Improve function doc comments

core/ir/instr.h

@@ -678,6 +678,12 @@ bool
 opc_is_not_a_real_memory_load(int opc);
 
 #if defined(X86) || defined(AARCH64)
+/* Compute the index-th address for a memory operand that uses a vector register for the
+ * base or index register.
+ * The return value has the same semantics as instr_compute_address_ex(). It returns:
+ *   true if index is in bounds and an address was calculated and returned,
+ *   false if index >= the number of addresses this instruction accesses.
+ */
 bool
 instr_compute_vector_address(instr_t *instr, priv_mcontext_t *mc, size_t mc_size,
                              dr_mcontext_flags_t mc_flags, opnd_t curop, uint index,

core/ir/instr_api.h

@@ -1639,7 +1639,8 @@ DR_API
  * write is returned in \p is_write.  Either or both OUT variables can
  * be NULL.
  * \p mc->flags must include DR_MC_CONTROL and DR_MC_INTEGER.
- * For instructions that use vector addressing (VSIB, introduced in AVX2),
+ * For instructions that use vector addressing (x86 VSIB, introduced in AVX2, or
+ * AArch64 scatter/gather instructions introduced in SVE/SVE2),
  * mc->flags must additionally include DR_MC_MULTIMEDIA.
  *
  * Like instr_reads_memory(), this routine does not consider