[PATCH] D134641: [AMDGPU][Backend] Fix user-after-free in AMDGPUReleaseVGPRs::isLastVGPRUseVMEMStore

[Juan Manuel Martinez Caamaño via Phabricator via llvm-commits]

jmmartinez created this revision.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134641

Files:
  llvm/lib/Target/AMDGPU/AMDGPUReleaseVGPRs.cpp


Index: llvm/lib/Target/AMDGPU/AMDGPUReleaseVGPRs.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUReleaseVGPRs.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUReleaseVGPRs.cpp
@@ -57,7 +57,7 @@
     // false in case we have a cycle.
     BlockVMEMStoreType::iterator It;
     bool Inserted;
-    std::tie(It, Inserted) = BlockVMEMStore.insert({&MBB, false});
+    std::tie(It, Inserted) = BlockVMEMStore.try_emplace(&MBB, false);
     bool &CacheEntry = It->second;
     if (!Inserted)
       return CacheEntry;
@@ -76,6 +76,8 @@
 
     // Recursive call into parent blocks. Look into predecessors if there is no
     // vgpr used in this block.
+    // The iterator is not invalidated by the recursive calls since we grew the
+    // dictionary to hold all the entries in advance
     return CacheEntry = llvm::any_of(MBB.predecessors(),
                                      [this](MachineBasicBlock *Parent) {
                                        return isLastVGPRUseVMEMStore(*Parent);
@@ -120,6 +122,9 @@
     SII = ST.getInstrInfo();
     TRI = ST.getRegisterInfo();
 
+    // we grow BlockVMEMStore to prevent the invalidation of its iterators
+    BlockVMEMStore.grow(MF.size());
+
     bool Changed = false;
     for (auto &MBB : MF) {
       Changed |= runOnMachineBasicBlock(MBB);


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