BSF (R64, R64)
Summary:
"Bit Scan Forward"
Reference:
https://www.felixcloutier.com/x86/BSF.html
Extension:
BASE
Category:
BITBYTE
ISA-Set:
I386
CPL:
3
iform:
BSF_GPRv_GPRv
iclass:
BSF
ASM:
BSF
Operands
Operand 1 (w): Register (RAX, RCX, RDX, RBX, RSP, RBP, RSI, RDI, R8, R9, R10, R11, R12, R13, R14, R15)
Operand 2 (r): Register (RAX, RCX, RDX, RBX, RSP, RBP, RSI, RDI, R8, R9, R10, R11, R12, R13, R14, R15)
Operand 3 (w, suppressed): Flags (AF: undef, CF: undef, OF: undef, PF: undef, SF: undef, ZF: w)
Available performance data
Alder Lake-P
Alder Lake-E
Rocket Lake
Tiger Lake
Ice Lake
Cascade Lake
Cannon Lake
Skylake-X
Coffee Lake
Kaby Lake
Skylake
Broadwell
Haswell
Ivy Bridge
Sandy Bridge
Westmere
Nehalem
Wolfdale
Conroe
Tremont
Goldmont Plus
Goldmont
Airmont
Bonnell
AMD Zen 4
AMD Zen 3
AMD Zen 2
AMD Zen+
Alder Lake-P
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Alder Lake-E
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Microcode Sequencer (MS): 0
Rocket Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Tiger Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Ice Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Cascade Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Cannon Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Skylake-X
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.3
Throughput
Computed from the port usage: 1.00
IACA:
1.00
Number of μops:
1
Port usage:
1*p1
IACA 3.0
Throughput
Computed from the port usage: 1.00
IACA:
0.98
Number of μops:
1
Port usage:
1*p1
Coffee Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Kaby Lake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
Skylake
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.3
Throughput
Computed from the port usage: 1.00
IACA:
1.00
Number of μops:
1
Port usage:
1*p1
IACA 3.0
Throughput
Computed from the port usage: 1.00
IACA:
0.98
Number of μops:
1
Port usage:
1*p1
Broadwell
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.2
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.3
Throughput
Computed from the port usage: 1.00
IACA:
1.00
Number of μops:
1
Port usage:
1*p1
IACA 3.0
Throughput
Computed from the port usage: 1.00
IACA:
0.98
Number of μops:
1
Port usage:
1*p1
Haswell
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.1
Latency:
3
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.2
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.3
Throughput
Computed from the port usage: 1.00
IACA:
1.00
Number of μops:
1
Port usage:
1*p1
IACA 3.0
Throughput
Computed from the port usage: 1.00
IACA:
0.98
Number of μops:
1
Port usage:
1*p1
Ivy Bridge
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.1
Latency:
3
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.2
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.3
Throughput
Computed from the port usage: 1.00
IACA:
1.00
Number of μops:
1
Port usage:
1*p1
Sandy Bridge
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Decoded (MITE): 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.1
Latency:
3
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.2
Throughput
Computed from the port usage: 1.00
IACA:
1.00 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.3
Throughput
Computed from the port usage: 1.00
IACA:
1.00
Number of μops:
1
Port usage:
1*p1
Westmere
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.1
Latency:
3
Throughput
Computed from the port usage: 1.00
IACA:
1.50 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.2
Throughput
Computed from the port usage: 1.00
IACA:
1.50 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
Nehalem
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Retire slots: 1
Microcode Sequencer (MS): 0
Port usage:
1*p1
IACA 2.1
Latency:
3
Throughput
Computed from the port usage: 1.00
IACA:
1.50 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
IACA 2.2
Throughput
Computed from the port usage: 1.00
IACA:
1.50 (with the -no_interiteration flag: 1.00)
Number of μops:
1
Port usage:
1*p1
Wolfdale
Measurements
Latencies
Latency operand 1 → 1:
1
Latency operand 1 → 3:
0
Latency operand 2 → 1:
2
Latency operand 2 → 3:
2
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 2
Port usage:
1*p015+1*p1
Conroe
Measurements
Latencies
Latency operand 1 → 1:
1
Latency operand 1 → 3:
0
Latency operand 2 → 1:
2
Latency operand 2 → 3:
2
Throughput
Computed from the port usage: 1.00
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 2
Port usage:
1*p015+1*p1
Tremont
Measurements
Latencies
Latency operand 1 → 1:
3
Latency operand 1 → 3:
3
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Measured (loop):
1.00
Measured (unrolled):
1.00
Number of μops
Executed: 1
Microcode Sequencer (MS): 0
Goldmont Plus
Measurements
Latencies
Latency operand 1 → 1:
8
Latency operand 1 → 3:
7
Latency operand 2 → 1:
10
Latency operand 2 → 3:
9
Throughput
Measured (loop):
8.00
Measured (unrolled):
8.00
Number of μops
Executed: 11
Microcode Sequencer (MS): 11
Requires the complex decoder
Goldmont
Measurements
Latencies
Latency operand 1 → 1:
8
Latency operand 1 → 3:
7
Latency operand 2 → 1:
11
Latency operand 2 → 3:
10
Throughput
Measured (loop):
8.00
Measured (unrolled):
8.00
Number of μops
Executed: 11
Microcode Sequencer (MS): 11
Requires the complex decoder
Airmont
Measurements
Latencies
Latency operand 1 → 1:
7
Latency operand 1 → 3:
6
Latency operand 2 → 1:
10
Latency operand 2 → 3:
8
Throughput
Measured (loop):
10.00
Measured (unrolled):
10.00
Number of μops
Executed: 10
Microcode Sequencer (MS): 10
Requires the complex decoder
Bonnell
Measurements
Latencies
Latency operand 1 → 1:
16
Latency operand 1 → 3:
16
Latency operand 2 → 1:
17
Latency operand 2 → 3:
17
Throughput
Measured (loop):
16.02
Measured (unrolled):
16.00
Number of μops
Executed: 10
Microcode Sequencer (MS): 10
Requires the complex decoder
AMD Zen 4
Measurements
Latencies
Latency operand 1 → 1:
1
Latency operand 1 → 3:
1
Latency operand 2 → 1:
1
Latency operand 2 → 3:
1
Throughput
Measured (loop):
0.25
Measured (unrolled):
0.25
Number of μops
Executed: 1
AMD Zen 3
Measurements
Latencies
Latency operand 1 → 1:
2
Latency operand 1 → 3:
0
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Measured (loop):
3.00
Measured (unrolled):
3.00
Number of μops
Executed: 6
Documentation
Latency: 3
Throughput: 2.00
Number of μops: 6
AMD Zen 2
Measurements
Latencies
Latency operand 1 → 1:
2
Latency operand 1 → 3:
0
Latency operand 2 → 1:
3
Latency operand 2 → 3:
3
Throughput
Measured (loop):
3.00
Measured (unrolled):
3.00
Number of μops
Executed: 6
Documentation
Latency: 3
Throughput: 2.00
Number of μops: 6
AMD Zen+
Measurements
Latencies
Latency operand 1 → 1:
2
Latency operand 1 → 3:
0
Latency operand 2 → 1:
3
Latency operand 2 → 3:
4
Throughput
Measured (loop):
3.00
Measured (unrolled):
3.00
Number of μops
Executed: 6
Documentation
Latency: 3
Throughput: 2.00
Number of μops: 6