[BOLT] Add a test for BOLT-reserved space in a binary (#91399)

Test case for #90300.

Author: maksfb

bolt/test/runtime/bolt-reserved.cpp

@@ -0,0 +1,40 @@
+// REQUIRES: system-linux
+
+/*
+ * Check that llvm-bolt uses reserved space in a binary for allocating
+ * new sections.
+ */
+
+// RUN: %clang %s -o %t.exe -Wl,-q
+// RUN: llvm-bolt %t.exe -o %t.bolt.exe 2>&1 | FileCheck %s
+// RUN: %t.bolt.exe
+
+// CHECK: BOLT-INFO: using reserved space
+
+/*
+ * Check that llvm-bolt detects a condition when the reserved space is
+ * not enough for allocating new sections.
+ */
+
+// RUN: %clang %s -o %t.exe -Wl,--no-eh-frame-hdr -Wl,-q -DTINY
+// RUN: not llvm-bolt %t.exe -o %t.bolt.exe 2>&1 | \
+// RUN:   FileCheck %s --check-prefix=CHECK-TINY
+
+// CHECK-TINY: BOLT-ERROR: reserved space (1 byte) is smaller than required
+
+#ifdef TINY
+#define RSIZE "1"
+#else
+#define RSIZE "8192 * 1024"
+#endif
+
+asm(".pushsection .text \n\
+       .globl __bolt_reserved_start \n\
+       .type __bolt_reserved_start, @object \n\
+       __bolt_reserved_start: \n\
+       .space " RSIZE " \n\
+       .globl __bolt_reserved_end \n\
+       __bolt_reserved_end: \n\
+     .popsection");
+
+int main() { return 0; }