[clang] [clang] [Static analyzer]: add initial support for builtin overflow (PR #102602)

[Balazs Benics via cfe-commits]

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@@ -0,0 +1,65 @@
+// RUN: %clang_analyze_cc1 -triple x86_64-unknown-unknown -verify %s \
+// RUN:   -analyzer-checker=core,debug.ExprInspection
+
+#define NULL ((void *)0)
+#define INT_MAX __INT_MAX__
+
+void clang_analyzer_dump_int(int);
+
+void test1(void)
+{
+   int res;
+
+   if (__builtin_add_overflow(10, 20, &res)) {
+     clang_analyzer_dump_int(res); //expected-warning{{1st function call argument is an uninitialized value}}
+     return;
+   }
+
+   clang_analyzer_dump_int(res); //expected-warning{{30}}
+}
+
+void test2(void)
+{
+   int res;
+
+   __builtin_add_overflow(10, 20, &res);
+   clang_analyzer_dump_int(res); //expected-warning{{1st function call argument is an uninitialized value}} expected-warning{{S32b}}
+}
+
+void test3(void)
+{
+   int res;
+
+   if (__builtin_sub_overflow(10, 20, &res)) {
+     clang_analyzer_dump_int(res); //expected-warning{{1st function call argument is an uninitialized value}}
+     return;
+   }
+
+   clang_analyzer_dump_int(res); //expected-warning{{-10}}
+}
+
+void test4(void)
+{
+   int res;
+
+   if (__builtin_sub_overflow(10, 20, &res)) {
+     clang_analyzer_dump_int(res); //expected-warning{{1st function call argument is an uninitialized value}}
+     return;
+   }
+
+   if (res != -10) {
+     *(volatile char *)NULL; //no warning
+   }
+}
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steakhal wrote:

This is already covered by `test3`

https://github.com/llvm/llvm-project/pull/102602