From 9442d3e3951a59420019a1588e894986832d7a51 Mon Sep 17 00:00:00 2001
From: Ehsan Totoni <ehsan.tn@gmail.com>
Date: Wed, 21 Aug 2019 10:21:18 -0400
Subject: [PATCH 1/3] Fix liveness for remove dead of parfors (and other IR
 extensions)

---
 numba/ir_utils.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/numba/ir_utils.py b/numba/ir_utils.py
index 67d2a5c50b3..3b0de01fc2a 100644
--- a/numba/ir_utils.py
+++ b/numba/ir_utils.py
@@ -548,7 +548,7 @@ def remove_dead_block(block, lives, call_table, arg_aliases, alias_map,
         # let external calls handle stmt if type matches
         if type(stmt) in remove_dead_extensions:
             f = remove_dead_extensions[type(stmt)]
-            stmt = f(stmt, lives, arg_aliases, alias_map, func_ir, typemap)
+            stmt = f(stmt, lives_n_aliases, arg_aliases, alias_map, func_ir, typemap)
             if stmt is None:
                 removed = True
                 continue

From 76127984dd88defaff9e31328553db2e2ef93121 Mon Sep 17 00:00:00 2001
From: Ehsan Totoni <ehsan.tn@gmail.com>
Date: Wed, 21 Aug 2019 11:17:20 -0400
Subject: [PATCH 2/3] test parfor aliasing in remove dead

---
 numba/ir_utils.py               |  3 +-
 numba/tests/test_remove_dead.py | 53 +++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/numba/ir_utils.py b/numba/ir_utils.py
index 3b0de01fc2a..d9967e13265 100644
--- a/numba/ir_utils.py
+++ b/numba/ir_utils.py
@@ -548,7 +548,8 @@ def remove_dead_block(block, lives, call_table, arg_aliases, alias_map,
         # let external calls handle stmt if type matches
         if type(stmt) in remove_dead_extensions:
             f = remove_dead_extensions[type(stmt)]
-            stmt = f(stmt, lives_n_aliases, arg_aliases, alias_map, func_ir, typemap)
+            stmt = f(stmt, lives_n_aliases, arg_aliases, alias_map, func_ir,
+                     typemap)
             if stmt is None:
                 removed = True
                 continue
diff --git a/numba/tests/test_remove_dead.py b/numba/tests/test_remove_dead.py
index 8c0d58d4649..914dce3ed97 100644
--- a/numba/tests/test_remove_dead.py
+++ b/numba/tests/test_remove_dead.py
@@ -213,5 +213,58 @@ def func(A, i):
             # recover global state
             numba.ir_utils.alias_func_extensions = old_ext_handlers
 
+    def test_alias_parfor_extension(self):
+        """Make sure aliases are considered in remove dead extension for
+        parfors.
+        """
+        def func():
+            n = 11
+            numba.parfor.init_prange()
+            A = np.empty(n)
+            B = A  # create alias to A
+            for i in numba.prange(n):
+                A[i] = i
+
+            return B
+
+        class TestPipeline(numba.compiler.Pipeline):
+            """Test pipeline that just converts prange() to parfor and calls
+            remove_dead(). Copy propagation can replace B in the example code
+            which this pipeline avoids.
+            """
+            def define_pipelines(self, pm):
+                pm.create_pipeline("test parfor aliasing")
+                self.add_preprocessing_stage(pm)
+                self.add_pre_typing_stage(pm)
+                self.add_typing_stage(pm)
+                pm.add_stage(
+                    self.stage_limited_parfor, "just prange and rm dead")
+                self.add_lowering_stage(pm)
+                self.add_cleanup_stage(pm)
+
+            def stage_limited_parfor(self):
+                parfor_pass = numba.parfor.ParforPass(
+                    self.func_ir,
+                    self.type_annotation.typemap,
+                    self.type_annotation.calltypes,
+                    self.return_type,
+                    self.typingctx,
+                    self.flags.auto_parallel,
+                    self.flags,
+                    self.parfor_diagnostics
+                )
+                remove_dels(self.func_ir.blocks)
+                parfor_pass.array_analysis.run(self.func_ir.blocks)
+                parfor_pass._convert_loop(self.func_ir.blocks)
+                remove_dead(self.func_ir.blocks, self.func_ir.arg_names,
+                    self.func_ir, self.type_annotation.typemap)
+                numba.parfor.get_parfor_params(self.func_ir.blocks,
+                    parfor_pass.options.fusion, parfor_pass.nested_fusion_info)
+
+        test_res = numba.jit(pipeline_class=TestPipeline)(func)()
+        py_res = func()
+        np.testing.assert_array_equal(test_res, py_res)
+
+
 if __name__ == "__main__":
     unittest.main()

From 57aea3bc980b968ad4456746b96c9411e9fc7cbb Mon Sep 17 00:00:00 2001
From: Ehsan Totoni <ehsan.tn@gmail.com>
Date: Thu, 22 Aug 2019 08:50:23 -0400
Subject: [PATCH 3/3] skip parfor test on unsupported platforms

---
 numba/tests/test_remove_dead.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/numba/tests/test_remove_dead.py b/numba/tests/test_remove_dead.py
index 914dce3ed97..40b2dd61a92 100644
--- a/numba/tests/test_remove_dead.py
+++ b/numba/tests/test_remove_dead.py
@@ -213,6 +213,7 @@ def func(A, i):
             # recover global state
             numba.ir_utils.alias_func_extensions = old_ext_handlers
 
+    @skip_parfors_unsupported
     def test_alias_parfor_extension(self):
         """Make sure aliases are considered in remove dead extension for
         parfors.