[llvm-branch-commits] [llvm] [AMDGPU] Use reverse iteration in CodeGenPrepare (PR #145484)

[Matt Arsenault via llvm-branch-commits]

================
@@ -285,28 +287,19 @@ bool AMDGPUCodeGenPrepareImpl::run() {
   BreakPhiNodesCache.clear();
   bool MadeChange = false;
 
-  Function::iterator NextBB;
-  for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; FI = NextBB) {
-    BasicBlock *BB = &*FI;
-    NextBB = std::next(FI);
-
-    BasicBlock::iterator Next;
-    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;
-         I = Next) {
-      Next = std::next(I);
-
-      MadeChange |= visit(*I);
-
-      if (Next != E) { // Control flow changed
-        BasicBlock *NextInstBB = Next->getParent();
-        if (NextInstBB != BB) {
-          BB = NextInstBB;
-          E = BB->end();
-          FE = F.end();
-        }
-      }
+  for (BasicBlock &BB : reverse(F)) {
+    for (Instruction &I : make_early_inc_range(reverse(BB))) {
+      if (!DeadVals.contains(&I))
+        MadeChange |= visit(I);
     }
   }
+
+  while (!DeadVals.empty()) {
+    RecursivelyDeleteTriviallyDeadInstructions(
+        DeadVals.pop_back_val(), TLI, /*MSSAU*/ nullptr,
----------------
arsenm wrote:

```suggestion
        DeadVals.pop_back_val(), TLI, /*MSSAU=*/ nullptr,
```

https://github.com/llvm/llvm-project/pull/145484