RISC-V C.NOP Instruction Details
Instruction ManualCI formatFixed 16-bit no-operation. CI format; adjacent rd=x0, imm!=0 encodings are HINTs.
Instruction Syntax
Instruction Behavior
C.NOP is the fixed CI-format encoding with rd=x0 and imm=0. It changes no user-visible state except advancing pc and incrementing applicable performance counters, and expands to nop. In the shared C.ADDI space, adjacent rd=x0, imm!=0 encodings are HINTs, not C.NOP.
C.NOP Decode And Execute Animation
Decodes the real 16-bit CR or CI encoding and distinguishes normal instructions, HINTs, and shared encodings.
Step 1: identify the fixed C.NOP encoding
The animation shows C-extension 16-bit fields directly instead of pretending this is a 32-bit scalar instruction.
0x0001 = 0000000000000001C.NOP changes no user-visible state except advancing pc and incrementing applicable performance counters.
This animation shows only officially defined decode, register reads, arithmetic, and architectural state, not a particular implementation's pipeline, cache, prediction, or timing.
Common Usage Scenarios
Understand this scenario with real code like «c.nop # 16-bit no-operation».
Understand this scenario with real code like «c.nop # 16-bit no-operation».
Pre-Use Checklist
- Confirm the current instruction format is CI format.
- Confirm the operand order matches the example.
- Ensure the destination register usage is compatible with the calling convention.
- Confirm this is not the lower-level form of a pseudo-instruction expansion.