[llvm] [GlobalIsel] Combine freeze (PR #93239)

[Dhruv Chawla via llvm-commits]

Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>,
Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>,
Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>,
Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/93239 at github.com>


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@@ -1745,18 +1778,55 @@ static bool canCreateUndefOrPoison(Register Reg, const MachineRegisterInfo &MRI,
                                    UndefPoisonKind Kind) {
   MachineInstr *RegDef = MRI.getVRegDef(Reg);
 
-  if (auto *GMI = dyn_cast<GenericMachineInstr>(RegDef)) {
-    if (ConsiderFlagsAndMetadata && includesPoison(Kind) &&
-        GMI->hasPoisonGeneratingFlags())
-      return true;
-  } else {
-    // Conservatively return true.
-    return true;
-  }
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dc03-work wrote:

Are regular `MachineInstr`s not capable of generating undef or poison?

https://github.com/llvm/llvm-project/pull/93239