If there are no machine instructions emitted for a function, then insert

a "nop" instruction so that we don't have the function's label associated
with something that it's not supposed to be associated with.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46394 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 16 insertions, 16 deletions

diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index bab1af3..6a1451d 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -30,6 +30,7 @@
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/Support/Mangler.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/CommandLine.h"
@@ -813,6 +814,18 @@ bool DarwinAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
   // Emit pre-function debug information.
   DW.BeginFunction(&MF);
 
+  // If the function is empty, then we need to emit *something*. Otherwise, the
+  // function's label might be associated with something that it wasn't meant to
+  // be associated with. We emit a noop in this situation.
+  MachineFunction::iterator I = MF.begin();
+
+  if (++I == MF.end()) {
+    MachineBasicBlock &MBB = MF.front();
+
+    if (MBB.begin() == MBB.end())
+      BuildMI(MBB, MBB.end(), TM.getInstrInfo()->get(PPC::NOP));
+  }
+
   // Print out code for the function.
   for (MachineFunction::const_iterator I = MF.begin(), E = MF.end();
        I != E; ++I) {
@@ -821,8 +834,8 @@ bool DarwinAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
       printBasicBlockLabel(I, true);
       O << '\n';
     }
-    for (MachineBasicBlock::const_iterator II = I->begin(), E = I->end();
-         II != E; ++II) {
+    for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
+         II != IE; ++II) {
       // Print the assembly for the instruction.
       O << "\t";
       printMachineInstruction(II);
diff --git a/lib/Transforms/Scalar/SimplifyCFG.cpp b/lib/Transforms/Scalar/SimplifyCFG.cpp
index 9d0757a..3d1a5be 100644
--- a/lib/Transforms/Scalar/SimplifyCFG.cpp
+++ b/lib/Transforms/Scalar/SimplifyCFG.cpp
@@ -26,7 +26,6 @@
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Constants.h"
 #include "llvm/Instructions.h"
-#include "llvm/Intrinsics.h"
 #include "llvm/Module.h"
 #include "llvm/ParameterAttributes.h"
 #include "llvm/Support/CFG.h"
@@ -155,20 +154,8 @@ static bool RemoveUnreachableBlocks(Function &F) {
   bool Changed = MarkAliveBlocks(F.begin(), Reachable);
   
   // If there are unreachable blocks in the CFG...
-  if (Reachable.size() == F.size()) {
-    if (F.size() == 1) {
-      // If the function has only one block with an "unreachable" instruction,
-      // then we should create *some* code for it. Issue a "trap" instead.
-      BasicBlock &BB = F.front();
-
-      if (BB.size() == 1 && dyn_cast<UnreachableInst>(&BB.front()))
-        new CallInst(Intrinsic::getDeclaration(F.getParent(),
-                                               Intrinsic::trap),
-                     "", &BB.front());
-    }
-
+  if (Reachable.size() == F.size())
     return Changed;
-  }
   
   assert(Reachable.size() < F.size());
   NumSimpl += F.size()-Reachable.size();