compcov int fix

docs/Changelog.md

@@ -13,6 +13,7 @@
   * afl-cc:
     - re-enable i386 support that was accidently disabled
     - fixes for LTO and outdated afl-gcc mode
+    - fix COMPCOV split compare for old LLVMs
     - ensure shared memory variables are visible in weird build setups
   * afl-cmin
     - work with input files that have a space

instrumentation/split-compares-pass.so.cc

@@ -1778,7 +1778,13 @@ bool SplitComparesTransform::runOnModule(Module &M) {
 
             auto op0 = CI->getOperand(0);
             auto op1 = CI->getOperand(1);
+            // has to valid operands
             if (!op0 || !op1) { continue; }
+            // has exactly one constant and one variable
+            int constants = 0;
+            if (dyn_cast<ConstantInt>(op0)) { ++constants; }
+            if (dyn_cast<ConstantInt>(op1)) { ++constants; }
+            if (constants != 1) { continue; }
 
             auto iTy1 = dyn_cast<IntegerType>(op0->getType());
             if (iTy1 && isa<IntegerType>(op1->getType())) {