afl-llvm-optimize.diff

--- llvm_mode/afl-llvm-pass.so.cc.orig	2019-01-03 19:37:23.641280087 +0100
+++ llvm_mode/afl-llvm-pass.so.cc	2019-01-04 10:31:02.999576722 +0100
@@ -31,12 +31,22 @@
 #include <stdlib.h>
 #include <unistd.h>
 
+#include "llvm/IR/BasicBlock.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/CFG.h"
+#include <algorithm>
 
 using namespace llvm;
 
@@ -69,6 +79,7 @@
 
   IntegerType *Int8Ty  = IntegerType::getInt8Ty(C);
   IntegerType *Int32Ty = IntegerType::getInt32Ty(C);
+  unsigned int cur_loc = 0;
 
   /* Show a banner */
 
@@ -118,7 +129,32 @@
 
       /* Make up cur_loc */
 
-      unsigned int cur_loc = AFL_R(MAP_SIZE);
+       //cur_loc++;
+      cur_loc = AFL_R(MAP_SIZE);
+
+      // only instrument if this basic block is the destination of a previous
+      // basic block that has multiple successors
+      // this gets rid of ~5-10% of instrumentations that are unnecessary
+      // result: a little more speed and less map pollution
+      int more_than_one = -1;
+      //fprintf(stderr, "BB %u: ", cur_loc);
+      for (BasicBlock *Pred : predecessors(&BB)) {
+        int count = 0;
+        if (more_than_one == -1)
+          more_than_one = 0;
+        //fprintf(stderr, " %p=>", Pred);
+        for (BasicBlock *Succ : successors(Pred)) {
+          //if (count > 0)
+          //  fprintf(stderr, "|");
+          if (Succ != NULL) count++;
+          //fprintf(stderr, "%p", Succ);
+        }
+        if (count > 1)
+          more_than_one = 1;
+      }
+      //fprintf(stderr, " == %d\n", more_than_one);
+      if (more_than_one != 1)
+        continue;
 
       ConstantInt *CurLoc = ConstantInt::get(Int32Ty, cur_loc);