[PATCH] D123216: [LoopSink] Use MemorySSA with legacy pass manager

[Nikita Popov via Phabricator via llvm-commits]

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LoopSink with the legacy pass manager still uses AST, because we can't compute MemorySSA conditionally. I think now that the legacy pass manager will be removed soon(TM) we don't need to care about compile-time impact here anymore. Additionally, since MemorySSA is no longer eagerly optimized, the impact is actually not that high anymore (0.2% regression: http://llvm-compile-time-tracker.com/compare.php?from=ed4e6e03981a37d54c4ac635b2bdb2c2fe8fec92&to=c3bfd875b637503adbeaccc59d19d8eb934bcfa7&stat=instructions)

This just makes legacy PM and new PM behavior line up -- as a followup I'll drop these options entirely and make MemorySSA use mandatory.


https://reviews.llvm.org/D123216

Files:
  llvm/lib/Transforms/Scalar/LoopSink.cpp


Index: llvm/lib/Transforms/Scalar/LoopSink.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopSink.cpp
+++ llvm/lib/Transforms/Scalar/LoopSink.cpp
@@ -70,7 +70,7 @@
     cl::desc("Enable MemorySSA for LoopSink in new pass manager"));
 
 static cl::opt<bool> EnableMSSAInLegacyLoopSink(
-    "enable-mssa-in-legacy-loop-sink", cl::Hidden, cl::init(false),
+    "enable-mssa-in-legacy-loop-sink", cl::Hidden, cl::init(true),
     cl::desc("Enable MemorySSA for LoopSink in legacy pass manager"));
 
 /// Return adjusted total frequency of \p BBs.


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