 @@ static inline unsigned long __arch_hweight64(__u64 w)
 		     : "="REG_OUT (res)
 		     : REG_IN (w));
 #endif /* CONFIG_X86_32 */
+#endif
 
 	return res;
 }
-- 
1.8.5.2