[llvm-bugs] [Bug 28990] New: Incorrect sample profile when braces omitted

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=28990

            Bug ID: 28990
           Summary: Incorrect sample profile when braces omitted
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: dcallahan at fb.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 16959
  --> https://llvm.org/bugs/attachment.cgi?id=16959&action=edit
script to demonstrate

Attached are two source variables, bug1.cc and bug2.cc which differ only in the
placement of braces around a then-statement. When these braces are omitted, a
profile-based sample is incorrect while it is correct when they are present.

Reproduction steps are in bug1.sh
create_llvm_prof is available at https://github.com/google/autofdo

The incorrect sample derived from bug1.cc (from llvm-profdata show) is: 

Function: _Z8clampSumPdidd: 100803968, 0, 13 sampled lines
Samples collected in the function's body {
  0: 0
  1: 0
  2.1: 908152
  2.2: 908138
  3: 908139
  4: 0
  5: 908146
  6: 908142
  7: 908150
  9: 908149
  10: 908146
  11: 908138
  13: 4
}

while the correct sample derived from bug2.cc is 

Function: _Z8clampSumPdidd: 101434538, 1, 14 sampled lines
Samples collected in the function's body {
  0: 1
  1: 1
  2.1: 913831
  2.2: 913817
  3: 913818
  4: 0
  5: 913830
  6: 913826
  7: 0
  8: 913834
  9: 913831
  10: 913827
  11: 913821
  13: 1
}

where the key differences is the value for relative line 7, it should be 0.

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