Does cpopw access memory?
No. It reads integer register operands and writes rd only.
CPOPW
RISC-V CPOPW Instruction Details
Instruction ManualR-typeCount set bits in word (RV64)
Instruction Syntax
cpopw rd, rs1
Operand Breakdown
Destination rd: register receiving the operation result.
Source rs1: register holding the first operand.
Source rs2: register holding the second operand.
BZbbBit Manipulation
Related Search Terms
Instruction Behavior
cpopw on RV64 counts one bits only in the low 32 bits of rs1.
Quick Understanding & Search Notes
cpopw on RV64 counts one bits only in the low 32 bits of rs1.
These instructions are part of a B-extension subset and operate on XLEN-wide integer register values.
The result range is 0..32; upper bits do not participate.
Common Usage Scenarios
Bit Operations & Masks
Understand this scenario with real code like «cpopw x10, x11 ; x10 = number of 1-bits in x11[31:0]».
Debug & Monitoring
Understand this scenario with real code like «cpopw x10, x11 ; x10 = number of 1-bits in x11[31:0]».
Pre-Use Checklist
Syntax Check
- Confirm the current instruction format is R-type.
- Confirm the operand order matches the example.
Semantic Check
- Ensure the destination register usage is compatible with the calling convention.
- Confirm this is not the lower-level form of a pseudo-instruction expansion.
Pitfalls / Common Confusions
The result range is 0..32; upper bits do not participate.
FAQ
Does cpopw interpret signed numbers?
These bit operations work on bit patterns directly; aside from the specified word-width selection, arithmetic signed magnitude is not used.