[MachineOutliner] Count savings from outlining in bytes.
Counting the number of instructions is both unintuitive and inaccurate.
On AArch64, this only affects the generated remarks and certain rare
pseudo-instructions, but it will have a bigger impact on other targets.
Differential Revision: https://reviews.llvm.org/D46921
llvm-svn: 332685
diff --git a/llvm/lib/CodeGen/MachineOutliner.cpp b/llvm/lib/CodeGen/MachineOutliner.cpp
index afee909..be12b20 100644
--- a/llvm/lib/CodeGen/MachineOutliner.cpp
+++ b/llvm/lib/CodeGen/MachineOutliner.cpp
@@ -210,17 +210,22 @@
return getOccurrenceCount();
}
- /// Return the number of instructions it would take to outline this
+ /// Return the number of bytes it would take to outline this
/// function.
unsigned getOutliningCost() {
- return (OccurrenceCount * MInfo.CallOverhead) + Sequence.size() +
+ return (OccurrenceCount * MInfo.CallOverhead) + MInfo.SequenceSize +
MInfo.FrameOverhead;
}
+ /// Return the size in bytes of the unoutlined sequences.
+ unsigned getNotOutlinedCost() {
+ return OccurrenceCount * MInfo.SequenceSize;
+ }
+
/// Return the number of instructions that would be saved by outlining
/// this function.
unsigned getBenefit() {
- unsigned NotOutlinedCost = OccurrenceCount * Sequence.size();
+ unsigned NotOutlinedCost = getNotOutlinedCost();
unsigned OutlinedCost = getOutliningCost();
return (NotOutlinedCost < OutlinedCost) ? 0
: NotOutlinedCost - OutlinedCost;
@@ -1054,10 +1059,10 @@
R << "Did not outline " << NV("Length", StringLen) << " instructions"
<< " from " << NV("NumOccurrences", RepeatedSequenceLocs.size())
<< " locations."
- << " Instructions from outlining all occurrences ("
+ << " Bytes from outlining all occurrences ("
<< NV("OutliningCost", OF.getOutliningCost()) << ")"
- << " >= Unoutlined instruction count ("
- << NV("NotOutliningCost", StringLen * OF.getOccurrenceCount()) << ")"
+ << " >= Unoutlined instruction bytes ("
+ << NV("NotOutliningCost", OF.getNotOutlinedCost()) << ")"
<< " (Also found at: ";
// Tell the user the other places the candidate was found.
@@ -1378,7 +1383,7 @@
MachineOptimizationRemark R(DEBUG_TYPE, "OutlinedFunction",
MBB->findDebugLoc(MBB->begin()), MBB);
R << "Saved " << NV("OutliningBenefit", OF.getBenefit())
- << " instructions by "
+ << " bytes by "
<< "outlining " << NV("Length", OF.Sequence.size()) << " instructions "
<< "from " << NV("NumOccurrences", OF.getOccurrenceCount())
<< " locations. "