From 0769f5ca156045986654ca3209f4c7183716d483 Mon Sep 17 00:00:00 2001
From: Tony Tao <tonytao@ca.ibm.com>
Date: Mon, 7 Apr 2025 10:37:14 -0400
Subject: [PATCH 1/5] Add check for INIT_UNDEF in getInstSizeInBytes

---
 llvm/include/llvm/CodeGen/MachineInstr.h      | 1 +
 llvm/lib/Target/SystemZ/SystemZLongBranch.cpp | 1 +
 2 files changed, 2 insertions(+)

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 ||

From 51066169099b5e57c35c05538db83eeea8dc5dc5 Mon Sep 17 00:00:00 2001
From: Tony Tao <tonytao@ca.ibm.com>
Date: Mon, 7 Apr 2025 10:54:59 -0400
Subject: [PATCH 2/5] syntax fix

---
 llvm/include/llvm/CodeGen/MachineInstr.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index cd7b3055ad722..f68fd924e014f 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -1408,8 +1408,8 @@ class MachineInstr
            getOpcode() == TargetOpcode::G_PHI;
   }
   bool isKill() const { return getOpcode() == TargetOpcode::KILL; }
-  bool isImplicitDef() const { return getOpcode()==TargetOpcode::IMPLICIT_DEF; }
-  bool isInitUndef() const { return getOpcode()==TargetOpcode::INIT_UNDEF; }
+  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;

From c080f6bdf1a0e1401d53e064cb242735f8ef9d44 Mon Sep 17 00:00:00 2001
From: Tony Tao <tonytao@ca.ibm.com>
Date: Mon, 7 Apr 2025 10:58:23 -0400
Subject: [PATCH 3/5] undo syntax fix

---
 llvm/include/llvm/CodeGen/MachineInstr.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index f68fd924e014f..5d4ce8431a9c7 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -1408,7 +1408,7 @@ class MachineInstr
            getOpcode() == TargetOpcode::G_PHI;
   }
   bool isKill() const { return getOpcode() == TargetOpcode::KILL; }
-  bool isImplicitDef() const { return getOpcode() == TargetOpcode::IMPLICIT_DEF; }
+  bool isImplicitDef() const { return getOpcode()==TargetOpcode::IMPLICIT_DEF; }
   bool isInitUndef() const { return getOpcode() == TargetOpcode::INIT_UNDEF; }
   bool isInlineAsm() const {
     return getOpcode() == TargetOpcode::INLINEASM ||

From 53b0095f3b761ed99b52fdffde3db5a3f1d4a44b Mon Sep 17 00:00:00 2001
From: Tony Tao <tonytao@ca.ibm.com>
Date: Mon, 7 Apr 2025 13:03:13 -0400
Subject: [PATCH 4/5] remove accessor

---
 llvm/include/llvm/CodeGen/MachineInstr.h      | 1 -
 llvm/lib/Target/SystemZ/SystemZLongBranch.cpp | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index 5d4ce8431a9c7..102b1eb07358e 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -1409,7 +1409,6 @@ 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 f0f33c960d822..8103bfe5f4f12 100644
--- a/llvm/lib/Target/SystemZ/SystemZLongBranch.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZLongBranch.cpp
@@ -218,7 +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() ||
+          MI.getOpcode() == TargetOpcode::INIT_UNDEF ||
           // These have a size that may be zero:
           MI.isInlineAsm() || MI.getOpcode() == SystemZ::STACKMAP ||
           MI.getOpcode() == SystemZ::PATCHPOINT ||

From 85ab496fa52b7c7e0b2e0a38c37fc6db723deff2 Mon Sep 17 00:00:00 2001
From: Tony Tao <tonytao@ca.ibm.com>
Date: Tue, 8 Apr 2025 15:05:09 -0400
Subject: [PATCH 5/5] add mir test

---
 llvm/test/CodeGen/SystemZ/init-undef.mir | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 llvm/test/CodeGen/SystemZ/init-undef.mir

diff --git a/llvm/test/CodeGen/SystemZ/init-undef.mir b/llvm/test/CodeGen/SystemZ/init-undef.mir
new file mode 100644
index 0000000000000..101dc6ebf8fd5
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/init-undef.mir
@@ -0,0 +1,17 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# REQUIRES: asserts
+# RUN: llc -run-pass systemz-long-branch -mtriple=s390x-ibm-zos -o - %s | FileCheck %s
+
+# Makes sure INIT_UNDEF does not crash the compiler in systemz-long-branch
+---
+name: func0
+body: |
+  bb.0.entry:
+    ; CHECK-LABEL: name: func0
+    ; CHECK: renamable $r0l = INIT_UNDEF
+    ; CHECK-NEXT: renamable $r3d = LGFR killed renamable $r0l
+    ; CHECK-NEXT: frame-destroy Return_XPLINK implicit $r3d
+    renamable $r0l = INIT_UNDEF
+    renamable $r3d = LGFR killed renamable $r0l
+    frame-destroy Return_XPLINK implicit $r3d
+...