[llvm-bugs] [Bug 47397] New: [NPM] -time-passes does not aggregate time spent per pass

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https://bugs.llvm.org/show_bug.cgi?id=47397

            Bug ID: 47397
           Summary: [NPM] -time-passes  does not aggregate time spent per
                    pass
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: florian_hahn at apple.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

It looks like `-time-passes` behaves differently under the new & legacy pass
manager.

The legacy pass manager shows a single entry for the time spent in a pass for
all functions, whereas the new pass manager shows separate entries for each
function a pass runs on.

Running `bin/opt -aa-pipeline=basic-aa -passes='dse' foo.ll -time-passes 2>&1 
| grep DSEPass` on the IR below will show 2 entries for DSE, one for each
function.

Running `opt -dse foo.ll -time-passes 2>&1  | grep 'Dead Store'`  shows a
single entry, containing the run times for DSE on both functions.

Personally I find the behavior of the legacy pass manager more useful, because
on files with many functions the output with the new pass manager becomes
un-manageable.


foo.ll:

define void @test1(i32* %Q, i32* %P) {
  ret void
}

define void @test2(i32* %Q, i32* %P) {
  ret void
}

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