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ARM: div64: improve __arch_xprod_64()

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Let's use the same criteria for overflow handling necessity as the
generic code.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Nicolas Pitre 2024-10-03 17:16:15 -04:00 committed by Arnd Bergmann
parent 00a31dd3ac
commit 06508533d5
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GPG Key ID: 60AB47FFC9095227
1 changed files with 4 additions and 2 deletions
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6
arch/arm/include/asm/div64.h
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@ -56,6 +56,8 @@ static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias)
{
unsigned long long res;
register unsigned int tmp asm("ip") = 0;
bool no_ovf = __builtin_constant_p(m) &&
((m >> 32) + (m & 0xffffffff) < 0x100000000);
if (!bias) {
asm ( "umull %Q0, %R0, %Q1, %Q2\n\t"
@ -63,7 +65,7 @@ static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias)
: "=&r" (res)
: "r" (m), "r" (n)
: "cc");
} else if (!(m & ((1ULL << 63) | (1ULL << 31)))) {
} else if (no_ovf) {
res = m;
asm ( "umlal %Q0, %R0, %Q1, %Q2\n\t"
"mov %Q0, #0"
@ -80,7 +82,7 @@ static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias)
: "cc");
}
if (!(m & ((1ULL << 63) | (1ULL << 31)))) {
if (no_ovf) {
asm ( "umlal %R0, %Q0, %R1, %Q2\n\t"
"umlal %R0, %Q0, %Q1, %R2\n\t"
"mov %R0, #0\n\t"