MachineCopyPropagation: Do not remove copies preserved by regmask

llvm/lib/CodeGen/MachineCopyPropagation.cpp

@@ -1018,18 +1018,30 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
           continue;
         }
 
-        LLVM_DEBUG(dbgs() << "MCP: Removing copy due to regmask clobbering: ";
-                   MaybeDead->dump());
-
         // Invalidate all entries in the copy map which are not preserved by
         // this register mask.
-        for (unsigned RegUnit : TRI->regunits(Reg))
+        bool MIRefedinCopyInfo = false;
+        for (unsigned RegUnit : TRI->regunits(Reg)) {
           if (!PreservedRegUnits.test(RegUnit))
             Tracker.clobberRegUnit(RegUnit, *TRI, *TII, UseCopyInstr);
+          else {
+            if (MaybeDead == Tracker.findCopyForUnit(RegUnit, *TRI)) {
+              MIRefedinCopyInfo = true;
+            }
+          }
+        }
 
         // erase() will return the next valid iterator pointing to the next
         // element after the erased one.
         DI = MaybeDeadCopies.erase(DI);
+
+        // Preserved by RegMask, DO NOT remove copy
+        if (MIRefedinCopyInfo)
+          continue;
+
+        LLVM_DEBUG(dbgs() << "MCP: Removing copy due to regmask clobbering: "
+                          << *MaybeDead);
+
         MaybeDead->eraseFromParent();
         Changed = true;
         ++NumDeletes;

llvm/test/CodeGen/MIR/X86/pr126107.mir

@@ -0,0 +1,17 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -o - %s -mtriple=x86_64-- -run-pass=machine-cp | FileCheck %s
+
+---
+name:            main
+body:             |
+ bb.0.entry:
+    liveins: $ymm7
+    ; CHECK-LABEL: name: main
+    ; CHECK: liveins: $ymm7
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: renamable $ymm6 = COPY killed renamable $ymm7
+    ; CHECK-NEXT: CALL64r killed renamable $rax, csr_64_mostregs
+    ; CHECK-NEXT: renamable $ymm6 = VPADDWZ256rr $ymm6, $ymm6
+       renamable $ymm6 = COPY killed renamable $ymm7
+       CALL64r killed renamable $rax, csr_64_mostregs
+       renamable $ymm6 = VPADDWZ256rr $ymm6, $ymm6