linux-kernel - [RFC PATCH v6 10/32] x86/apic: Change apic_*

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Message-ID: <20250514071803.209166-11-Neeraj.Upadhyay@amd.com>
Date: Wed, 14 May 2025 12:47:41 +0530
From: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
To: <linux-kernel@...r.kernel.org>
CC: <bp@...en8.de>, <tglx@...utronix.de>, <mingo@...hat.com>,
	<dave.hansen@...ux.intel.com>, <Thomas.Lendacky@....com>, <nikunj@....com>,
	<Santosh.Shukla@....com>, <Vasant.Hegde@....com>,
	<Suravee.Suthikulpanit@....com>, <David.Kaplan@....com>, <x86@...nel.org>,
	<hpa@...or.com>, <peterz@...radead.org>, <seanjc@...gle.com>,
	<pbonzini@...hat.com>, <kvm@...r.kernel.org>,
	<kirill.shutemov@...ux.intel.com>, <huibo.wang@....com>,
	<naveen.rao@....com>, <francescolavra.fl@...il.com>, <tiala@...rosoft.com>
Subject: [RFC PATCH v6 10/32] x86/apic: Change apic_*_vector() vector param to unsigned

Change vector parameter of apic_{set|clear|test}_vector to
unsigned int to optimize code generation for modulo operation.

On gcc-14.2, code generation for below C statement is given
after it.

long nr = APIC_VECTOR_TO_BIT_NUMBER(vec);

* Without change:

 mov    eax,edi
 sar    eax,0x1f
 shr    eax,0x1b
 add    edi,eax
 and    edi,0x1f
 sub    edi,eax
 movsxd rdi,edi
 mov    QWORD PTR [rsp-0x8],rdi

* With change:

 and    edi,0x1f
 mov    QWORD PTR [rsp-0x8],rdi

Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@....com>
---
Changes since v5:

 - New change.

 arch/x86/include/asm/apic.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 1f9cfb5eb54e..2acf695ed1b7 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -547,17 +547,17 @@ static __always_inline void apic_set_reg64(char *regs, int reg, u64 val)
 	*((u64 *) (regs + reg)) = val;
 }
 
-static inline void apic_clear_vector(int vec, void *bitmap)
+static inline void apic_clear_vector(unsigned int vec, void *bitmap)
 {
 	clear_bit(APIC_VECTOR_TO_BIT_NUMBER(vec), bitmap + APIC_VECTOR_TO_REG_OFFSET(vec));
 }
 
-static inline void apic_set_vector(int vec, void *bitmap)
+static inline void apic_set_vector(unsigned int vec, void *bitmap)
 {
 	set_bit(APIC_VECTOR_TO_BIT_NUMBER(vec), bitmap + APIC_VECTOR_TO_REG_OFFSET(vec));
 }
 
-static inline int apic_test_vector(int vec, void *bitmap)
+static inline int apic_test_vector(unsigned int vec, void *bitmap)
 {
 	return test_bit(APIC_VECTOR_TO_BIT_NUMBER(vec), bitmap + APIC_VECTOR_TO_REG_OFFSET(vec));
 }
-- 
2.34.1