[fuzzer] Enable loongarch64

Enable fuzzer on loongarch64.

Reviewed By: SixWeining, xen0n, MaskRay

Differential Revision: https://reviews.llvm.org/D140601

Author: Youling Tang

compiler-rt/cmake/Modules/AllSupportedArchDefs.cmake

@@ -40,7 +40,7 @@ endif()
 
 if(OS_NAME MATCHES "Linux")
   set(ALL_FUZZER_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${S390X}
-      ${RISCV64})
+      ${RISCV64} ${LOONGARCH64})
 elseif (OS_NAME MATCHES "Windows")
   set(ALL_FUZZER_SUPPORTED_ARCH ${X86} ${X86_64})
 elseif(OS_NAME MATCHES "Android")

compiler-rt/lib/fuzzer/FuzzerTracePC.cpp

@@ -149,8 +149,8 @@ inline ALWAYS_INLINE uintptr_t GetPreviousInstructionPc(uintptr_t PC) {
 ALWAYS_INLINE uintptr_t TracePC::GetNextInstructionPc(uintptr_t PC) {
 #if defined(__mips__)
   return PC + 8;
-#elif defined(__powerpc__) || defined(__sparc__) || defined(__arm__) || \
-    defined(__aarch64__)
+#elif defined(__powerpc__) || defined(__sparc__) || defined(__arm__) ||        \
+    defined(__aarch64__) || defined(__loongarch__)
   return PC + 4;
 #else
   return PC + 1;