From fc63161985f74b6dda631044295fcfde0789acc2 Mon Sep 17 00:00:00 2001
From: Kaushik Kulkarni <kaushikcfd@gmail.com>
Date: Tue, 5 Jul 2022 19:09:14 -0500
Subject: [PATCH] Defines lp.VectorizationFallback

---
 loopy/__init__.py          |  4 ++--
 loopy/target/__init__.py   | 24 ++++++++++++++++++++++++
 loopy/target/c/__init__.py |  5 +++++
 loopy/target/cuda.py       |  5 +++++
 loopy/target/ispc.py       |  5 +++++
 loopy/target/opencl.py     |  5 +++++
 6 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/loopy/__init__.py b/loopy/__init__.py
index ce3ba1439..62529016e 100644
--- a/loopy/__init__.py
+++ b/loopy/__init__.py
@@ -150,7 +150,7 @@
 from loopy.frontend.fortran import (c_preprocess, parse_transformed_fortran,
         parse_fortran)
 
-from loopy.target import TargetBase, ASTBuilderBase
+from loopy.target import TargetBase, ASTBuilderBase, VectorizationFallback
 from loopy.target.c import (CFamilyTarget, CTarget, ExecutableCTarget,
                             generate_header, CWithGNULibcTarget,
                             ExecutableCWithGNULibcTarget)
@@ -298,7 +298,7 @@
 
         "LoopyError", "LoopyWarning",
 
-        "TargetBase",
+        "TargetBase", "VectorizationFallback",
         "CFamilyTarget", "CTarget", "ExecutableCTarget", "generate_header",
         "CWithGNULibcTarget", "ExecutableCWithGNULibcTarget",
         "CudaTarget", "OpenCLTarget",
diff --git a/loopy/target/__init__.py b/loopy/target/__init__.py
index ea7eec072..aedb0bd50 100644
--- a/loopy/target/__init__.py
+++ b/loopy/target/__init__.py
@@ -10,6 +10,7 @@
 .. autoclass:: OpenCLTarget
 .. autoclass:: PyOpenCLTarget
 .. autoclass:: ISPCTarget
+.. autoclass:: VectorizationFallback
 
 References to Canonical Names
 -----------------------------
@@ -50,6 +51,7 @@
 from typing import (Any, Tuple, Generic, TypeVar, Sequence, ClassVar, Optional,
         TYPE_CHECKING, Type)
 import abc
+from enum import Enum, unique
 
 if TYPE_CHECKING:
     from loopy.typing import ExpressionT
@@ -60,12 +62,30 @@
 ASTType = TypeVar("ASTType")
 
 
+@unique
+class VectorizationFallback(Enum):
+    """
+    Directs :mod:`loopy`\'s code-generation pipeline how the code should be
+    generated if an instruction cannot be vectorized.
+
+    :attr UNROLL: Unrolls the instances the unvectorizable statement.
+    :attr UNROLL: Wraps the statement around a loop with an ``omp simd``
+        pragma-directive.
+    """
+    UNROLL = 0
+    OMP_SIMD = 1
+
+
 class TargetBase(abc.ABC):
     """Base class for all targets, i.e. different combinations of code that
     loopy can generate.
 
     Objects of this type must be picklable.
 
+    .. attribute:: vectorization_fallback
+
+        An instance of :class:`VectorizationFallback`.
+
     .. attribute:: allows_non_constant_indexing_for_vec_types
 
         An instance of :class:`bool` that is *True* only if the target
@@ -178,6 +198,10 @@ def is_executable(self) -> bool:
         translation units through :attr:`loopy.TranslationUnit.__call__`.
         """
 
+    @abc.abstractproperty
+    def vectorization_fallback(self):
+        pass
+
     @abc.abstractproperty
     def allows_non_constant_indexing_for_vec_types(self):
         pass
diff --git a/loopy/target/c/__init__.py b/loopy/target/c/__init__.py
index e266ab073..beba25239 100644
--- a/loopy/target/c/__init__.py
+++ b/loopy/target/c/__init__.py
@@ -1375,6 +1375,11 @@ def allows_non_constant_indexing_for_vec_types(self):
     def broadcasts_scalar_assignment_to_vec_types(self):
         return False
 
+    @property
+    def vectorization_fallback(self):
+        from loopy.target import VectorizationFallback
+        return VectorizationFallback.UNROLL
+
 
 class CASTBuilder(CFamilyASTBuilder):
     def preamble_generators(self):
diff --git a/loopy/target/cuda.py b/loopy/target/cuda.py
index 2c6f97f53..f8850ff96 100644
--- a/loopy/target/cuda.py
+++ b/loopy/target/cuda.py
@@ -276,6 +276,11 @@ def allows_non_constant_indexing_for_vec_types(self):
     def broadcasts_scalar_assignment_to_vec_types(self):
         return True
 
+    @property
+    def vectorization_fallback(self):
+        from loopy.target import VectorizationFallback
+        return VectorizationFallback.UNROLL
+
 # }}}
 
 
diff --git a/loopy/target/ispc.py b/loopy/target/ispc.py
index a54ece4f7..b02a93a0a 100644
--- a/loopy/target/ispc.py
+++ b/loopy/target/ispc.py
@@ -210,6 +210,11 @@ def allows_non_constant_indexing_for_vec_types(self):
     def broadcasts_scalar_assignment_to_vec_types(self):
         return True
 
+    @property
+    def vectorization_fallback(self):
+        from loopy.target import VectorizationFallback
+        return VectorizationFallback.UNROLL
+
 
 class ISPCASTBuilder(CFamilyASTBuilder):
     # {{{ top-level codegen
diff --git a/loopy/target/opencl.py b/loopy/target/opencl.py
index fe971d4d2..7690eae63 100644
--- a/loopy/target/opencl.py
+++ b/loopy/target/opencl.py
@@ -606,6 +606,11 @@ def allows_non_constant_indexing_for_vec_types(self):
     def broadcasts_scalar_assignment_to_vec_types(self):
         return True
 
+    @property
+    def vectorization_fallback(self):
+        from loopy.target import VectorizationFallback
+        return VectorizationFallback.UNROLL
+
 # }}}