`-Wuninitialized` warnings in `llvm/lib/Target/Hexagon/`

[firewave]

In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.cpp:55:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized]
   75 |     UseQueueType() : Uses(Dist) {}
      |                           ^~~~
In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonBitSimplify.cpp:9:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized]
   75 |     UseQueueType() : Uses(Dist) {}
      |                           ^~~~
In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonBitTracker.h:12,
                 from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonBitTracker.cpp:9:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized]
   75 |     UseQueueType() : Uses(Dist) {}
      |                           ^~~~
In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonGenInsert.cpp:9:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’:
/home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized]
   75 |     UseQueueType() : Uses(Dist) {}
      |                           ^~~~

I am using gcc (GCC) 14.2.1 20240910 on Manjaro Linux.

[llvmbot]

@llvm/issue-subscribers-backend-hexagon

Author: Oliver Stöneberg (firewave)

``` In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.cpp:55: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized] 75 | UseQueueType() : Uses(Dist) {} | ^~~~ In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonBitSimplify.cpp:9: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized] 75 | UseQueueType() : Uses(Dist) {} | ^~~~ In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonBitTracker.h:12, from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonBitTracker.cpp:9: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized] 75 | UseQueueType() : Uses(Dist) {} | ^~~~ In file included from /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/HexagonGenInsert.cpp:9: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h: In constructor ‘llvm::BitTracker::UseQueueType::UseQueueType()’: /home/user/CLionProjects/llvm-project/llvm/lib/Target/Hexagon/BitTracker.h:75:27: warning: member ‘llvm::BitTracker::UseQueueType::Dist’ is used uninitialized [-Wuninitialized] 75 | UseQueueType() : Uses(Dist) {} | ^~~~ ```

I am using gcc (GCC) 14.2.1 20240910 on Manjaro Linux.

[androm3da]

@firewave can you check if this change fixes it?

diff --git a/llvm/lib/Target/Hexagon/BitTracker.h b/llvm/lib/Target/Hexagon/BitTracker.h
index 08c0359a4b7f..d2a8c98369a0 100644
--- a/llvm/lib/Target/Hexagon/BitTracker.h
+++ b/llvm/lib/Target/Hexagon/BitTracker.h
@@ -72,7 +72,7 @@ private:
   // Priority queue of instructions using modified registers, ordered by
   // their relative position in a basic block.
   struct UseQueueType {
-    UseQueueType() : Uses(Dist) {}
+    UseQueueType() : Dist(), Uses(Dist) {}
 
     unsigned size() const {
       return Uses.size();
@@ -100,9 +100,9 @@ private:
       bool operator()(const MachineInstr *MI, const MachineInstr *MJ) const;
       DenseMap<const MachineInstr*,unsigned> &Dist;
     };
-    std::priority_queue<MachineInstr*, std::vector<MachineInstr*>, Cmp> Uses;
     DenseSet<const MachineInstr*> Set; // Set to avoid adding duplicate entries.
     DenseMap<const MachineInstr*,unsigned> Dist;
+    std::priority_queue<MachineInstr*, std::vector<MachineInstr*>, Cmp> Uses;
   };
 
   void reset();

[androm3da]

I tried it on 12.3.0-1ubuntu1~22.04 and it seemed to work.

[firewave]

@firewave can you check if this change fixes it?

I can confirm that this fixes the warning.