From ff53f3d2b6e267358cf4c3d08574416c79441ef9 Mon Sep 17 00:00:00 2001
From: Merry <git@mary.rs>
Date: Wed, 13 Dec 2023 12:02:30 +0000
Subject: [PATCH] cxxrtl: Fix value::shl

---
 Makefile                                |  1 +
 backends/cxxrtl/runtime/cxxrtl/cxxrtl.h |  1 +
 tests/cxxrtl/.gitignore                 |  1 +
 tests/cxxrtl/run-test.sh                | 12 ++++++++++++
 tests/cxxrtl/test_value.cc              | 15 +++++++++++++++
 5 files changed, 30 insertions(+)
 create mode 100644 tests/cxxrtl/.gitignore
 create mode 100755 tests/cxxrtl/run-test.sh
 create mode 100644 tests/cxxrtl/test_value.cc

diff --git a/Makefile b/Makefile
index 8f3e473ea..8a72e3c70 100644
--- a/Makefile
+++ b/Makefile
@@ -888,6 +888,7 @@ endif
 	+cd tests/verilog && bash run-test.sh
 	+cd tests/xprop && bash run-test.sh $(SEEDOPT)
 	+cd tests/fmt && bash run-test.sh
+	+cd tests/cxxrtl && bash run-test.sh
 	@echo ""
 	@echo "  Passed \"make test\"."
 	@echo ""
diff --git a/backends/cxxrtl/runtime/cxxrtl/cxxrtl.h b/backends/cxxrtl/runtime/cxxrtl/cxxrtl.h
index 2d5451287..635c867ae 100644
--- a/backends/cxxrtl/runtime/cxxrtl/cxxrtl.h
+++ b/backends/cxxrtl/runtime/cxxrtl/cxxrtl.h
@@ -419,6 +419,7 @@ struct value : public expr_base<value<Bits>> {
 			carry = (shift_bits == 0) ? 0
 				: data[n] >> (chunk::bits - shift_bits);
 		}
+		result.data[result.chunks - 1] &= result.msb_mask;
 		return result;
 	}
 
diff --git a/tests/cxxrtl/.gitignore b/tests/cxxrtl/.gitignore
new file mode 100644
index 000000000..91caee986
--- /dev/null
+++ b/tests/cxxrtl/.gitignore
@@ -0,0 +1 @@
+cxxrtl-test-*
diff --git a/tests/cxxrtl/run-test.sh b/tests/cxxrtl/run-test.sh
new file mode 100755
index 000000000..473a5a349
--- /dev/null
+++ b/tests/cxxrtl/run-test.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -ex
+
+run_subtest () {
+    local subtest=$1; shift
+
+    ${CC:-gcc} -std=c++11 -o cxxrtl-test-${subtest} -I../../backends/cxxrtl/runtime test_${subtest}.cc -lstdc++
+    ./cxxrtl-test-${subtest}
+}
+
+run_subtest value
diff --git a/tests/cxxrtl/test_value.cc b/tests/cxxrtl/test_value.cc
new file mode 100644
index 000000000..ca05b89ab
--- /dev/null
+++ b/tests/cxxrtl/test_value.cc
@@ -0,0 +1,15 @@
+#include <cassert>
+#include <cstdint>
+
+#include "cxxrtl/cxxrtl.h"
+
+int main()
+{
+    {
+        // shl exceeding Bits should be masked
+        cxxrtl::value<6> a(1u);
+        cxxrtl::value<6> b(8u);
+        cxxrtl::value<6> c = a.shl(b);
+        assert(c.get<uint64_t>() == 0);
+    }
+}
\ No newline at end of file