Add abs to known integral values interpretation (rust-lang#621)

Author: wsmoses

enzyme/Enzyme/GradientUtils.h

@@ -2289,17 +2289,14 @@ class DiffeGradientUtils : public GradientUtils {
     assert(ptr);
     if (OrigOffset) {
       Value *newOffset = lookupM(getNewFromOriginal(OrigOffset), BuilderM);
-#if LLVM_VERSION_MAJOR > 7
       auto rule = [&](Value *ptr) {
+#if LLVM_VERSION_MAJOR > 7
         return BuilderM.CreateGEP(ptr->getType()->getPointerElementType(), ptr,
                                   newOffset);
-      };
 #else
-      auto rule = [&](Value *ptr) {
-        return BuilderM.CreateGEP(
-            ptr, lookupM(getNewFromOriginal(OrigOffset), BuilderM));
-      };
+        return BuilderM.CreateGEP(ptr, newOffset);
 #endif
+      };
       ptr = applyChainRule(diffType, BuilderM, rule, ptr);
     }
 

enzyme/Enzyme/TypeAnalysis/TypeAnalysis.cpp

@@ -4349,7 +4349,13 @@ FnTypeInfo::knownIntegralValues(llvm::Value *val, const DominatorTree &DT,
   };
   if (auto II = dyn_cast<IntrinsicInst>(val)) {
     switch (II->getIntrinsicID()) {
-
+#if LLVM_VERSION_MAJOR >= 12
+    case Intrinsic::abs:
+      for (auto val :
+           knownIntegralValues(II->getArgOperand(0), DT, intseen, SE))
+        insert(abs(val));
+      break;
+#endif
     case Intrinsic::nvvm_read_ptx_sreg_tid_x:
     case Intrinsic::nvvm_read_ptx_sreg_tid_y:
     case Intrinsic::nvvm_read_ptx_sreg_tid_z: