LZCNT (R64, R64)

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: w, 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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
• Documentation
• Latency: 3.0
• Throughput: 1.0

Cascade Lake

• Measurements
• Latencies
  • Latency operand 1 → 1: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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: 0
  • Latency operand 1 → 3: 0
  • 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 2.2
• 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 2.2
• 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 2.2
• 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 2.2
• 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: 11
  • Latency operand 2 → 3: 9
• 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): 16.00
  • 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: 0
  • Latency operand 1 → 3: 0
  • Latency operand 2 → 1: 1
  • Latency operand 2 → 3: 1
• Throughput
  • Measured (loop): 0.25
  • Measured (unrolled): 0.30
• Number of μops
  • Executed: 1

AMD Zen 3

• Measurements
• Latencies
  • Latency operand 1 → 1: 0
  • Latency operand 1 → 3: 0
  • Latency operand 2 → 1: 1
  • Latency operand 2 → 3: 1
• Throughput
  • Measured (loop): 0.25
  • Measured (unrolled): 0.31
• Number of μops
  • Executed: 1
• Documentation
• Latency: 1
• Throughput: 0.25
• Number of μops: 1
• Port usage: ALU

AMD Zen 2

• Measurements
• Latencies
  • Latency operand 1 → 1: 0
  • Latency operand 1 → 3: 0
  • Latency operand 2 → 1: 1
  • Latency operand 2 → 3: 1
• Throughput
  • Measured (loop): 0.33
  • Measured (unrolled): 0.31
• Number of μops
  • Executed: 1
• Documentation
• Latency: 1
• Throughput: 0.25
• Number of μops: 1
• Port usage: ALU

AMD Zen+

• Measurements
• Latencies
  • Latency operand 1 → 1: 0
  • Latency operand 1 → 3: 0
  • Latency operand 2 → 1: 1
  • Latency operand 2 → 3: 1
• Throughput
  • Measured (loop): 0.40
  • Measured (unrolled): 0.31
• Number of μops
  • Executed: 1
• Documentation
• Latency: 1
• Throughput: 0.25
• Number of μops: 1
• Port usage: ALU