From 95453fdfab3cd5a02f60887f95ba485dafb5938a Mon Sep 17 00:00:00 2001
From: Andy Ragusa <aragusa@cisco.com>
Date: Fri, 26 Apr 2024 15:09:12 -0700
Subject: [PATCH] blah

---
 clambcc/clambc-compiler.py             |   2 +-
 libclambcc/ClamBCRemovePointerPHIs.cpp | 121 +++++++++++++++++++++++++
 2 files changed, 122 insertions(+), 1 deletion(-)

diff --git a/clambcc/clambc-compiler.py b/clambcc/clambc-compiler.py
index fa630f4c87..f932065cee 100755
--- a/clambcc/clambc-compiler.py
+++ b/clambcc/clambc-compiler.py
@@ -577,7 +577,7 @@ def createInputSourceFile(clangLLVM: ClangLLVM, name: str, args: list, options:
         , 'clambc-rebuild'
         , 'verify'
 #        , 'clambc-remove-pointer-phis'
-        , 'verify'
+#        , 'verify'
         , 'clambc-trace'
         , 'verify'
         , 'clambc-outline-endianness-calls'
diff --git a/libclambcc/ClamBCRemovePointerPHIs.cpp b/libclambcc/ClamBCRemovePointerPHIs.cpp
index 05c398f7e1..1dce1c0183 100644
--- a/libclambcc/ClamBCRemovePointerPHIs.cpp
+++ b/libclambcc/ClamBCRemovePointerPHIs.cpp
@@ -185,6 +185,9 @@ class ClamBCRemovePointerPHIs : public PassInfoMixin<ClamBCRemovePointerPHIs>
             return false;
         }
 
+
+        DEBUG_VALUE(pn);
+
         IntegerType *pType = Type::getInt64Ty(pMod->getContext());
         Constant *zero     = ConstantInt::get(pType, 0);
         Value *initValue   = zero;
@@ -293,6 +296,118 @@ class ClamBCRemovePointerPHIs : public PassInfoMixin<ClamBCRemovePointerPHIs>
         return true;
     }
 
+    /*The idea here is that we get the insertion point for where our calculated value
+     * will be saved.  pInst is the value we want to save, so it will have to be*/
+    Instruction * getInsertionPoint(Instruction * pInst){
+        BasicBlock * pBB = pInst->getParent();
+        bool canBreak = false;
+        Instruction * pRet = nullptr;
+        for (auto i = pBB->begin(), e = pBB->end(); i != e; i++){
+            pRet = llvm::cast<Instruction>(i);
+            if (canBreak && (not llvm::isa<PHINode>(pRet))){
+                break;
+            }
+            if (pRet == pInst){
+                canBreak = true;
+            }
+        }
+        return pRet;
+    }
+
+    /* Load the value from our AllocaInst, and
+     * replace the PHINode everywhere it is used.*/
+    virtual void replaceUses(PHINode * pn, AllocaInst * pai){
+        std::vector<Instruction *> users;
+        for (auto i = pn->user_begin(), e = pn->user_end(); i != e; i++) {
+            if (Instruction *pUser = llvm::dyn_cast<Instruction>(*i)) {
+                users.push_back(pUser);
+            }
+        }
+
+        for (size_t i = 0; i < users.size(); i++) {
+            Instruction *pUser = users[i];
+            Instruction * insPt = nullptr;
+
+            if (PHINode * pnUser = llvm::dyn_cast<PHINode>(pUser)){
+                for (size_t j = 0; j < pnUser->getNumIncomingValues(); j++){
+                    if (pn == pnUser->getIncomingValue(j)){
+                        insPt = pnUser->getIncomingBlock(j)->getTerminator();
+                        break;
+                    }
+                }
+            } else {
+                insPt = pUser;
+            }
+
+            DEBUG_VALUE(pai);
+            DEBUG_VALUE(pai->getType());
+            DEBUG_VALUE(pUser);
+            DEBUG_VALUE(pUser->getType());
+
+            LoadInst * pli = new LoadInst(pn->getType(), pai, "ClamBCRemovePointerPHIs_load_", insPt);
+            for (size_t j = 0; j < pUser->getNumOperands(); j++){
+                if (pn == pUser->getOperand(j)){
+                    pUser->setOperand(j, pli);
+                    break;
+                }
+            }
+
+        }
+
+        }
+
+    bool handlePHI2(PHINode *pn)
+    {
+        if (not pn->getType()->isPointerTy()) {
+            return false;
+        }
+
+        Value *pBasePtr = findBasePointer(pn);
+        if (nullptr == pBasePtr) { /*No unique base pointer.*/
+            return false;
+        }
+
+        /* Create our storage variable in the first basic block,
+         * right before the branch instruction.*/
+        Function * pFunc = pn->getParent()->getParent();
+        BasicBlock * pEntry = llvm::cast<BasicBlock>(pFunc->begin());
+        Instruction * insPt = pEntry->getTerminator();
+        AllocaInst * pai = new AllocaInst(pn->getType(),
+                pFunc->getAddressSpace(), "ClamBCRemovePointerPHIs_", insPt);
+
+        DEBUG_VALUE(pn);
+        /* Go to all the locations that are incoming to our phi block, and store
+         * the value the phi is using as input in our alloca instruction.
+         */
+        for (size_t i = 0; i < pn->getNumIncomingValues(); i++) {
+            BasicBlock * pBB = pn->getIncomingBlock(i);
+#if 0
+            Instruction *incoming = llvm::dyn_cast<Instruction>(pn->getIncomingValue(i));
+            if (nullptr == incoming){
+                DEBUG_VALUE(pn);
+                DEBUG_VALUE(pn->getIncomingValue(i));
+                assert (0 && "HOW DID THIS HAPPEN?");
+            }
+
+            insPt = getInsertionPoint(incoming);
+            new StoreInst(incoming, pai, insPt);
+#else
+            insPt = pBB->getTerminator();
+            new StoreInst(pn->getIncomingValue(i), pai, insPt);
+#endif
+        }
+
+        replaceUses(pn, pai);
+        pn->eraseFromParent();
+
+
+
+        return true;
+
+    }
+
+
+
   public:
     ClamBCRemovePointerPHIs() {}
 
@@ -313,9 +428,15 @@ class ClamBCRemovePointerPHIs : public PassInfoMixin<ClamBCRemovePointerPHIs>
             for (size_t i = 0; i < phis.size(); i++) {
                 PHINode *pn = phis[i];
 
+#if 0
                 if (handlePHI(pn)) {
                     ret = true;
                 }
+#else
+                if (handlePHI2(pn)) {
+                    ret = true;
+                }
+#endif
             }
         }