Merge #15985: Add test for GCC bug 90348

58e291c Add test for GCC bug 90348 (Pieter Wuille)

Pull request description:

  This adds a test for GCC bug 90348 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90348), using a test case extracted from our own `sha256d64` test in crypto_tests.cpp, which was failing on some platforms.

  This is based on top of #15983 to make sure the bug doesn't trigger (it does in some Travis configurations without it).

ACKs for commit 58e291:

Tree-SHA512: 4dc9084e92dd143a53930e42bb68e33d922a2a2b891406b259d3a0bed4511dcc49e7447a7a8e4eb793a26e3eacb188ca293b71e0e061f9b3230f8e7fcfd29525

Author: laanwj

src/Makefile.test.include

@@ -97,6 +97,7 @@ BITCOIN_TESTS =\
   test/bswap_tests.cpp \
   test/checkqueue_tests.cpp \
   test/coins_tests.cpp \
+  test/compilerbug_tests.cpp \
   test/compress_tests.cpp \
   test/crypto_tests.cpp \
   test/cuckoocache_tests.cpp \

src/test/compilerbug_tests.cpp

@@ -0,0 +1,43 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <test/setup_common.h>
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(compilerbug_tests, BasicTestingSetup)
+
+#if defined(__GNUC__)
+// This block will also be built under clang, which is fine (as it supports noinline)
+void __attribute__ ((noinline)) set_one(unsigned char* ptr)
+{
+    *ptr = 1;
+}
+
+int __attribute__ ((noinline)) check_zero(unsigned char const* in, unsigned int len)
+{
+    for (unsigned int i = 0; i < len; ++i) {
+        if (in[i] != 0) return 0;
+    }
+    return 1;
+}
+
+void set_one_on_stack() {
+    unsigned char buf[1];
+    set_one(buf);
+}
+
+BOOST_AUTO_TEST_CASE(gccbug_90348) {
+    // Test for GCC bug 90348. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90348
+    for (int i = 0; i <= 4; ++i) {
+        unsigned char in[4];
+        for (int j = 0; j < i; ++j) {
+            in[j] = 0;
+            set_one_on_stack(); // Apparently modifies in[0]
+        }
+        BOOST_CHECK(check_zero(in, i));
+    }
+}
+#endif
+
+BOOST_AUTO_TEST_SUITE_END()