feat: optimize few host instructions from trace of SD and LD

src/Makefile

@@ -214,14 +214,18 @@ SHA3_CFLAGS=-O3
 # Optimization flags for the interpreter
 ifneq (,$(filter yes,$(relwithdebinfo) $(release)))
 ifneq (,$(findstring gcc,$(CC)))
-# The following is known to improve the interpret loop efficiency
-INTERPRET_CXXFLAGS+=-fgcse-after-reload -fgcse-sm
+# The following improves computed goto dispatch as stated in GCC manual
+INTERPRET_CXXFLAGS+=-fno-gcse
+# The following remove extra jumps in the computed goto dispatch
+INTERPRET_CXXFLAGS+=-fno-crossjumping
+# The following remove extra NOPs before jumping back to the interpret hot loop
+INTERPRET_CXXFLAGS+=-fno-align-loops
 # The interpreter dispatch loop performs better as a big inlined function
 INTERPRET_CXXFLAGS+=-finline-limit=1024
 # The interpreter hot loop is big and puts pressure on register allocation, this improves register use
 INTERPRET_CXXFLAGS+=-frename-registers -fweb
 # The interpreter instruction dispatch is big, the following reduces its size minimizing CPU cache pressure
-INTERPRET_CXXFLAGS+=-freorder-blocks-algorithm=simple -fno-align-loops
+INTERPRET_CXXFLAGS+=-freorder-blocks-algorithm=simple
 # Some distributions enables stack protector by default, make sure it's disabled
 INTERPRET_CXXFLAGS+=-fno-stack-protector
 endif

src/interpret.cpp

@@ -890,8 +890,10 @@ static FORCE_INLINE bool read_virtual_memory(STATE_ACCESS a, uint64_t &pc, uint6
     if (unlikely(!(a.template read_memory_word_via_tlb<TLB_READ>(vaddr, pval)))) {
         // Outline the slow path into a function call to minimize host CPU code cache pressure
         INC_COUNTER(a.get_statistics(), tlb_rmiss);
+        T val = 0; // Don't pass pval reference directly so the compiler can store it in a register
         auto [status, new_pc] =
-            read_virtual_memory_slow<T, STATE_ACCESS, RAISE_STORE_EXCEPTIONS>(a, pc, mcycle, vaddr, pval);
+            read_virtual_memory_slow<T, STATE_ACCESS, RAISE_STORE_EXCEPTIONS>(a, pc, mcycle, vaddr, &val);
+        *pval = val;
         pc = new_pc;
         return status;
     }