AVX
avx-type-14 exception class
CMPccXADD, which compares a value in memory and adds to it in one atomic step, the class that Intel's manual calls Exceptions Type 14.
- Class
avx-type-14in Intel XED- Applies to
- The VEX encodings of CMPccXADD, which exist only in 64-bit mode.
- Instructions
- 1 mnemonic, 2 forms
- Data
- Intel XED v2026.08.23
Exception conditions
| Exception | Real | Virtual-8086 | Protected | 64-bit | Condition |
|---|---|---|---|---|---|
#UD | yes | yes | yes | no | Always: the instruction exists only in 64-bit mode. |
#UD | no | no | no | yes | A LOCK, REX, F2, F3 or 66 prefix comes before the VEX prefix. |
#UD | no | no | no | yes | The processor lacks the instruction’s extension: its CPUID feature flag is 0. |
#UD | no | no | no | yes | The ModR/M byte encodes a register instead of the memory operand (mod is 11b). |
#SS(0) | no | no | no | yes | A memory operand addressed through SS has a non-canonical address. |
#GP(0) | no | no | no | yes | A memory operand has a non-canonical address. |
#PF(fault-code) | no | no | no | yes | Accessing a memory operand causes a page fault. |
#AC(0) | no | yes | yes | yes | Code at privilege level 3 accesses a misaligned memory operand while alignment checking is on. |
Notes
The memory operand is always locked, so an explicit LOCK prefix is not allowed. The #UD for a register operand comes from the instruction’s page. The manual’s table marks #AC(0) for virtual-8086 and protected mode as well, where the instruction itself raises #UD.
Instructions
Intel XED puts forms of 1 mnemonic in this class, listed here by extension. Where a mnemonic also has forms of other classes, its link leads to its first form of this one.
CMPccXADD
Sources
- Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 2 (325383-093, September 2026): Section 2.6.2, Tables 2-30 and 2-31; Chapter 3, CMPccXADD.
- Intel XED v2026.08.23 (commit
0bcb6237345c): the exception class of each instruction form.
The list of instructions is derived from Intel XED, Copyright Intel Corporation, licensed under the Apache License 2.0; x86-64.net converted and reformatted it. The text is our own.