[PATCH] D56356: [WebAssembly] Move CFG-changing passes before RegStackify

[Heejin Ahn via Phabricator via llvm-commits]

aheejin created this revision.
aheejin added reviewers: dschuff, kripken, sunfish.
Herald added subscribers: llvm-commits, jgravelle-google, sbc100.

FixIrreducibleControlFlow and LateEHPrepare both possibly modify CFG and
create new registers. There seems to be no reason these passes go after
register-related optimization passes (PrepareForLiveIntervals,
OptimizeLiveIntervals, StoreResults, RegStackify, and RegColoring), and
this also possibly create new optimization opportunities. I think we
should put all current and future optimization passes before RegStackify
(and related passes) unless there's a reason not to.


Repository:
  rL LLVM

https://reviews.llvm.org/D56356

Files:
  lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp


Index: lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -298,6 +298,12 @@
   // order of the arguments.
   addPass(createWebAssemblyCallIndirectFixup());
 
+  // Eliminate multiple-entry loops.
+  addPass(createWebAssemblyFixIrreducibleControlFlow());
+
+  // Do various transformations for exception handling.
+  addPass(createWebAssemblyLateEHPrepare());
+
   if (getOptLevel() != CodeGenOpt::None) {
     // LiveIntervals isn't commonly run this late. Re-establish preconditions.
     addPass(createWebAssemblyPrepareForLiveIntervals());
@@ -320,17 +326,9 @@
     addPass(createWebAssemblyRegColoring());
   }
 
-  // Eliminate multiple-entry loops. Do this before inserting explicit get_local
-  // and set_local operators because we create a new variable that we want
-  // converted into a local.
-  addPass(createWebAssemblyFixIrreducibleControlFlow());
-
   // Insert explicit get_local and set_local operators.
   addPass(createWebAssemblyExplicitLocals());
 
-  // Do various transformations for exception handling
-  addPass(createWebAssemblyLateEHPrepare());
-
   // Sort the blocks of the CFG into topological order, a prerequisite for
   // BLOCK and LOOP markers.
   addPass(createWebAssemblyCFGSort());


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