[PATCH] D71027: Support repeated machine outlining

[Jessica Paquette via Phabricator via llvm-commits]

paquette added inline comments.


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Comment at: llvm/lib/CodeGen/MachineOutliner.cpp:1510-1512
+  unsigned NumRepeats = NumRepeat;
+  if (NumRepeats < 1)
+    NumRepeats = 1;
----------------
I think that allowing the number of repeats to be 0 is unintuitive.

Would it be possible to output an error when the number of repeats is less than 1 instead of silently changing it?



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Comment at: llvm/lib/CodeGen/MachineOutliner.cpp:1515-1517
+  for (unsigned I = 0; I < NumRepeats; I++) {
+    if (!runOnceOnModule(M, I))
+      return Changed;
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Can you add some debug output here that says why the outliner stopped running?

E.g.

- "Stopped outlining because `I >= NumRepeats`"
- "Stopped outlining at iteration `I` because no changes were found"

This debug output could then be used in a separate testcase showing that repeated outlining terminates as expected.


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Comment at: llvm/test/CodeGen/AArch64/machine-outliner-iterative.mir:65-71
+    %tmp4 = alloca [24 x i8], align 8
+    %tmp101 = getelementptr inbounds %10, %10* %tmp11, i64 0, i32 1
+    %tmp103 = bitcast %6* %tmp101 to i8*
+    call void @foo(i8* nonnull %tmp103, [24 x i8]* nonnull %tmp4, i64 33, i8* null)
+    %tmp1042 = bitcast %2* %tmp38 to %0*
+    call void @widget(%0* %tmp1042)
+    ret void
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The IR instructions inside each of the IR functions here should not be necessary.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71027/new/

https://reviews.llvm.org/D71027