[llvm] [LoopUnroll] Remove unused lifetime marker pairs (PR #106858)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw created https://github.com/llvm/llvm-project/pull/106858

None

>From f12d7f3efd2bd699880425e094cf07b414228c5e Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Sat, 31 Aug 2024 23:57:14 +0800
Subject: [PATCH] [LoopUnroll] Remove unused lifetime marker pairs

---
 llvm/lib/Transforms/Utils/LoopUnroll.cpp | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index a0406111ecbf3b..9e601215db55fa 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -375,7 +375,11 @@ void llvm::simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
   // At this point, the code is well formed.  Perform constprop, instsimplify,
   // and dce.
   const DataLayout &DL = L->getHeader()->getDataLayout();
+  Function *F = L->getHeader()->getParent();
   SmallVector<WeakTrackingVH, 16> DeadInsts;
+  bool DoNotOptimizeLifetimeMarkers = F->hasFnAttribute(Attribute::SanitizeAddress) ||
+        F->hasFnAttribute(Attribute::SanitizeMemory) ||
+        F->hasFnAttribute(Attribute::SanitizeHWAddress);
   for (BasicBlock *BB : L->getBlocks()) {
     // Remove repeated debug instructions after loop unrolling.
     if (BB->getParent()->getSubprogram())
@@ -387,6 +391,20 @@ void llvm::simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
           Inst.replaceAllUsesWith(V);
       if (isInstructionTriviallyDead(&Inst))
         DeadInsts.emplace_back(&Inst);
+      if (!DoNotOptimizeLifetimeMarkers)
+      if (auto *II = dyn_cast<IntrinsicInst>(&Inst)) {
+        if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
+          if (auto *PrevII = dyn_cast_or_null<IntrinsicInst>(II->getPrevNode())) 
+            if (PrevII->getIntrinsicID() == Intrinsic::lifetime_end) {
+              if (PrevII->getArgOperand(0) == II->getArgOperand(0) && 
+                  PrevII->getArgOperand(1) == II->getArgOperand(1)) {
+                PrevII->eraseFromParent();
+                II->eraseFromParent();
+                continue;
+              }
+          }
+        }
+      }
 
       // Fold ((add X, C1), C2) to (add X, C1+C2). This is very common in
       // unrolled loops, and handling this early allows following code to