Is czero.nez a conditional branch?
No. It does not change the PC; it selects zero or rs1 based on whether rs2 is zero.
CZERO.NEZ
RISC-V CZERO.NEZ Instruction Details
Instruction ManualR-typeConditional zero: if rs2 != 0 then rd=0, else rd=rs1
Instruction Syntax
czero.nez rd, rs1, rs2
Operand Breakdown
Destination rd: register receiving the operation result.
Source rs1: register holding the first operand.
Source rs2: register holding the second operand.
ZicondConditional Operations
Instruction Behavior
czero.nez is a Zicond conditional-zero instruction. If rs2 is not equal to zero, rd is written with zero; otherwise rd is written with rs1.
Quick Understanding & Search Notes
czero.nez is a Zicond conditional-zero instruction. If rs2 is not equal to zero, rd is written with zero; otherwise rd is written with rs1.
It can be used to build branchless conditional-select sequences, but architecturally it only conditionally writes zero.
rd has syntactic dependencies on both rs1 and rs2, as defined by the official manual.
Common Usage Scenarios
Branch & Jump
Understand this scenario with real code like «czero.nez x10, x11, x12 ; x10 = (x12 != 0) ? 0 : x11».
Register Operations
Understand this scenario with real code like «czero.nez x10, x11, x12 ; x10 = (x12 != 0) ? 0 : x11».
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
It selects only between zero and rs1; it does not branch and does not access memory.
The condition tests whether rs2 is zero; it does not compare rs1 with rs2.
FAQ
Does czero.nez compare two register magnitudes?
No. The condition only tests whether rs2 is zero.