Enable optimization suggested by Chris Lattner to not emit reloc stubs for

static global variables whose addresses are taken.  This allows us to
convert the following code for taking the address of a static function foo

        addis r2, r30, ha16(Ll1__2E_foo_2$non_lazy_ptr-"L00001$pb")
        lwz r3, lo16(Ll1__2E_foo_2$non_lazy_ptr-"L00001$pb")(r2)

which also includes linker stub code emitted at the end of the .s file not
shown here, and replace it with this:

        addis r2, r30, ha16(l1__2E_foo_2-"L00001$pb")
        la r3, lo16(l1__2E_foo_2-"L00001$pb")(r2)

which in addition to not needing linker help, also has no load instruction.
For those not up on PowerPC mnemonics, la is shorthand for add immediate.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18239 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 17 deletions

diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 4316abc613..f4e36bab2e 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringExtras.h"
 #include <set>
@@ -67,7 +68,7 @@ namespace {
     bool printInstruction(const MachineInstr *MI);
 
     void printMachineInstruction(const MachineInstr *MI);
-    void printOp(const MachineOperand &MO, bool LoadAddrOp = false);
+    void printOp(const MachineOperand &MO, bool IsCallOp = false);
 
     void printOperand(const MachineInstr *MI, unsigned OpNo, MVT::ValueType VT){
       const MachineOperand &MO = MI->getOperand(OpNo);
@@ -108,7 +109,8 @@ namespace {
       if (MI->getOperand(OpNo).isImmediate()) {
         O << "$+" << MI->getOperand(OpNo).getImmedValue() << '\n';
       } else {
-        printOp(MI->getOperand(OpNo));
+        printOp(MI->getOperand(OpNo), 
+                TM.getInstrInfo()->isCall(MI->getOpcode()));
       }
     }
     void printPICLabel(const MachineInstr *MI, unsigned OpNo,
@@ -120,7 +122,7 @@ namespace {
     void printSymbolHi(const MachineInstr *MI, unsigned OpNo,
                        MVT::ValueType VT) {
       O << "ha16(";
-      printOp(MI->getOperand(OpNo), true /* LoadAddrOp */);
+      printOp(MI->getOperand(OpNo));
       O << "-\"L0000" << LabelNumber << "$pb\")";
     }
     void printSymbolLo(const MachineInstr *MI, unsigned OpNo,
@@ -132,7 +134,7 @@ namespace {
         O << (short)MI->getOperand(OpNo).getImmedValue();
       } else {
         O << "lo16(";
-        printOp(MI->getOperand(OpNo), true /* LoadAddrOp */);
+        printOp(MI->getOperand(OpNo));
         O << "-\"L0000" << LabelNumber << "$pb\")";
       }
     }
@@ -307,8 +309,7 @@ FunctionPass *llvm::createAIXAsmPrinter(std::ostream &o, TargetMachine &tm) {
 // Include the auto-generated portion of the assembly writer
 #include "PowerPCGenAsmWriter.inc"
 
-void PowerPCAsmPrinter::printOp(const MachineOperand &MO,
-                              bool LoadAddrOp /* = false */) {
+void PowerPCAsmPrinter::printOp(const MachineOperand &MO, bool IsCallOp) {
   const MRegisterInfo &RI = *TM.getRegisterInfo();
   int new_symbol;
   
@@ -359,27 +360,23 @@ void PowerPCAsmPrinter::printOp(const MachineOperand &MO,
     // wary however not to output $stub for external functions whose addresses
     // are taken.  Those should be emitted as $non_lazy_ptr below.
     Function *F = dyn_cast<Function>(GV);
-    if (F && F->isExternal() && !LoadAddrOp &&
-        getTM().CalledFunctions.count(F)) {
+    if (F && F->isExternal() && IsCallOp && getTM().CalledFunctions.count(F)) {
       FnStubs.insert(Name);
       O << "L" << Name << "$stub";
       return;
     }
     
     // External or weakly linked global variables need non-lazily-resolved stubs
-    if ((GV->isExternal() || GV->hasWeakLinkage() || GV->hasLinkOnceLinkage()) 
+    if ((GV->isExternal() || GV->hasWeakLinkage() || GV->hasLinkOnceLinkage())
          && getTM().AddressTaken.count(GV)) {
-      GVStubs.insert(Name);
+      if (GV->hasLinkOnceLinkage())
+        LinkOnceStubs.insert(Name);
+      else
+        GVStubs.insert(Name);
       O << "L" << Name << "$non_lazy_ptr";
       return;
     }
-    
-    if (F && LoadAddrOp && getTM().AddressTaken.count(GV)) {
-      LinkOnceStubs.insert(Name);
-      O << "L" << Name << "$non_lazy_ptr";
-      return;
-    }
-            
+
     O << Mang->getValueName(GV);
     return;
   }