Add test / note about $bits of large types

MikePopoloski · Apr 27, 2024 · f53dc6d · f53dc6d
1 parent a01388e
commit f53dc6d
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Showing 2 changed files with 17 additions and 1 deletion.
diff --git a/source/ast/builtins/QueryFuncs.cpp b/source/ast/builtins/QueryFuncs.cpp
@@ -61,7 +61,9 @@ class BitsFunction : public SystemSubroutine {
             width = cv.getBitstreamWidth();
         }
 
-        // TODO: handle overflow of 32 bits
+        // Note: we convert the size down to a 32-bit result. This can result
+        // in (defined) overflow, which matches the behavior of all other
+        // tools that I tried.
         return SVInt(32, width, true);
     }
 };

diff --git a/tests/unittests/ast/SystemFuncTests.cpp b/tests/unittests/ast/SystemFuncTests.cpp
@@ -1303,3 +1303,17 @@ endmodule
     compilation.addSyntaxTree(tree);
     NO_COMPILATION_ERRORS;
 }
+
+TEST_CASE("$bits of >32bit sized type") {
+    auto tree = SyntaxTree::fromText(R"(
+logic [7:0] a [2147483647];
+localparam p = $bits(a);
+)");
+
+    Compilation compilation;
+    compilation.addSyntaxTree(tree);
+    NO_COMPILATION_ERRORS;
+
+    auto& p = compilation.getCompilationUnits()[0]->find<ParameterSymbol>("p");
+    CHECK(p.getValue().integer() == -8);
+}