Merge pull request #5627 from stuartarchibald/fix/5623

Fixes #5623, SSA local def scan based on invalid equality assumption.

numba/core/ssa.py

@@ -430,15 +430,18 @@ def _find_def_from_bottom(self, states, label, loc):
             return self._find_def_from_top(states, label, loc=loc)
 
     def _stmt_index(self, defstmt, block, stop=-1):
-        """Find the postitional index of the statement at ``block``.
+        """Find the positional index of the statement at ``block``.
 
         Assumptions:
         - no two statements can point to the same object.
         """
-        try:
-            return block.body.index(defstmt, 0, stop)
-        except ValueError:
-            return len(block.body)
+        # Compare using id() as IR node equality is for semantic equivalence
+        # opposed to direct equality (the location and scope are not considered
+        # as part of the equality measure, this is important here).
+        for i in range(len(block.body))[:stop]:
+            if block.body[i] is defstmt:
+                return i
+        return len(block.body)
 
 
 def _warn_about_uninitialized_variable(varname, loc):

numba/tests/test_ssa.py

@@ -370,3 +370,26 @@ def foo(m, n, data):
         res2 = jit(forceobj=True, looplift=False)(foo)(10, 10, data)
         np.testing.assert_array_equal(expect, res1)
         np.testing.assert_array_equal(expect, res2)
+
+    def test_issue5623_equal_statements_in_same_bb(self):
+
+        def foo(pred, stack):
+            i = 0
+            c = 1
+
+            if pred is True:
+                stack[i] = c
+                i += 1
+                stack[i] = c
+                i += 1
+
+        python = np.array([0, 666])
+        foo(True, python)
+
+        nb = np.array([0, 666])
+        njit(foo)(True, nb)
+
+        expect = np.array([1, 1])
+
+        np.testing.assert_array_equal(python, expect)
+        np.testing.assert_array_equal(nb, expect)