[clang][asan] Add test for ensuring PR52382 is fixed

[leonardchan]

Summary

The fix for PR52382 was already introduced in D112732 which ensures that module instrumentation always runs after function instrumentation. This adds a test that ensures the PR is addressed and prevent regression.

clang/test/CodeGen/pr52382.c

+// RUN: %clang -target x86_64-unknown-linux-gnu -S -emit-llvm -o - -fsanitize=address %s | FileCheck %s
+
+// Ensure that ASan properly instruments a load into a global where the index
+// happens to be within the padding after the global which is used for the
+// redzone.
+
+// This global is 400 bytes long, but gets padded with 112 bytes for redzones,
+// rounding the total size after instrumentation to 512.
+int global_array[100] = {-1};
+
+// This access is 412 bytes after the start of the global: past the end of the
+// uninstrumented array, but within the bounds of the extended instrumented
+// array. We should ensure this is still instrumented.
+int main(void) { return global_array[103]; }
+
+// CHECK: @main
+// CHECK-NEXT: entry:
+// CHECK: call void @__asan_report_load4
+// CHECK: }