[BOLT] LongJmp speedup refactoring

[yota9]

Summary

Run tentativeLayoutRelocMode twice only if UseOldText option was passed.
Refactor BF loop to break on condtition met.

[yota9]

Clang-format

[rafauler]

Awesome! Thanks!

bolt/lib/Passes/LongJmp.cpp

uint64_t LongJmpPass::tentativeLayoutRelocMode(
     const BinaryContext &BC, std::vector<BinaryFunction *> &SortedFunctions,
     uint64_t DotAddress) {
 
   // Compute hot cold frontier
   uint32_t LastHotIndex = -1u;
   uint32_t CurrentIndex = 0;
   if (opts::HotFunctionsAtEnd) {
     for (BinaryFunction *BF : SortedFunctions) {
-      if (BF->hasValidIndex() && LastHotIndex == -1u)
+      if (BF->hasValidIndex()) {
         LastHotIndex = CurrentIndex;
+        break;
+      }
+
       ++CurrentIndex;
     }
   } else {
     for (BinaryFunction *BF : SortedFunctions) {
-      if (!BF->hasValidIndex() && LastHotIndex == -1u)
+      if (!BF->hasValidIndex()) {
         LastHotIndex = CurrentIndex;
+        break;
+      }
+
       ++CurrentIndex;
     }
   }
 
   // Hot
   CurrentIndex = 0;
   bool ColdLayoutDone = false;
   for (BinaryFunction *Func : SortedFunctions) {
for (BinaryFunction *Func : SortedFunctions) {
         DotAddress += Func->estimateColdSize();
       tentativeBBLayout(*Func);
     }
 
     return;
   }
 
   // Relocation mode
-  uint64_t EstimatedTextSize = tentativeLayoutRelocMode(BC, SortedFunctions, 0);
+  uint64_t EstimatedTextSize = 0;
+  if (opts::UseOldText) {
+    EstimatedTextSize = tentativeLayoutRelocMode(BC, SortedFunctions, 0);
 
     // Initial padding
-  if (opts::UseOldText && EstimatedTextSize <= BC.OldTextSectionSize) {
+    if (EstimatedTextSize <= BC.OldTextSectionSize) {
       DotAddress = BC.OldTextSectionAddress;
       uint64_t Pad = offsetToAlignment(DotAddress, llvm::Align(opts::AlignText));
-    if (Pad + EstimatedTextSize <= BC.OldTextSectionSize)
+      if (Pad + EstimatedTextSize <= BC.OldTextSectionSize) {
         DotAddress += Pad;
-  } else {
-    DotAddress = alignTo(BC.LayoutStartAddress, opts::AlignText);
       }
+    }
+  }
+
+  if (!EstimatedTextSize || EstimatedTextSize > BC.OldTextSectionSize)
+    DotAddress = alignTo(BC.LayoutStartAddress, opts::AlignText);
 
   tentativeLayoutRelocMode(BC, SortedFunctions, DotAddress);
 }
 
 bool LongJmpPass::usesStub(const BinaryFunction &Func,
                            const MCInst &Inst) const {
   const MCSymbol *TgtSym = Func.getBinaryContext().MIB->getTargetSymbol(Inst);
   const BinaryBasicBlock *TgtBB = Func.getBasicBlockForLabel(TgtSym);