Add __CYCLES__ variable to count cycles used by instructions (#2171)

include/asm/section.hpp

@@ -40,6 +40,7 @@ struct Section {
 	uint16_t alignOfs;
 	std::deque<Patch> patches;
 	std::vector<uint8_t> data;
+	uint32_t cyclesCounter; // `__CYCLES__` value; unsigned for well-defined overflow on increment
 
 	SectionTypeInfo const &typeInfo() const { return sectionTypeInfo[type]; }
 

include/asm/symbol.hpp

@@ -83,6 +83,7 @@ Symbol *sym_RedefEqu(InternedStr symName, int32_t value);
 Symbol *sym_AddVar(InternedStr symName, int32_t value);
 int32_t sym_GetRSValue();
 void sym_SetRSValue(int32_t value);
+void sym_IncrementCYCLESValue(uint32_t delta);
 // Find a symbol by exact name, bypassing expansion checks
 Symbol *sym_FindExactSymbol(InternedStr symName);
 // Find a symbol, possibly scoped, by name