[llvm] [GVN] MemorySSA for GVN: embed the memory state in symbolic expressions (PR #123218)

[Antonio Frighetto via llvm-commits]

================
@@ -2294,15 +2350,39 @@ bool GVNPass::ValueTable::areCallValsEqual(uint32_t Num, uint32_t NewNum,
 uint32_t GVNPass::ValueTable::phiTranslateImpl(const BasicBlock *Pred,
                                                const BasicBlock *PhiBlock,
                                                uint32_t Num, GVNPass &Gvn) {
+  // See if we can refine the value number by looking at the PN incoming value
+  // for the given predecessor.
   if (PHINode *PN = NumberingPhi[Num]) {
-    for (unsigned i = 0; i != PN->getNumIncomingValues(); ++i) {
-      if (PN->getParent() == PhiBlock && PN->getIncomingBlock(i) == Pred)
-        if (uint32_t TransVal = lookup(PN->getIncomingValue(i), false))
-          return TransVal;
-    }
+    if (PN->getParent() == PhiBlock)
----------------
antoniofrighetto wrote:

Just hoisted the check out of the loop, can also drop as not strictly related to the patch.

https://github.com/llvm/llvm-project/pull/123218