[llvm] [LV] Add cross-part load overlap heuristic for interleaving (PR #214500)

[Sergey Shcherbinin via llvm-commits]

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@@ -300,6 +302,23 @@ static cl::opt<bool> EnableLoadStoreRuntimeInterleave(
     cl::desc(
         "Enable runtime interleaving until load/store ports are saturated"));
 
+/// Enable cross-part load-overlap analysis during IC selection.
+static cl::opt<bool> EnableInterleaveCSE(
+    "enable-interleave-cse", cl::init(false), cl::Hidden,
+    cl::desc("Raise heuristic IC=1 to IC=2 when exact cross-part load overlap "
+             "predicts a downstream saving"));
+
+/// Minimum percentage of the modeled UF=2 body predicted to be saved.
+static cl::opt<unsigned> InterleaveCSEMinSavingPct(
+    "interleave-cse-min-pct", cl::init(5), cl::Hidden,
+    cl::desc("Minimum predicted downstream load saving as a percentage of the "
+             "modeled UF=2 vector loop body"));
+
+/// Minimum number of exact load overlaps required to request IC=2.
+static cl::opt<unsigned> InterleaveCSEMinOpportunities(
+    "interleave-cse-min-ops", cl::init(2), cl::Hidden,
+    cl::desc("Minimum number of exact cross-part load-overlap opportunities"));
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SergeyShch01 wrote:

Agreed, all three were not needed. I removed the minimum-opportunity knob. The updated patch keeps only the opt-in enable flag and one profitability threshold based on predicted saved load cost relative to the modeled UF=2 loop cost. 

https://github.com/llvm/llvm-project/pull/214500