From 7f6762a0540b01062df5cb8ea4236dcfb2773474 Mon Sep 17 00:00:00 2001
From: Fabio Luporini <fabio@devitocodes.com>
Date: Thu, 4 Jul 2024 14:01:37 +0000
Subject: [PATCH] compiler: Default to index-mode=int32

---
 devito/core/operator.py | 6 +++---
 devito/types/dense.py   | 9 +++++----
 tests/test_linearize.py | 6 +++---
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/devito/core/operator.py b/devito/core/operator.py
index fa0baa11f24..390f2469d72 100644
--- a/devito/core/operator.py
+++ b/devito/core/operator.py
@@ -115,10 +115,10 @@ class BasicOperator(Operator):
     stencil-like data accesses.
     """
 
-    INDEX_MODE = "int64"
+    INDEX_MODE = "int32"
     """
-    The type of the expression used to compute array indices. Either `int64`
-    (default) or `int32`.
+    The type of the expression used to compute array indices. Either `int32`
+    (default) or `int64`.
     """
 
     ERRCTL = None
diff --git a/devito/types/dense.py b/devito/types/dense.py
index 5060b57746a..dfae835c5b7 100644
--- a/devito/types/dense.py
+++ b/devito/types/dense.py
@@ -866,10 +866,11 @@ def _arg_check(self, args, intervals, **kwargs):
         if args.options['index-mode'] == 'int32' and \
            args.options['linearize'] and \
            data.size - 1 >= np.iinfo(np.int32).max:
-            raise InvalidArgument("`%s`, with its %d elements, may be too big for "
-                                  "int32 pointer arithmetic, which might cause an "
-                                  "overflow. Use the 'index-mode=int64' option"
-                                  % (self, data.size))
+            raise InvalidArgument("`%s`, with its %d elements, is too big for "
+                                  "int32 pointer arithmetic. Consider using the "
+                                  "'index-mode=int64' option, the save=Buffer(..) "
+                                  "API (TimeFunction only), or domain "
+                                  "decomposition via MPI" % (self.name, data.size))
 
     def _arg_finalize(self, args, alias=None):
         key = alias or self
diff --git a/tests/test_linearize.py b/tests/test_linearize.py
index d4e23ecc03a..0a95d1e3f34 100644
--- a/tests/test_linearize.py
+++ b/tests/test_linearize.py
@@ -185,7 +185,7 @@ def test_codegen_quality0(mode):
 
     exprs = FindNodes(Expression).visit(op)
     assert len(exprs) == 6
-    assert all('const long' in str(i) for i in exprs[:-2])
+    assert all('const int' in str(i) for i in exprs[:-2])
 
     # Only four access macros necessary, namely `uL0`, `bufL0`, `bufL1`
     # for the efunc args
@@ -207,8 +207,8 @@ def test_codegen_quality1():
     # 11 expressions in total are expected, 8 of which are for the linearized accesses
     exprs = FindNodes(Expression).visit(op)
     assert len(exprs) == 11
-    assert all('const long' in str(i) for i in exprs[:-3])
-    assert all('const long' not in str(i) for i in exprs[-3:])
+    assert all('const int' in str(i) for i in exprs[:-3])
+    assert all('const int' not in str(i) for i in exprs[-3:])
 
     # Only two access macros necessary, namely `uL0` and `r1L0` (the other five
     # obviously are _POSIX_C_SOURCE, MIN, MAX, START, STOP)