[ProfCheck][NFC] Make Function argument from branch weight setter optional (#166032)

This picks up from #166028, making the `Function` argument optional:
most cases don't need to provide it, but in e.g. InstCombine's case,
where the instruction (select, branch) is not attached to a function
yet, the function needs to be passed explicitly.

Co-authored-by: Florian Hahn <[email protected]>

Author: mtrofin

llvm/include/llvm/IR/ProfDataUtils.h

@@ -194,10 +194,11 @@ LLVM_ABI void setExplicitlyUnknownBranchWeights(Instruction &I,
 /// Like setExplicitlyUnknownBranchWeights(...), but only sets unknown branch
 /// weights in the new instruction if the parent function of the original
 /// instruction has an entry count. This is to not confuse users by injecting
-/// profile data into non-profiled functions.
-LLVM_ABI void setExplicitlyUnknownBranchWeightsIfProfiled(Instruction &I,
-                                                          Function &F,
-                                                          StringRef PassName);
+/// profile data into non-profiled functions. If \p F is nullptr, we will fetch
+/// the function from \p I.
+LLVM_ABI void
+setExplicitlyUnknownBranchWeightsIfProfiled(Instruction &I, StringRef PassName,
+                                            const Function *F = nullptr);
 
 /// Analogous to setExplicitlyUnknownBranchWeights, but for functions and their
 /// entry counts.

llvm/lib/IR/IRBuilder.cpp

@@ -1019,8 +1019,7 @@ Value *IRBuilderBase::CreateSelectWithUnknownProfile(Value *C, Value *True,
                                                      const Twine &Name) {
   Value *Ret = CreateSelectFMF(C, True, False, {}, Name);
   if (auto *SI = dyn_cast<SelectInst>(Ret)) {
-    setExplicitlyUnknownBranchWeightsIfProfiled(
-        *SI, *SI->getParent()->getParent(), PassName);
+    setExplicitlyUnknownBranchWeightsIfProfiled(*SI, PassName);
   }
   return Ret;
 }

llvm/lib/IR/ProfDataUtils.cpp

@@ -274,9 +274,12 @@ void llvm::setExplicitlyUnknownBranchWeights(Instruction &I,
 }
 
 void llvm::setExplicitlyUnknownBranchWeightsIfProfiled(Instruction &I,
-                                                       Function &F,
-                                                       StringRef PassName) {
-  if (std::optional<Function::ProfileCount> EC = F.getEntryCount();
+                                                       StringRef PassName,
+                                                       const Function *F) {
+  F = F ? F : I.getFunction();
+  assert(F && "Either pass a instruction attached to a Function, or explicitly "
+              "pass the Function that it will be attached to");
+  if (std::optional<Function::ProfileCount> EC = F->getEntryCount();
       EC && EC->getCount() > 0)
     setExplicitlyUnknownBranchWeights(I, PassName);
 }

llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp

@@ -1378,8 +1378,7 @@ static bool foldMemChr(CallInst *Call, DomTreeUpdater *DTU,
       IRB.CreateTrunc(Call->getArgOperand(1), ByteTy), BBNext, N);
   // We can't know the precise weights here, as they would depend on the value
   // distribution of Call->getArgOperand(1). So we just mark it as "unknown".
-  setExplicitlyUnknownBranchWeightsIfProfiled(*SI, *Call->getFunction(),
-                                              DEBUG_TYPE);
+  setExplicitlyUnknownBranchWeightsIfProfiled(*SI, DEBUG_TYPE);
   Type *IndexTy = DL.getIndexType(Call->getType());
   SmallVector<DominatorTree::UpdateType, 8> Updates;
 

llvm/lib/Transforms/InstCombine/InstCombineInternal.h

@@ -479,7 +479,7 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
                                      const Twine &NameStr = "",
                                      InsertPosition InsertBefore = nullptr) {
     auto *Sel = SelectInst::Create(C, S1, S2, NameStr, InsertBefore, nullptr);
-    setExplicitlyUnknownBranchWeightsIfProfiled(*Sel, F, DEBUG_TYPE);
+    setExplicitlyUnknownBranchWeightsIfProfiled(*Sel, DEBUG_TYPE, &F);
     return Sel;
   }
 

llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp

@@ -330,8 +330,7 @@ static void buildPartialUnswitchConditionalBranch(
       HasBranchWeights ? ComputeProfFrom.getMetadata(LLVMContext::MD_prof)
                        : nullptr);
   if (!HasBranchWeights)
-    setExplicitlyUnknownBranchWeightsIfProfiled(
-        *BR, *BR->getParent()->getParent(), DEBUG_TYPE);
+    setExplicitlyUnknownBranchWeightsIfProfiled(*BR, DEBUG_TYPE);
 }
 
 /// Copy a set of loop invariant values, and conditionally branch on them.

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -5214,8 +5214,7 @@ bool SimplifyCFGOpt::simplifyBranchOnICmpChain(BranchInst *BI,
     // We don't have any info about this condition.
     auto *Br = TrueWhenEqual ? Builder.CreateCondBr(ExtraCase, EdgeBB, NewBB)
                              : Builder.CreateCondBr(ExtraCase, NewBB, EdgeBB);
-    setExplicitlyUnknownBranchWeightsIfProfiled(*Br, *NewBB->getParent(),
-                                                DEBUG_TYPE);
+    setExplicitlyUnknownBranchWeightsIfProfiled(*Br, DEBUG_TYPE);
 
     OldTI->eraseFromParent();