Rmo Description in Mur'

(d2) calls Dep Reg() which returns true if the preceding instruction is writing the same register that is read by the following instruction (strictly speaking, the same temporary location in register renaming scheme). Note that the dependence through the condition code register is checked separately, since branch instructions read the condition code register which is modified by such instructions as test or compare. The third Boolean expression directly translates the rule (d3). Rule "Execute one of the instructions in minimal set" & mAddress(p,j) = mAddress(p,i)) EndForall) ==> Begin-The chosen instruction[p][i]-is allowed to be performed. Figure 7: RMO ordering constraints rule in Mur'. The main rule for the memory order constraints is in figure 7. This rule can also be thought of as implementing the behavior of the memory. The rule is embedded in parameterized rulesets that nondeterministically choose a reorder box and an instruction index. It performs the instruction at that reorder box index only if that instruction is allowed to appear first among all the instructions in the ordering box, according to the memory ordering rules. The condition of the rule is a conjunction of several Boolean expressions. The first Boolean condition ensures that the chosen index of the reorder box is not an empty slot. The second condition requires every membar instruction to remain in the reorder box until all the previous instructions are executed and removed from the box. The rest of the three Boolean expressions correspond to < m ordering rules (m1), (m2), and (m3), respectively. Note that the predicate L(X) in the rule (m1) is replaced by the function checking if the instruction is writing to a register, because reorder boxes deal with all kinds of instructions as well as memory transactions, while the axioms in the previous section are aimed to enforce orders among memory transactions only. The conditions are not direct translation of the rules, but they ensure that there is no preceding transaction which is <m ordered to the one at entry i. If the condition is true, then the chosen instruction is performed calling the corresponding procedure (e.g., Read() for a load and Ldstore perf() for a load-store) according to the instruction type, and removed from the reorder box. Several types of errors can be detected in a Mur' description. There is an error statement that can appear in an action. Invariant Boolean expressions may also be specified; if the invariant …