[llvm] r175092 - Don't build tail calls to functions with three inreg arguments on x86-32 PIC.

[Nick Lewycky]

Author: nicholas
Date: Wed Feb 13 15:59:15 2013
New Revision: 175092

URL: http://llvm.org/viewvc/llvm-project?rev=175092&view=rev
Log:
Don't build tail calls to functions with three inreg arguments on x86-32 PIC.
Fixes PR15250!

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=175092&r1=175091&r2=175092&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Wed Feb 13 15:59:15 2013
@@ -2814,7 +2814,7 @@ X86TargetLowering::IsEligibleForTailCall
                                     const SmallVectorImpl<ISD::OutputArg> &Outs,
                                     const SmallVectorImpl<SDValue> &OutVals,
                                     const SmallVectorImpl<ISD::InputArg> &Ins,
-                                                     SelectionDAG& DAG) const {
+                                                     SelectionDAG &DAG) const {
   if (!IsTailCallConvention(CalleeCC) &&
       CalleeCC != CallingConv::C)
     return false;
@@ -2853,7 +2853,7 @@ X86TargetLowering::IsEligibleForTailCall
 
   // An stdcall caller is expected to clean up its arguments; the callee
   // isn't going to do that.
-  if (!CCMatch && CallerCC==CallingConv::X86_StdCall)
+  if (!CCMatch && CallerCC == CallingConv::X86_StdCall)
     return false;
 
   // Do not sibcall optimize vararg calls unless all arguments are passed via
@@ -2973,9 +2973,15 @@ X86TargetLowering::IsEligibleForTailCall
     // callee-saved registers are restored. These happen to be the same
     // registers used to pass 'inreg' arguments so watch out for those.
     if (!Subtarget->is64Bit() &&
-        !isa<GlobalAddressSDNode>(Callee) &&
-        !isa<ExternalSymbolSDNode>(Callee)) {
+        ((!isa<GlobalAddressSDNode>(Callee) &&
+          !isa<ExternalSymbolSDNode>(Callee)) ||
+         getTargetMachine().getRelocationModel() == Reloc::PIC_)) {
       unsigned NumInRegs = 0;
+      // In PIC we need an extra register to formulate the address computation
+      // for the callee.
+      unsigned MaxInRegs =
+          (getTargetMachine().getRelocationModel() == Reloc::PIC_) ? 2 : 3;
+
       for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
         CCValAssign &VA = ArgLocs[i];
         if (!VA.isRegLoc())
@@ -2984,7 +2990,7 @@ X86TargetLowering::IsEligibleForTailCall
         switch (Reg) {
         default: break;
         case X86::EAX: case X86::EDX: case X86::ECX:
-          if (++NumInRegs == 3)
+          if (++NumInRegs == MaxInRegs)
             return false;
           break;
         }