[scudo] Add utilization percentages for stats. (#75101)

Refactor the percentage display in the secondary code. Re-use that to
display a utilization percentage when displaying fragmentation data.

Author: cferris1000

compiler-rt/lib/scudo/standalone/common.h

@@ -112,6 +112,21 @@ template <typename T> inline void shuffle(T *A, u32 N, u32 *RandState) {
   *RandState = State;
 }
 
+inline void computePercentage(uptr Numerator, uptr Denominator, uptr *Integral,
+                              uptr *Fractional) {
+  constexpr uptr Digits = 100;
+  if (Denominator == 0) {
+    *Integral = 100;
+    *Fractional = 0;
+    return;
+  }
+
+  *Integral = Numerator * Digits / Denominator;
+  *Fractional =
+      (((Numerator * Digits) % Denominator) * Digits + Denominator / 2) /
+      Denominator;
+}
+
 // Platform specific functions.
 
 extern uptr PageSizeCached;

compiler-rt/lib/scudo/standalone/primary32.h

@@ -931,10 +931,14 @@ template <typename Config> class SizeClassAllocator32 {
         AllocatedPagesCount - Recorder.getReleasedPagesCount();
     const uptr InUseBytes = InUsePages * PageSize;
 
+    uptr Integral;
+    uptr Fractional;
+    computePercentage(BlockSize * InUseBlocks, InUsePages * PageSize, &Integral,
+                      &Fractional);
     Str->append("  %02zu (%6zu): inuse/total blocks: %6zu/%6zu inuse/total "
-                "pages: %6zu/%6zu inuse bytes: %6zuK\n",
+                "pages: %6zu/%6zu inuse bytes: %6zuK util: %3zu.%02zu%%\n",
                 ClassId, BlockSize, InUseBlocks, TotalBlocks, InUsePages,
-                AllocatedPagesCount, InUseBytes >> 10);
+                AllocatedPagesCount, InUseBytes >> 10, Integral, Fractional);
   }
 
   NOINLINE uptr releaseToOSMaybe(SizeClassInfo *Sci, uptr ClassId,

compiler-rt/lib/scudo/standalone/primary64.h

@@ -1130,10 +1130,14 @@ template <typename Config> class SizeClassAllocator64 {
         AllocatedPagesCount - Recorder.getReleasedPagesCount();
     const uptr InUseBytes = InUsePages * PageSize;
 
+    uptr Integral;
+    uptr Fractional;
+    computePercentage(BlockSize * InUseBlocks, InUsePages * PageSize, &Integral,
+                      &Fractional);
     Str->append("  %02zu (%6zu): inuse/total blocks: %6zu/%6zu inuse/total "
-                "pages: %6zu/%6zu inuse bytes: %6zuK\n",
+                "pages: %6zu/%6zu inuse bytes: %6zuK util: %3zu.%02zu%%\n",
                 ClassId, BlockSize, InUseBlocks, TotalBlocks, InUsePages,
-                AllocatedPagesCount, InUseBytes >> 10);
+                AllocatedPagesCount, InUseBytes >> 10, Integral, Fractional);
   }
 
   NOINLINE uptr releaseToOSMaybe(RegionInfo *Region, uptr ClassId,

compiler-rt/lib/scudo/standalone/secondary.h

@@ -155,20 +155,16 @@ template <typename Config> class MapAllocatorCache {
 
   void getStats(ScopedString *Str) {
     ScopedLock L(Mutex);
-    u32 Integral = 0;
-    u32 Fractional = 0;
-    if (CallsToRetrieve != 0) {
-      Integral = SuccessfulRetrieves * 100 / CallsToRetrieve;
-      Fractional = (((SuccessfulRetrieves * 100) % CallsToRetrieve) * 100 +
-                    CallsToRetrieve / 2) /
-                   CallsToRetrieve;
-    }
+    uptr Integral;
+    uptr Fractional;
+    computePercentage(SuccessfulRetrieves, CallsToRetrieve, &Integral,
+                      &Fractional);
     Str->append("Stats: MapAllocatorCache: EntriesCount: %d, "
                 "MaxEntriesCount: %u, MaxEntrySize: %zu\n",
                 EntriesCount, atomic_load_relaxed(&MaxEntriesCount),
                 atomic_load_relaxed(&MaxEntrySize));
     Str->append("Stats: CacheRetrievalStats: SuccessRate: %u/%u "
-                "(%u.%02u%%)\n",
+                "(%zu.%02zu%%)\n",
                 SuccessfulRetrieves, CallsToRetrieve, Integral, Fractional);
     for (CachedBlock Entry : Entries) {
       if (!Entry.isValid())