[llvm] [MachineVerifier] Allow KILL MI with dangling MMO in MachineVerifier. (PR #114407)

[Jonas Paulsson via llvm-commits]

https://github.com/JonPsson1 updated https://github.com/llvm/llvm-project/pull/114407

>From c5df1fd8db52905a5af2cb02716e4d3300ef2a72 Mon Sep 17 00:00:00 2001
From: Jonas Paulsson <paulson1 at linux.ibm.com>
Date: Thu, 31 Oct 2024 14:48:31 +0100
Subject: [PATCH 1/2] Allow KILL MI with dangling MMO in MachineVerifier.

---
 llvm/lib/CodeGen/MachineVerifier.cpp          |  2 +-
 .../CodeGen/SystemZ/machine-ver-kill-memop.ll | 30 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll

diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index e2c09fe25d55cd..cc5acccdc8df66 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -2271,7 +2271,7 @@ void MachineVerifier::visitMachineInstrBefore(const MachineInstr *MI) {
 
   // Check the MachineMemOperands for basic consistency.
   for (MachineMemOperand *Op : MI->memoperands()) {
-    if (Op->isLoad() && !MI->mayLoad())
+    if (Op->isLoad() && (!MI->mayLoad() && !MI->isKill()))
       report("Missing mayLoad flag", MI);
     if (Op->isStore() && !MI->mayStore())
       report("Missing mayStore flag", MI);
diff --git a/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll b/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll
new file mode 100644
index 00000000000000..b3cbc332f473a3
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll
@@ -0,0 +1,30 @@
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z16 -disable-machine-dce \
+; RUN:   -verify-machineinstrs -O3
+;
+; Test that this passes the verifier even though a KILL instruction with a
+; dangling memory operand emerges.
+
+define void @fun(ptr %Src, ptr %Dst) {
+  br label %2
+
+2:
+  %3 = load i32, ptr %Src, align 4
+  %4 = freeze i32 %3
+  %5 = icmp eq i32 %4, 0
+  %6 = load i32, ptr poison, align 4
+  %7 = select i1 %5, i32 0, i32 %6
+  %8 = load i32, ptr %Src, align 4
+  %9 = freeze i32 %8
+  %10 = icmp eq i32 %9, 0
+  %11 = load i32, ptr poison, align 4
+  %12 = select i1 %10, i32 0, i32 %11
+  br label %13
+
+13:
+  %14 = phi i32 [ %12, %13 ], [ %7, %2 ]
+  %15 = icmp slt i32 %14, 5
+  %16 = zext i1 %15 to i64
+  %17 = xor i64 poison, %16
+  store i64 %17, ptr %Dst, align 8
+  br label %13
+}

>From f03ba98cae95ae64800ffc8d4d1de555375504b3 Mon Sep 17 00:00:00 2001
From: Jonas Paulsson <paulson1 at linux.ibm.com>
Date: Mon, 4 Nov 2024 15:19:42 -0600
Subject: [PATCH 2/2] Remove the MMO instead in LiveRangeEdit.

---
 llvm/lib/CodeGen/LiveRangeEdit.cpp                  | 1 +
 llvm/lib/CodeGen/MachineVerifier.cpp                | 2 +-
 llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll | 4 ++--
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index c3c581d42236e4..7b630e88b2a604 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -385,6 +385,7 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
         continue;
       MI->removeOperand(i-1);
     }
+    MI->dropMemRefs(*MI->getMF());
     LLVM_DEBUG(dbgs() << "Converted physregs to:\t" << *MI);
   } else {
     // If the dest of MI is an original reg and MI is reMaterializable,
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index cc5acccdc8df66..e2c09fe25d55cd 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -2271,7 +2271,7 @@ void MachineVerifier::visitMachineInstrBefore(const MachineInstr *MI) {
 
   // Check the MachineMemOperands for basic consistency.
   for (MachineMemOperand *Op : MI->memoperands()) {
-    if (Op->isLoad() && (!MI->mayLoad() && !MI->isKill()))
+    if (Op->isLoad() && !MI->mayLoad())
       report("Missing mayLoad flag", MI);
     if (Op->isStore() && !MI->mayStore())
       report("Missing mayStore flag", MI);
diff --git a/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll b/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll
index b3cbc332f473a3..793fd3908b9f8a 100644
--- a/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll
+++ b/llvm/test/CodeGen/SystemZ/machine-ver-kill-memop.ll
@@ -1,8 +1,8 @@
 ; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z16 -disable-machine-dce \
 ; RUN:   -verify-machineinstrs -O3
 ;
-; Test that this passes the verifier even though a KILL instruction with a
-; dangling memory operand emerges.
+; Test that the MemoryOperand of the produced KILL instruction is removed
+; and as a result the machine verifier succeeds.
 
 define void @fun(ptr %Src, ptr %Dst) {
   br label %2