[LLVM][CanonicalizeFreezeInLoops] fix duplicate removal

[Friedrich20]

No description provided.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Wei Tao (Friedrich20)

Changes

This PR fixes #74572 where the the freeze instruction could be found twice by the pass CanonicalizeFreezeInLoops, and then the compiling may crash in second removal since the instruction has already gone.

---

Full diff: https://github.com/llvm/llvm-project/pull/74714.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp (+7)

diff --git a/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp b/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
index fb4d828853772..af9dad143e2ed 100644
--- a/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
+++ b/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
@@ -151,11 +151,18 @@ bool CanonicalizeFreezeInLoopsImpl::run() {
       }
     }
 
+    bool Exist = false;
     auto Visit = [&](User *U) {
       if (auto *FI = dyn_cast<FreezeInst>(U)) {
+        for (const auto &Candidate : Candidates) {
+          auto *FI_cand = Candidate.FI;
+          Exist = (FI_cand == FI) ? true : Exist;
+        }
+        if (!Exist) {
         LLVM_DEBUG(dbgs() << "canonfr: found: " << *FI << "\n");
         Info.FI = FI;
         Candidates.push_back(Info);
+        }
       }
     };
     for_each(PHI.users(), Visit);

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 6a1badfed2dcd438d94a35cc4ab3b38c7cc06208 903262f32a67d7933ff7d240f6f3793b8a6609a3 -- llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp

View the diff from clang-format here.

diff --git a/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp b/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
index af9dad143e..ff1eb17e0c 100644
--- a/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
+++ b/llvm/lib/Transforms/Utils/CanonicalizeFreezeInLoops.cpp
@@ -159,9 +159,9 @@ bool CanonicalizeFreezeInLoopsImpl::run() {
           Exist = (FI_cand == FI) ? true : Exist;
         }
         if (!Exist) {
-        LLVM_DEBUG(dbgs() << "canonfr: found: " << *FI << "\n");
-        Info.FI = FI;
-        Candidates.push_back(Info);
+          LLVM_DEBUG(dbgs() << "canonfr: found: " << *FI << "\n");
+          Info.FI = FI;
+          Candidates.push_back(Info);
         }
       }
     };