[llvm] [SystemZ] Add check for INIT_UNDEF in getInstSizeInBytes (PR #134661)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-systemz

Author: None (tltao)

<details>
<summary>Changes</summary>

Due to some optimization changes, INIT_UNDEF is making its way to `getInstSizeInBytes` in `llvm/lib/Target/SystemZ/SystemZLongBranch.cpp` but we do not have an exception there in the assert. Since INIT_UNDEF is described as being similar to IMPLICIT_DEF and there is a check for IMPLICIT_DEF, it seems logical to also add a check for INIT_UNDEF.

---
Full diff: https://github.com/llvm/llvm-project/pull/134661.diff


2 Files Affected:

- (modified) llvm/include/llvm/CodeGen/MachineInstr.h (+1) 
- (modified) llvm/lib/Target/SystemZ/SystemZLongBranch.cpp (+1) 


``````````diff
diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index 102b1eb07358e..cd7b3055ad722 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -1409,6 +1409,7 @@ class MachineInstr
   }
   bool isKill() const { return getOpcode() == TargetOpcode::KILL; }
   bool isImplicitDef() const { return getOpcode()==TargetOpcode::IMPLICIT_DEF; }
+  bool isInitUndef() const { return getOpcode()==TargetOpcode::INIT_UNDEF; }
   bool isInlineAsm() const {
     return getOpcode() == TargetOpcode::INLINEASM ||
            getOpcode() == TargetOpcode::INLINEASM_BR;
diff --git a/llvm/lib/Target/SystemZ/SystemZLongBranch.cpp b/llvm/lib/Target/SystemZ/SystemZLongBranch.cpp
index f19b932f3c731..f0f33c960d822 100644
--- a/llvm/lib/Target/SystemZ/SystemZLongBranch.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZLongBranch.cpp
@@ -218,6 +218,7 @@ static unsigned getInstSizeInBytes(const MachineInstr &MI,
           // These do not have a size:
           MI.isDebugOrPseudoInstr() || MI.isPosition() || MI.isKill() ||
           MI.isImplicitDef() || MI.getOpcode() == TargetOpcode::MEMBARRIER ||
+          MI.isInitUndef() ||
           // These have a size that may be zero:
           MI.isInlineAsm() || MI.getOpcode() == SystemZ::STACKMAP ||
           MI.getOpcode() == SystemZ::PATCHPOINT ||

``````````

</details>


https://github.com/llvm/llvm-project/pull/134661