[PATCH] D118387: [U

[Kevin P. Neal via Phabricator via llvm-commits]

kpn created this revision.
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kpn requested review of this revision.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118387

Files:
  llvm/include/llvm/Transforms/Utils/SCCPSolver.h
  llvm/lib/Transforms/Scalar/SCCP.cpp
  llvm/lib/Transforms/Utils/SCCPSolver.cpp


Index: llvm/lib/Transforms/Utils/SCCPSolver.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SCCPSolver.cpp
+++ llvm/lib/Transforms/Utils/SCCPSolver.cpp
@@ -1616,7 +1616,8 @@
     const DataLayout &DL,
     std::function<const TargetLibraryInfo &(Function &)> GetTLI,
     LLVMContext &Ctx)
-    : Visitor(new SCCPInstVisitor(DL, std::move(GetTLI), Ctx)) {}
+    : Visitor(new SCCPInstVisitor(DL, std::move(GetTLI), Ctx)), getTLI(GetTLI) {
+}
 
 SCCPSolver::~SCCPSolver() {}
 
Index: llvm/lib/Transforms/Scalar/SCCP.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/SCCP.cpp
+++ llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -97,6 +97,18 @@
   return !LV.isUnknownOrUndef() && !isConstant(LV);
 }
 
+static bool canSCCPRemoveInstruction(Instruction *I,
+                                     const TargetLibraryInfo *TLI) {
+  if (wouldInstructionBeTriviallyDead(I, TLI))
+    return true;
+
+  // Defer to wouldInstructionBeTriviallyDead() for constrained fp.
+  if (isa<ConstrainedFPIntrinsic>(I))
+    return false;
+
+  return (!isa<CallInst>(I) || !I->mayHaveSideEffects()) && !I->isTerminator();
+}
+
 static bool tryToReplaceWithConstant(SCCPSolver &Solver, Value *V) {
   Constant *Const = nullptr;
   if (V->getType()->isStructTy()) {
@@ -127,7 +139,11 @@
   // Calls with "clang.arc.attachedcall" implicitly use the return value and
   // those uses cannot be updated with a constant.
   CallBase *CB = dyn_cast<CallBase>(V);
-  if (CB && ((CB->isMustTailCall() && !CB->isSafeToRemove()) ||
+  Function *CBF = nullptr;
+  if (CB)
+    CBF = CB->getFunction();
+  if (CB && ((CB->isMustTailCall() &&
+              !canSCCPRemoveInstruction(CB, &Solver.getTLI(*CBF))) ||
              CB->getOperandBundle(LLVMContext::OB_clang_arc_attachedcall))) {
     Function *F = CB->getCalledFunction();
 
@@ -156,7 +172,7 @@
     if (Inst.getType()->isVoidTy())
       continue;
     if (tryToReplaceWithConstant(Solver, &Inst)) {
-      if (Inst.isSafeToRemove())
+      if (canSCCPRemoveInstruction(&Inst, &Solver.getTLI(*BB.getParent())))
         Inst.eraseFromParent();
 
       MadeChanges = true;
Index: llvm/include/llvm/Transforms/Utils/SCCPSolver.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/SCCPSolver.h
+++ llvm/include/llvm/Transforms/Utils/SCCPSolver.h
@@ -51,6 +51,8 @@
 
   ~SCCPSolver();
 
+  std::function<const TargetLibraryInfo &(Function &)> getTLI;
+
   void addAnalysis(Function &F, AnalysisResultsForFn A);
 
   /// markBlockExecutable - This method can be used by clients to mark all of


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