[llvm-bugs] [Bug 33111] New: KILL instruction has dangling memory operand

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=33111

            Bug ID: 33111
           Summary: KILL instruction has dangling memory operand
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Register Allocator
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 18483
  --> https://bugs.llvm.org/attachment.cgi?id=18483&action=edit
reduced testcase

bin/llc -mtriple=s390x-linux-gnu -mcpu=z13 -verify-regalloc -disable-cgp
-disable-machine-dce ./tc_miss_mayloadflag.ll

It seems that while changing opcode to KILL, there is a memory operand that
isn't removed:

144B    BB#4: derived from LLVM BB %CF369
            Predecessors according to CFG: BB#3
160B            CHIMux %vreg0, 0, %CC<imp-def>; GRX32Bit:%vreg0
176B            %vreg1<def,tied1> = LOCG %vreg1<undef,tied0>, %vreg5<undef>, 0,
14, 6, %CC<imp-use,kill>; mem:LD8[undef] GR64Bit:%vreg1 ADDR64Bit:%vreg5
192B            %vreg6<def> = LHIMux 0; GRX32Bit:%vreg6

->

# *** IR Dump After Simple Register Coalescing ***:

144B    BB#4: derived from LLVM BB %CF369
            Predecessors according to CFG: BB#3
160B            CHIMux %vreg0, 0, %CC<imp-def>; GRX32Bit:%vreg0
176B            KILL %CC<imp-use,kill>; mem:LD8[undef]
192B            %vreg6<def> = LHIMux 0; GRX32Bit:%vreg6

*** Bad machine code: Missing mayLoad flag ***
- function:    autogen_SD7792
- basic block: BB#4 CF369 (0x4f6b988) [144B;208B)
- instruction: 176B     KILL

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