Enzyme fix for scev usage

Author: ZuseZ4

enzyme/Enzyme/GradientUtils.cpp

@@ -8552,15 +8552,22 @@ bool GradientUtils::getContext(llvm::BasicBlock *BB, LoopContext &lc) {
 void GradientUtils::forceAugmentedReturns() {
   assert(TR.getFunction() == oldFunc);
 
-  for (BasicBlock &oBB : *oldFunc) {
-    // Don't create derivatives for code that results in termination
-    if (notForAnalysis.find(&oBB) != notForAnalysis.end())
+  // Pass 1: create BB-level contexts for the whole loop/function
+  for (BasicBlock &oBBRef : *oldFunc) {
+    BasicBlock *oBB = &oBBRef;
+    if (notForAnalysis.find(oBB) != notForAnalysis.end())
       continue;
+    LoopContext LC;
+    getContext(cast<BasicBlock>(getNewFromOriginal(oBB)), LC);
+  }
 
-    LoopContext loopContext;
-    getContext(cast<BasicBlock>(getNewFromOriginal(&oBB)), loopContext);
+  // Pass 2: instruction processing (unchanged semantics)
+  for (BasicBlock &oBBRef : *oldFunc) {
+    BasicBlock *oBB = &oBBRef;
+    if (notForAnalysis.find(oBB) != notForAnalysis.end())
+      continue;
 
-    for (Instruction &I : oBB) {
+    for (Instruction &I : *oBB) {
       Instruction *inst = &I;
 
       if (inst->getType()->isEmptyTy() || inst->getType()->isVoidTy())