Revert "[LoopInfo] Pointer to stack object may not be loop invariant in a coroutine function (#149936)" (#157986)

Since #156788 has resolved #149604, we can revert this workaround now.

Author: NewSigma

llvm/include/llvm/Analysis/LoopInfo.h

@@ -59,12 +59,11 @@ class LLVM_ABI Loop : public LoopBase<BasicBlock, Loop> {
   };
 
   /// Return true if the specified value is loop invariant.
-  bool isLoopInvariant(const Value *V, bool HasCoroSuspendInst = false) const;
+  bool isLoopInvariant(const Value *V) const;
 
   /// Return true if all the operands of the specified instruction are loop
   /// invariant.
-  bool hasLoopInvariantOperands(const Instruction *I,
-                                bool HasCoroSuspendInst = false) const;
+  bool hasLoopInvariantOperands(const Instruction *I) const;
 
   /// If the given value is an instruction inside of the loop and it can be
   /// hoisted, do so to make it trivially loop-invariant.

llvm/include/llvm/Transforms/Utils/LoopUtils.h

@@ -185,8 +185,7 @@ LLVM_ABI bool hoistRegion(DomTreeNode *, AAResults *, LoopInfo *,
                           TargetLibraryInfo *, Loop *, MemorySSAUpdater &,
                           ScalarEvolution *, ICFLoopSafetyInfo *,
                           SinkAndHoistLICMFlags &, OptimizationRemarkEmitter *,
-                          bool, bool AllowSpeculation,
-                          bool HasCoroSuspendInst = false);
+                          bool, bool AllowSpeculation);
 
 /// Return true if the induction variable \p IV in a Loop whose latch is
 /// \p LatchBlock would become dead if the exit test \p Cond were removed.

llvm/lib/Analysis/LoopInfo.cpp

@@ -58,26 +58,14 @@ static cl::opt<bool, true>
 // Loop implementation
 //
 
-bool Loop::isLoopInvariant(const Value *V, bool HasCoroSuspendInst) const {
-  if (const Instruction *I = dyn_cast<Instruction>(V)) {
-    // FIXME: this is semantically inconsistent. We're tracking a proper fix in
-    // issue #149604.
-    // If V is a pointer to stack object and L contains a coro.suspend function
-    // call, then V may not be loop invariant because the ramp function and
-    // resume function have different stack frames.
-    if (HasCoroSuspendInst && isa<AllocaInst>(I))
-      return false;
-    else
-      return !contains(I);
-  }
+bool Loop::isLoopInvariant(const Value *V) const {
+  if (const Instruction *I = dyn_cast<Instruction>(V))
+    return !contains(I);
   return true; // All non-instructions are loop invariant
 }
 
-bool Loop::hasLoopInvariantOperands(const Instruction *I,
-                                    bool HasCoroSuspendInst) const {
-  return all_of(I->operands(), [&](Value *V) {
-    return isLoopInvariant(V, HasCoroSuspendInst);
-  });
+bool Loop::hasLoopInvariantOperands(const Instruction *I) const {
+  return all_of(I->operands(), [&](Value *V) { return isLoopInvariant(V); });
 }
 
 bool Loop::makeLoopInvariant(Value *V, bool &Changed, Instruction *InsertPt,

llvm/lib/Transforms/Scalar/LICM.cpp

@@ -474,7 +474,7 @@ bool LoopInvariantCodeMotion::runOnLoop(Loop *L, AAResults *AA, LoopInfo *LI,
   if (Preheader)
     Changed |= hoistRegion(DT->getNode(L->getHeader()), AA, LI, DT, AC, TLI, L,
                            MSSAU, SE, &SafetyInfo, Flags, ORE, LoopNestMode,
-                           LicmAllowSpeculation, HasCoroSuspendInst);
+                           LicmAllowSpeculation);
 
   // Now that all loop invariants have been removed from the loop, promote any
   // memory references to scalars that we can.
@@ -892,7 +892,7 @@ bool llvm::hoistRegion(DomTreeNode *N, AAResults *AA, LoopInfo *LI,
                        ICFLoopSafetyInfo *SafetyInfo,
                        SinkAndHoistLICMFlags &Flags,
                        OptimizationRemarkEmitter *ORE, bool LoopNestMode,
-                       bool AllowSpeculation, bool HasCoroSuspendInst) {
+                       bool AllowSpeculation) {
   // Verify inputs.
   assert(N != nullptr && AA != nullptr && LI != nullptr && DT != nullptr &&
          CurLoop != nullptr && SafetyInfo != nullptr &&
@@ -925,7 +925,7 @@ bool llvm::hoistRegion(DomTreeNode *N, AAResults *AA, LoopInfo *LI,
       // TODO: It may be safe to hoist if we are hoisting to a conditional block
       // and we have accurately duplicated the control flow from the loop header
       // to that block.
-      if (CurLoop->hasLoopInvariantOperands(&I, HasCoroSuspendInst) &&
+      if (CurLoop->hasLoopInvariantOperands(&I) &&
           canSinkOrHoistInst(I, AA, DT, CurLoop, MSSAU, true, Flags, ORE) &&
           isSafeToExecuteUnconditionally(I, DT, TLI, CurLoop, SafetyInfo, ORE,
                                          Preheader->getTerminator(), AC,
@@ -975,7 +975,7 @@ bool llvm::hoistRegion(DomTreeNode *N, AAResults *AA, LoopInfo *LI,
                SafetyInfo->doesNotWriteMemoryBefore(I, CurLoop);
       };
       if ((IsInvariantStart(I) || isGuard(&I)) &&
-          CurLoop->hasLoopInvariantOperands(&I, HasCoroSuspendInst) &&
+          CurLoop->hasLoopInvariantOperands(&I) &&
           MustExecuteWithoutWritesBefore(I)) {
         hoist(I, DT, CurLoop, CFH.getOrCreateHoistedBlock(BB), SafetyInfo,
               MSSAU, SE, ORE);