Address Erik's feedback

Author: lwaern-intel

py/dml/codegen.py

@@ -3055,7 +3055,7 @@ def stmt_select(stmt, location, scope):
                 if_chain = last_stmt
             else:
                 if_chain = codegen_statement(else_ast, location, scope)
-            if iterations > 50 and isinstance(lst, List):
+            if iterations > WBIGUNROLL.limit and isinstance(lst, List):
                 report(WBIGUNROLL(stmt.site,
                                   '#'*(stmt.site.dml_version() != (1, 2))
                                   + 'select',
@@ -3186,7 +3186,7 @@ def foreach_constant_list(site, itername, lst, statement, location, scope):
                     stmt)
             spec.append(mkCompound(site, decls + [stmt]))
 
-        if len(spec) > 50 and isinstance(lst, List):
+        if len(spec) > WBIGUNROLL.limit and isinstance(lst, List):
             report(WBIGUNROLL(site,
                               '#'*(site.dml_version() != (1, 2)) + 'foreach',
                               len(spec)))

py/dml/messages.py

@@ -2012,16 +2012,17 @@ class WHOOKSEND(DMLWarning):
            + "information about the differences between 'send' and 'send_now'")
 
 class WBIGUNROLL(DMLWarning):
-    """
+    limit = 64
+    __doc__ = f"""
     A `#select` or `#foreach` statement was specified which caused DMLC to
     study the body and generate duplicated C code for it a large number of
-    times (more than 50 times.) This can dramatically increase both DMLC and
-    GCC compile times and code size, if not crash DMLC outright.
+    times (more than {limit} times.) This can dramatically increase both DMLC
+    and GCC compile times and code size, if not crash DMLC outright.
 
     To address this, you have two options:
     * Ensure most iterations can be entirely eliminated at compile-time by
       DMLC. For `#select`, this can be done by ensuring that the `where` check
-      will be a constant (typically a constant equality) for most if not all
+      will be a constant value (e.g. a constant equality) for most if not all
       items of the specified list. For `#foreach`, encase the body in an `#if`
       check that is false for most items of the specified list.
     * Don't use `#select` or `#foreach`. Represent the specified compile-time

test/1.2/errors/T_WBIGUNROLL.dml

@@ -11,61 +11,64 @@ device test;
 
 data int zero = 0;
 
-parameter zeroes_50 = [$zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
+parameter zeroes_64 = [$zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
-                       $zero, $zero];
+                       $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
+                       $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero];
 
-// Fiftieth zero is constant
-parameter zeroes_51 = [$zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
+// Sixtyfourth zero is constant
+parameter zeroes_65 = [$zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
+                       $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
                        $zero, $zero, $zero, $zero, $zero, $zero, $zero, $zero,
-                       $zero, 0, $zero];
+                       $zero, $zero, $zero, $zero, $zero, $zero, $zero, 0,
+                       $zero];
 
 bank b {
-    register regs[i in 0..50] size 4 @ undefined;
+    register regs[i in 0..64] size 4 @ undefined;
 }
 
 method init {
-    local int i;
+    local int nonconstant;
 
     // no warning
-    foreach x in ($zeroes_50) assert true;
+    foreach x in ($zeroes_64) assert true;
     // The else branch is not considered an iteration
-    select x in ($zeroes_50) where (x == i) {
+    select x in ($zeroes_64) where (x == nonconstant) {
         assert true;
     } else assert true;
 
     /// WARNING WBIGUNROLL
-    foreach x in ($zeroes_51) assert true;
+    foreach x in ($zeroes_65) assert true;
     /// WARNING WBIGUNROLL
-    select x in ($zeroes_51) where (x == i) {
+    select x in ($zeroes_65) where (x == nonconstant) {
         assert true;
     } else assert true;
 
     // no warning
-    foreach x in ($zeroes_51) {
-        // As fiftieth bit is constant 0, DML 1.2 semantics eliminates this if
-        // entirely, and subsequently causes that iteration to be omitted from
-        // codegen entirely; reducing the total count to 50
+    foreach x in ($zeroes_65) {
+        // As sixtyfourth bit is constant 0, DML 1.2 semantics eliminates this
+        // if, and subsequently causes that iteration to be omitted from
+        // codegen entirely; reducing the total count to 64
         if (x != 0) assert true;
     }
 
-    // As fiftieth bit is constant 0, select can cut short at it, reducing the
-    // total number of iterations to 50
-    select x in ($zeroes_50) where (x == 0) {
+    // As sixtyfourth bit is constant 0, select can cut short at it, reducing
+    // the total number of iterations to 64
+    select x in ($zeroes_65) where (x == 0) {
         assert true;
     } else assert true;
 
-    // As fiftieth bit is constant 0, select can omit the check and thus
-    // iteration for it, reducing the total number of iterations to 50
-    select x in ($zeroes_50) where (x == 1) {
+    // As sixtyfourth bit is constant 0, select can omit the check and thus
+    // iteration for it, reducing the total number of iterations to 64
+    select x in ($zeroes_65) where (x != 0) {
         assert true;
     } else assert true;
 
@@ -74,7 +77,7 @@ method init {
     // syntax, not the object lists generated by DMLC
     // no warning
     foreach x in ($b.unmapped_registers) assert true;
-    select x in ($b.unmapped_registers) where (i == 0) {
+    select x in ($b.unmapped_registers) where (x == nonconstant) {
         assert true;
     } else assert true;
 }