1 files changed, 28 insertions, 2 deletions
diff --git a/llvm/lib/Target/BPF/BPFAsmPrinter.cpp b/llvm/lib/Target/BPF/BPFAsmPrinter.cpp
index 77dc4a7..abe081c 100644
--- a/llvm/lib/Target/BPF/BPFAsmPrinter.cpp
+++ b/llvm/lib/Target/BPF/BPFAsmPrinter.cpp
@@ -88,6 +88,16 @@ bool BPFAsmPrinter::doFinalization(Module &M) {
     }
   }
 
+  for (GlobalObject &GO : M.global_objects()) {
+    if (!GO.hasExternalWeakLinkage())
+      continue;
+
+    if (!SawTrapCall && GO.getName() == BPF_TRAP) {
+      GO.eraseFromParent();
+      break;
+    }
+  }
+
   return AsmPrinter::doFinalization(M);
 }
 
@@ -160,6 +170,16 @@ bool BPFAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
 }
 
 void BPFAsmPrinter::emitInstruction(const MachineInstr *MI) {
+  if (MI->isCall()) {
+    for (const MachineOperand &Op : MI->operands()) {
+      if (Op.isGlobal()) {
+        if (const GlobalValue *GV = Op.getGlobal())
+          if (GV->getName() == BPF_TRAP)
+            SawTrapCall = true;
+      }
+    }
+  }
+
   BPF_MC::verifyInstructionPredicates(MI->getOpcode(),
                                       getSubtargetInfo().getFeatureBits());
 
@@ -195,6 +215,10 @@ void BPFAsmPrinter::emitJumpTableInfo() {
 
   const TargetLoweringObjectFile &TLOF = getObjFileLowering();
   const Function &F = MF->getFunction();
+
+  MCSection *Sec = OutStreamer->getCurrentSectionOnly();
+  MCSymbol *SecStart = Sec->getBeginSymbol();
+
   MCSection *JTS = TLOF.getSectionForJumpTable(F, TM);
   assert(MJTI->getEntryKind() == MachineJumpTableInfo::EK_BlockAddress);
   unsigned EntrySize = MJTI->getEntrySize(getDataLayout());
@@ -207,8 +231,10 @@ void BPFAsmPrinter::emitJumpTableInfo() {
     MCSymbol *JTStart = getJTPublicSymbol(JTI);
     OutStreamer->emitLabel(JTStart);
     for (const MachineBasicBlock *MBB : JTBBs) {
-      const MCExpr *LHS = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
-      OutStreamer->emitValue(LHS, EntrySize);
+      const MCExpr *Diff = MCBinaryExpr::createSub(
+          MCSymbolRefExpr::create(MBB->getSymbol(), OutContext),
+          MCSymbolRefExpr::create(SecStart, OutContext), OutContext);
+      OutStreamer->emitValue(Diff, EntrySize);
     }
     const MCExpr *JTSize =
         MCConstantExpr::create(JTBBs.size() * EntrySize, OutContext);