api: fix handling of multiple conditions for buffering

devito/ir/clusters/algorithms.py

@@ -259,10 +259,17 @@ def guard(clusters):
             # Separate out the indirect ConditionalDimensions, which only serve
             # the purpose of protecting from OOB accesses
             cds = [d for d in cds if not d.indirect]
+            modes = [cd.relation for cd in cds]
+            if len({m == 'strict' for m in modes}) > 1:
+                raise CompilationError("Only one `strict` condition"
+                                       "can be used in an equation")
+            elif 'strict' in modes:
+                mode = 'strict'
+            else:
+                mode = sympy.And if sympy.And in modes else sympy.Or
 
             # Chain together all `cds` conditions from all expressions in `c`
             guards = {}
-            mode = sympy.Or
             for cd in cds:
                 # `BOTTOM` parent implies a guard that lives outside of
                 # any iteration space, which corresponds to the placeholder None
@@ -279,7 +286,6 @@ def guard(clusters):
 
                 # Pull `cd` from any expr
                 condition = guards.setdefault(k, [])
-                mode = mode and cd.relation
                 for e in exprs:
                     try:
                         condition.append(e.conditionals[cd])
@@ -296,7 +302,10 @@ def guard(clusters):
 
             # Combination `mode` is And by default.
             # If all conditions are Or then Or combination `mode` is used.
-            guards = {d: mode(*v, evaluate=False) for d, v in guards.items()}
+            if mode == 'strict':
+                guards = {d: v[0] for d, v in guards.items()}
+            else:
+                guards = {d: mode(*v, evaluate=False) for d, v in guards.items()}
 
             # Construct a guarded Cluster
             processed.append(c.rebuild(exprs=exprs, guards=guards))

devito/ir/equations/equation.py

@@ -11,7 +11,9 @@
 )
 from devito.symbolics import IntDiv, limits_mapper, uxreplace
 from devito.tools import Pickable, Tag, frozendict
-from devito.types import Eq, Inc, ReduceMax, ReduceMin, ReduceMinMax, relational_min
+from devito.types import (
+    Eq, Inc, ReduceMax, ReduceMin, ReduceMinMax, relational_min, relational_shift
+)
 
 __all__ = [
     'ClusterizedEq',
@@ -222,7 +224,7 @@ def __new__(cls, *args, **kwargs):
                                   relations=ordering.relations, mode='partial')
         ispace = IterationSpace(intervals, iterators)
 
-        # Construct the conditionals and replace the ConditionalDimensions in `expr`
+        # Construct the conditionals
         conditionals = {}
         for d in ordering:
             if not d.is_Conditional:
@@ -234,13 +236,32 @@ def __new__(cls, *args, **kwargs):
                 if d._factor is not None:
                     cond = d.relation(cond, GuardFactor(d))
                 conditionals[d] = cond
+
+        # Merge conditionals when possible. E.g if we have an implicit_dim
+        # and there is a dimension with the same parent, we ca merged
+        # its condition
+        for d in input_expr.implicit_dims:
+            if d not in conditionals:
+                continue
+            for cd in dict(conditionals):
+                if cd.parent == d.parent and cd != d:
+                    cond = conditionals.pop(d)
+                    if d.relation == 'strict':
+                        conditionals[d] = cond
+                        conditionals.pop(cd)
+                    else:
+                        mode = cd.relation and d.relation
+                        conditionals[cd] = mode(cond, conditionals[cd])
+                    break
+
+        # Replace the ConditionalDimensions in `expr`
+        for d, cond in conditionals.items():
             # Replace dimension with index
             index = d.index
             if d.condition is not None and d in expr.free_symbols:
-                index = index - relational_min(d.condition, d.parent)
-            expr = uxreplace(expr, {d: IntDiv(index, d.symbolic_factor)})
-
-        conditionals = frozendict(conditionals)
+                index = index - relational_min(cond, d.parent)
+            shift = relational_shift(cond, d.parent)
+            expr = uxreplace(expr, {d: IntDiv(index, d.symbolic_factor) + shift})
 
         # Lower all Differentiable operations into SymPy operations
         rhs = diff2sympy(expr.rhs)

devito/ir/support/vector.py

@@ -128,6 +128,7 @@ def __lt__(self, other):
                         return True
                     elif q_positive(i):
                         return False
+
                 raise TypeError("Non-comparable index functions") from e
 
         return False
@@ -164,6 +165,7 @@ def __gt__(self, other):
                         return True
                     elif q_negative(i):
                         return False
+
                 raise TypeError("Non-comparable index functions") from e
 
         return False
@@ -203,6 +205,7 @@ def __le__(self, other):
                         return True
                     elif q_positive(i):
                         return False
+
                 raise TypeError("Non-comparable index functions") from e
 
         # Note: unlike `__lt__`, if we end up here, then *it is* <=. For example,

devito/passes/clusters/asynchrony.py

@@ -1,6 +1,6 @@
 from collections import defaultdict
 
-from sympy import true
+from sympy import Mod, true
 
 from devito.ir import (
     Backward, Forward, GuardBoundNext, PrefetchUpdate, Queue, ReleaseLock, SyncArray,
@@ -78,7 +78,8 @@ def callback(self, clusters, prefix):
             d = self.key0(c0)
             if d is not dim:
                 continue
-
+            if d in c0.guards and not c0.guards[d].has(Mod):
+                continue
             protected = self._schedule_waitlocks(c0, d, clusters, locks, syncs)
             self._schedule_withlocks(c0, d, protected, locks, syncs)
 
@@ -193,7 +194,7 @@ def memcpy_prefetch(clusters, key0, sregistry):
         if c.properties.is_prefetchable(d._defines):
             _actions_from_update_memcpy(c, d, clusters, actions, sregistry)
         elif d.is_Custom and is_integer(c.ispace[d].size):
-            _actions_from_init(c, d, actions)
+            _actions_from_init(c, d, clusters, actions)
 
     # Attach the computed Actions
     processed = []
@@ -214,7 +215,7 @@ def memcpy_prefetch(clusters, key0, sregistry):
     return processed
 
 
-def _actions_from_init(c, d, actions):
+def _actions_from_init(c, d, clusters, actions):
     e = c.exprs[0]
     function = e.rhs.function
     target = e.lhs.function