[WebAssembly] Run ExplicitLocals pass after CFGStackify

[aheejin]

Summary

While this does not change any final output, this will greatly simplify
fixing unwind destination mismatches in CFGStackify (D48345), because we
have to create some new registers there.

[aheejin]

test/CodeGen/WebAssembly/cfg-stackify-dbg-skip.ll

10

This does not mean this patch changes the final output. The reason for the change is this test stops after CFGStackify and now we run ExplicitLocals after CFGStackify.

lib/Target/WebAssembly/WebAssembly.h

 
 // Late passes.
 FunctionPass *createWebAssemblyReplacePhysRegs();
 FunctionPass *createWebAssemblyPrepareForLiveIntervals();
 FunctionPass *createWebAssemblyOptimizeLiveIntervals();
 FunctionPass *createWebAssemblyMemIntrinsicResults();
 FunctionPass *createWebAssemblyRegStackify();
 FunctionPass *createWebAssemblyRegColoring();
-FunctionPass *createWebAssemblyExplicitLocals();
 FunctionPass *createWebAssemblyFixIrreducibleControlFlow();
 FunctionPass *createWebAssemblyLateEHPrepare();
 FunctionPass *createWebAssemblyCFGSort();
 FunctionPass *createWebAssemblyCFGStackify();
+FunctionPass *createWebAssemblyExplicitLocals();
 FunctionPass *createWebAssemblyLowerBrUnless();
 FunctionPass *createWebAssemblyRegNumbering();
 FunctionPass *createWebAssemblyPeephole();
 FunctionPass *createWebAssemblyCallIndirectFixup();
 
 // PassRegistry initialization declarations.
 void initializeWebAssemblyAddMissingPrototypesPass(PassRegistry &);
 void initializeWebAssemblyLowerEmscriptenEHSjLjPass(PassRegistry &);
 void initializeLowerGlobalDtorsPass(PassRegistry &);
 void initializeFixFunctionBitcastsPass(PassRegistry &);
 void initializeOptimizeReturnedPass(PassRegistry &);
 void initializeWebAssemblyArgumentMovePass(PassRegistry &);
 void initializeWebAssemblySetP2AlignOperandsPass(PassRegistry &);
 void initializeWebAssemblyReplacePhysRegsPass(PassRegistry &);
 void initializeWebAssemblyPrepareForLiveIntervalsPass(PassRegistry &);
 void initializeWebAssemblyOptimizeLiveIntervalsPass(PassRegistry &);
 void initializeWebAssemblyMemIntrinsicResultsPass(PassRegistry &);
 void initializeWebAssemblyRegStackifyPass(PassRegistry &);
 void initializeWebAssemblyRegColoringPass(PassRegistry &);
-void initializeWebAssemblyExplicitLocalsPass(PassRegistry &);
 void initializeWebAssemblyFixIrreducibleControlFlowPass(PassRegistry &);
 void initializeWebAssemblyLateEHPreparePass(PassRegistry &);
 void initializeWebAssemblyExceptionInfoPass(PassRegistry &);
 void initializeWebAssemblyCFGSortPass(PassRegistry &);
 void initializeWebAssemblyCFGStackifyPass(PassRegistry &);
+void initializeWebAssemblyExplicitLocalsPass(PassRegistry &);
 void initializeWebAssemblyLowerBrUnlessPass(PassRegistry &);
 void initializeWebAssemblyRegNumberingPass(PassRegistry &);
 void initializeWebAssemblyPeepholePass(PassRegistry &);
 void initializeWebAssemblyCallIndirectFixupPass(PassRegistry &);
 
 } // end namespace llvm
 
 #endif

lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

extern "C" void LLVMInitializeWebAssemblyTarget() {
   initializeWebAssemblyArgumentMovePass(PR);
   initializeWebAssemblySetP2AlignOperandsPass(PR);
   initializeWebAssemblyReplacePhysRegsPass(PR);
   initializeWebAssemblyPrepareForLiveIntervalsPass(PR);
   initializeWebAssemblyOptimizeLiveIntervalsPass(PR);
   initializeWebAssemblyMemIntrinsicResultsPass(PR);
   initializeWebAssemblyRegStackifyPass(PR);
   initializeWebAssemblyRegColoringPass(PR);
-  initializeWebAssemblyExplicitLocalsPass(PR);
   initializeWebAssemblyFixIrreducibleControlFlowPass(PR);
   initializeWebAssemblyLateEHPreparePass(PR);
   initializeWebAssemblyExceptionInfoPass(PR);
   initializeWebAssemblyCFGSortPass(PR);
   initializeWebAssemblyCFGStackifyPass(PR);
+  initializeWebAssemblyExplicitLocalsPass(PR);
   initializeWebAssemblyLowerBrUnlessPass(PR);
   initializeWebAssemblyRegNumberingPass(PR);
   initializeWebAssemblyPeepholePass(PR);
   initializeWebAssemblyCallIndirectFixupPass(PR);
 }
 
 //===----------------------------------------------------------------------===//
 // WebAssembly Lowering public interface.
if (getOptLevel() != CodeGenOpt::None) {
     addPass(createWebAssemblyRegStackify());
 
     // Run the register coloring pass to reduce the total number of registers.
     // This runs after stackification so that it doesn't consider registers
     // that become stackified.
     addPass(createWebAssemblyRegColoring());
   }
 
-  // Insert explicit local.get and local.set operators.
-  addPass(createWebAssemblyExplicitLocals());
-
   // Sort the blocks of the CFG into topological order, a prerequisite for
   // BLOCK and LOOP markers.
   addPass(createWebAssemblyCFGSort());
 
   // Insert BLOCK and LOOP markers.
   addPass(createWebAssemblyCFGStackify());
 
+  // Insert explicit local.get and local.set operators.
+  addPass(createWebAssemblyExplicitLocals());
+
   // Lower br_unless into br_if.
   addPass(createWebAssemblyLowerBrUnless());
 
   // Perform the very last peephole optimizations on the code.
   if (getOptLevel() != CodeGenOpt::None)
     addPass(createWebAssemblyPeephole());
 
   // Create a mapping from LLVM CodeGen virtual registers to wasm registers.
   addPass(createWebAssemblyRegNumbering());
 }

test/CodeGen/WebAssembly/cfg-stackify-dbg-skip.ll

 ; RUN: llc %s -stop-after wasm-cfg-stackify -o - | FileCheck %s
 
 ; The test ensures "block" instruction is not inserted in the middle of a group
 ; of instructions that form a stackified expression when DBG_VALUE is present
 ; among them.
 
 ; CHECK: body:
 ; CHECK: BLOCK
 ;                       <-- Stackified expression starts
-; CHECK-NEXT: LOCAL_GET_I64
 ; CHECK-NEXT: I32_WRAP_I64
 ; CHECK-NEXT: DBG_VALUE
 ;                       <-- BLOCK should NOT be placed here!
 ; CHECK-NEXT: BR_UNLESS
 ;                       <-- Stackified expression ends
 
 target triple = "wasm32-unknown-unknown"