In Thumb1 mode the constant might be materialized via the load from constpool. Emit unwinding information in case when this load from constpool is used to change the stack pointer in the prologue.

llvm-svn: 127105

1 files changed, 16 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index fa06bf7eeb5..135148d1645 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -817,6 +817,7 @@ void ARMAsmPrinter::EmitUnwindingInstruction(const MachineInstr *MI) {
 
   const MachineFunction &MF = *MI->getParent()->getParent();
   const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
+  const ARMFunctionInfo &AFI = *MF.getInfo<ARMFunctionInfo>();
 
   unsigned FramePtr = RegInfo->getFrameRegister(MF);
   unsigned Opc = MI->getOpcode();
@@ -896,10 +897,23 @@ void ARMAsmPrinter::EmitUnwindingInstruction(const MachineInstr *MI) {
       case ARM::tADDrSPi:
         Offset = -MI->getOperand(2).getImm()*4;
         break;
-      case ARM::tLDRpci:
-        assert(0 && "Not implemented yet!");
+      case ARM::tLDRpci: {
+        // Grab the constpool index and check, whether it corresponds to
+        // original or cloned constpool entry.
+        unsigned CPI = MI->getOperand(1).getIndex();
+        const MachineConstantPool *MCP = MF.getConstantPool();
+        if (CPI >= MCP->getConstants().size())
+          CPI = AFI.getOriginalCPIdx(CPI);
+        assert(CPI != -1U && "Invalid constpool index");
+
+        // Derive the actual offset.
+        const MachineConstantPoolEntry &CPE = MCP->getConstants()[CPI];
+        assert(!CPE.isMachineConstantPoolEntry() && "Invalid constpool entry");
+        // FIXME: Check for user, it should be "add" instruction!
+        Offset = -cast<ConstantInt>(CPE.Val.ConstVal)->getSExtValue();
         break;
       }
+      }
 
       if (DstReg == FramePtr && FramePtr != ARM::SP)
         // Set-up of the frame pointer.