From: Eric Christopher <echristo@apple.com>
Date: Tue, 22 Feb 2011 01:37:10 +0000 (+0000)
Subject: Only use blx for external function calls on thumb, these could be fixed
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=872f4a224711ef55b821746fc7a24b9260fee370;p=oota-llvm.git

Only use blx for external function calls on thumb, these could be fixed
up by the dynamic linker, but it's better to use the correct instruction
to begin with.

Fixes rdar://9011034


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126176 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/ARM/ARMFastISel.cpp b/lib/Target/ARM/ARMFastISel.cpp
index 9f295302db0..26f48b30831 100644
--- a/lib/Target/ARM/ARMFastISel.cpp
+++ b/lib/Target/ARM/ARMFastISel.cpp
@@ -172,6 +172,7 @@ class ARMFastISel : public FastISel {
     unsigned ARMMaterializeGV(const GlobalValue *GV, EVT VT);
     unsigned ARMMoveToFPReg(EVT VT, unsigned SrcReg);
     unsigned ARMMoveToIntReg(EVT VT, unsigned SrcReg);
+    unsigned ARMSelectCallOp(const GlobalValue *GV);
 
     // Call handling routines.
   private:
@@ -1633,6 +1634,25 @@ bool ARMFastISel::SelectRet(const Instruction *I) {
   return true;
 }
 
+unsigned ARMFastISel::ARMSelectCallOp(const GlobalValue *GV) {
+
+  // Depend our opcode for thumb on whether or not we're targeting an
+  // externally callable function. For libcalls we'll just pass a NULL GV
+  // in here.
+  bool isExternal = false;
+  if (!GV || GV->hasExternalLinkage()) isExternal = true;
+  
+  // Darwin needs the r9 versions of the opcodes.
+  bool isDarwin = Subtarget->isTargetDarwin();
+  if (isThumb && isExternal) {
+    return isDarwin ? ARM::tBLXi_r9 : ARM::tBLXi;
+  } else if (isThumb) {
+    return isDarwin ? ARM::tBLr9 : ARM::tBL;
+  } else  {
+    return isDarwin ? ARM::BLr9 : ARM::BL;
+  }
+}
+
 // A quick function that will emit a call for a named libcall in F with the
 // vector of passed arguments for the Instruction in I. We can assume that we
 // can emit a call for any libcall we can produce. This is an abridged version
@@ -1694,20 +1714,17 @@ bool ARMFastISel::ARMEmitLibcall(const Instruction *I, RTLIB::Libcall Call) {
   // Issue the call, BLXr9 for darwin, BLX otherwise. This uses V5 ops.
   // TODO: Turn this into the table of arm call ops.
   MachineInstrBuilder MIB;
-  unsigned CallOpc;
-  if(isThumb) {
-    CallOpc = Subtarget->isTargetDarwin() ? ARM::tBLXi_r9 : ARM::tBLXi;
+  unsigned CallOpc = ARMSelectCallOp(NULL);
+  if(isThumb)
     // Explicitly adding the predicate here.
     MIB = AddDefaultPred(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
                          TII.get(CallOpc)))
                          .addExternalSymbol(TLI.getLibcallName(Call));
-  } else {
-    CallOpc = Subtarget->isTargetDarwin() ? ARM::BLr9 : ARM::BL;
+  else
     // Explicitly adding the predicate here.
     MIB = AddDefaultPred(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
                          TII.get(CallOpc))
           .addExternalSymbol(TLI.getLibcallName(Call)));
-  }
 
   // Add implicit physical register uses to the call.
   for (unsigned i = 0, e = RegArgs.size(); i != e; ++i)
@@ -1813,21 +1830,18 @@ bool ARMFastISel::SelectCall(const Instruction *I) {
   // Issue the call, BLXr9 for darwin, BLX otherwise. This uses V5 ops.
   // TODO: Turn this into the table of arm call ops.
   MachineInstrBuilder MIB;
-  unsigned CallOpc;
+  unsigned CallOpc = ARMSelectCallOp(GV);
   // Explicitly adding the predicate here.
-  if(isThumb) {
-    CallOpc = Subtarget->isTargetDarwin() ? ARM::tBLXi_r9 : ARM::tBLXi;
+  if(isThumb)
     // Explicitly adding the predicate here.
     MIB = AddDefaultPred(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
                          TII.get(CallOpc)))
           .addGlobalAddress(GV, 0, 0);
-  } else {
-    CallOpc = Subtarget->isTargetDarwin() ? ARM::BLr9 : ARM::BL;
+  else
     // Explicitly adding the predicate here.
     MIB = AddDefaultPred(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
                          TII.get(CallOpc))
           .addGlobalAddress(GV, 0, 0));
-  }
   
   // Add implicit physical register uses to the call.
   for (unsigned i = 0, e = RegArgs.size(); i != e; ++i)