[MemProf] Use correct print_text value

[ellishg]

Use the correct value for print_text in FinishAndWrite().

This value was initialized in the constructor of a global variable

llvm-project/compiler-rt/lib/memprof/memprof_allocator.cpp

Line 641 in 65683b0

static Allocator instance(LINKER_INITIALIZED);

The flag values in flags() are populated in InitializeFlags(), which is also called in a constructor of a global variable

llvm-project/compiler-rt/lib/memprof/memprof_rtl.cpp

Lines 241 to 255 in 65683b0

	// Initialize as requested from some part of MemProf runtime library
	// (interceptors, allocator, etc).
	void MemprofInitFromRtl() { MemprofInitInternal(); }
	#if MEMPROF_DYNAMIC
	// Initialize runtime in case it's LD_PRELOAD-ed into uninstrumented executable
	// (and thus normal initializers from .preinit_array or modules haven't run).
	class MemprofInitializer {
	public:
	MemprofInitializer() { MemprofInitFromRtl(); }
	};
	static MemprofInitializer memprof_initializer;
	#endif // MEMPROF_DYNAMIC

I think the order that these two functions run is undefined, and the value of the field print_text depends on this order when the user overrides default values.

[llvmbot]

@llvm/pr-subscribers-pgo

Author: Ellis Hoag (ellishg)

Changes

Use the correct value for print_text in FinishAndWrite().

This value was initialized in the constructor of a global variable

llvm-project/compiler-rt/lib/memprof/memprof_allocator.cpp

Line 641 in 65683b0

static Allocator instance(LINKER_INITIALIZED);

The flag values in flags() are populated in InitializeFlags(), which is also called in a constructor of a global variable

llvm-project/compiler-rt/lib/memprof/memprof_rtl.cpp

Lines 241 to 255 in 65683b0

	// Initialize as requested from some part of MemProf runtime library
	// (interceptors, allocator, etc).
	void MemprofInitFromRtl() { MemprofInitInternal(); }
	#if MEMPROF_DYNAMIC
	// Initialize runtime in case it's LD_PRELOAD-ed into uninstrumented executable
	// (and thus normal initializers from .preinit_array or modules haven't run).
	class MemprofInitializer {
	public:
	MemprofInitializer() { MemprofInitFromRtl(); }
	};
	static MemprofInitializer memprof_initializer;
	#endif // MEMPROF_DYNAMIC

I think the order that these two functions run is undefined, and the value of the field print_text depends on this order when the user overrides default values.

---

Full diff: https://github.com/llvm/llvm-project/pull/125793.diff

1 Files Affected:

• (modified) compiler-rt/lib/memprof/memprof_allocator.cpp (+3-4)

diff --git a/compiler-rt/lib/memprof/memprof_allocator.cpp b/compiler-rt/lib/memprof/memprof_allocator.cpp
index c3448c22532bb89..60f5c853f9d76ff 100644
--- a/compiler-rt/lib/memprof/memprof_allocator.cpp
+++ b/compiler-rt/lib/memprof/memprof_allocator.cpp
@@ -291,10 +291,9 @@ struct Allocator {
 
   atomic_uint8_t destructing;
   atomic_uint8_t constructed;
-  bool print_text;
 
   // ------------------- Initialization ------------------------
-  explicit Allocator(LinkerInitialized) : print_text(flags()->print_text) {
+  explicit Allocator(LinkerInitialized) {
     atomic_store_relaxed(&destructing, 0);
     atomic_store_relaxed(&constructed, 1);
   }
@@ -350,13 +349,13 @@ struct Allocator {
   }
 
   void FinishAndWrite() {
-    if (print_text && common_flags()->print_module_map)
+    if (flags()->print_text && common_flags()->print_module_map)
       DumpProcessMap();
 
     allocator.ForceLock();
 
     InsertLiveBlocks();
-    if (print_text) {
+    if (flags()->print_text) {
       if (!flags()->print_terse)
         Printf("Recorded MIBs (incl. live on exit):\n");
       MIBMap.ForEach(PrintCallback,