[scudo] Limit stack depot size on Trusty

[ahomescu]

Summary

The stack depot uses several megabytes of memory
which is a lot for Trusty.

[Chia-hungDuan]

The failed tests look promising, could you take a look?

[ahomescu]

Fixed incorrect ifdef use.

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

 #ifndef SCUDO_CAN_USE_PRIMARY64
 #define SCUDO_CAN_USE_PRIMARY64 (SCUDO_WORDSIZE == 64U)
 #endif
 
 #ifndef SCUDO_CAN_USE_MTE
 #define SCUDO_CAN_USE_MTE (SCUDO_LINUX || SCUDO_TRUSTY)
 #endif
 
+// Use smaller table sizes for fuzzing in order to reduce input size.
+// Trusty just has less available memory.
+#ifndef SCUDO_SMALL_STACK_DEPOT
+#define SCUDO_SMALL_STACK_DEPOT (SCUDO_FUZZ || SCUDO_TRUSTY)
+#endif
+
 #ifndef SCUDO_MIN_ALIGNMENT_LOG
 // We force malloc-type functions to be aligned to std::max_align_t, but there
 // is no reason why the minimum alignment for all other functions can't be 8
 // bytes. Except obviously for applications making incorrect assumptions.
 // TODO(kostyak): define SCUDO_MIN_ALIGNMENT_LOG 3
 #define SCUDO_MIN_ALIGNMENT_LOG FIRST_32_SECOND_64(3, 4)
 #endif
 

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

class StackDepot {
   //
   // The insert() function is potentially racy in its accesses to the Tab and
   // Ring arrays, but find() is resilient to races in the sense that, barring
   // hash collisions, it will either return the correct stack trace or no stack
   // trace at all, even if two instances of insert() raced with one another.
   // This is achieved by re-checking the hash of the stack trace before
   // returning the trace.
 
-#ifdef SCUDO_FUZZ
-  // Use smaller table sizes for fuzzing in order to reduce input size.
+#if SCUDO_SMALL_STACK_DEPOT
   static const uptr TabBits = 4;
 #else
   static const uptr TabBits = 16;
 #endif
   static const uptr TabSize = 1 << TabBits;
   static const uptr TabMask = TabSize - 1;
   atomic_u32 Tab[TabSize] = {};
 
-#ifdef SCUDO_FUZZ
+#ifdef SCUDO_SMALL_STACK_DEPOT
   static const uptr RingBits = 4;
 #else
   static const uptr RingBits = 19;
 #endif
   static const uptr RingSize = 1 << RingBits;
   static const uptr RingMask = RingSize - 1;
   atomic_u64 Ring[RingSize] = {};