[llvm-bugs] [Bug 40573] New: [Debuginfo] @llvm.dbg.value changes behaviour of "Speculatively execute instructions"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=40573

            Bug ID: 40573
           Summary: [Debuginfo] @llvm.dbg.value changes behaviour of
                    "Speculatively execute instructions"
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 21421
  --> https://bugs.llvm.org/attachment.cgi?id=21421&action=edit
reduced testcase

Without the @llvm.dbg instruction in the test case, the fdiv instruction is
moved up in the CFG by 

bin/opt -mtriple=systemz-unknown -mcpu=z13 -S tc_speculexe.ll
-speculative-execution

I suspect that this is also (as in bug 40564) related to counting instructions
in the block on the line

     if (NotHoisted.size() > SpecExecMaxNotHoisted)

in SpeculativeExecution.cpp

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