XCore target: remove incorrect DebugLoc entries from prologue

[robertlytton]

Summary

This was causing the prologue_end to be incorrectly positioned.

[• friedgold]

LGTM

[robertlytton]

Closed by commit rL212318 (authored by rlytton).

lib/Target/XCore/XCoreFrameLowering.cpp

void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
   MachineBasicBlock::iterator MBBI = MBB.begin();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   MachineModuleInfo *MMI = &MF.getMMI();
   const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
   const XCoreInstrInfo &TII =
     *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
   XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
-  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+  // Debug location must be unknown since the first debug location is used
+  // to determine the end of the prologue.
+  DebugLoc dl;
 
   if (MFI->getMaxAlignment() > getStackAlignment())
     report_fatal_error("emitPrologue unsupported alignment: "
                        + Twine(MFI->getMaxAlignment()));
 
   const AttributeSet &PAL = MF.getFunction()->getAttributes();
   if (PAL.hasAttrSomewhere(Attribute::Nest))
     BuildMI(MBB, MBBI, dl, TII.get(XCore::LDWSP_ru6), XCore::R11).addImm(0);
if (CSI.empty())
     return true;
 
   MachineFunction *MF = MBB.getParent();
   const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
   XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
   bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
 
   DebugLoc DL;
-  if (MI != MBB.end())
+  if (MI != MBB.end() && !MI->isDebugValue())
     DL = MI->getDebugLoc();
 
   for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
                                                     it != CSI.end(); ++it) {
     unsigned Reg = it->getReg();
     assert(Reg != XCore::LR && !(Reg == XCore::R10 && hasFP(*MF)) &&
            "LR & FP are always handled in emitPrologue");
 

lib/Target/XCore/XCoreInstrInfo.cpp

 void XCoreInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
                                          MachineBasicBlock::iterator I,
                                          unsigned SrcReg, bool isKill,
                                          int FrameIndex,
                                          const TargetRegisterClass *RC,
                                          const TargetRegisterInfo *TRI) const
 {
   DebugLoc DL;
-  if (I != MBB.end()) DL = I->getDebugLoc();
+  if (I != MBB.end() && !I->isDebugValue())
+    DL = I->getDebugLoc();
   MachineFunction *MF = MBB.getParent();
   const MachineFrameInfo &MFI = *MF->getFrameInfo();
   MachineMemOperand *MMO =
     MF->getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIndex),
                              MachineMemOperand::MOStore,
                              MFI.getObjectSize(FrameIndex),
                              MFI.getObjectAlignment(FrameIndex));
   BuildMI(MBB, I, DL, get(XCore::STWFI))
     .addReg(SrcReg, getKillRegState(isKill))
     .addFrameIndex(FrameIndex)
     .addImm(0)
     .addMemOperand(MMO);
 }
 
 void XCoreInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
                                           MachineBasicBlock::iterator I,
                                           unsigned DestReg, int FrameIndex,
                                           const TargetRegisterClass *RC,
                                           const TargetRegisterInfo *TRI) const
 {
   DebugLoc DL;
-  if (I != MBB.end()) DL = I->getDebugLoc();
+  if (I != MBB.end() && !I->isDebugValue())
+    DL = I->getDebugLoc();
   MachineFunction *MF = MBB.getParent();
   const MachineFrameInfo &MFI = *MF->getFrameInfo();
   MachineMemOperand *MMO =
     MF->getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIndex),
                              MachineMemOperand::MOLoad,
                              MFI.getObjectSize(FrameIndex),
                              MFI.getObjectAlignment(FrameIndex));
   BuildMI(MBB, I, DL, get(XCore::LDWFI), DestReg)
static bool isImmMskBitp(unsigned val) {
   return (N >= 1 && N <= 8) || N == 16 || N == 24 || N == 32;
 }
 
 MachineBasicBlock::iterator XCoreInstrInfo::loadImmediate(
                                               MachineBasicBlock &MBB,
                                               MachineBasicBlock::iterator MI,
                                               unsigned Reg, uint64_t Value) const {
   DebugLoc dl;
-  if (MI != MBB.end()) dl = MI->getDebugLoc();
+  if (MI != MBB.end() && !MI->isDebugValue())
+    dl = MI->getDebugLoc();
   if (isImmMskBitp(Value)) {
     int N = Log2_32(Value) + 1;
     return BuildMI(MBB, MI, dl, get(XCore::MKMSK_rus), Reg).addImm(N);
   }
   if (isImmU16(Value)) {
     int Opcode = isImmU6(Value) ? XCore::LDC_ru6 : XCore::LDC_lru6;
     return BuildMI(MBB, MI, dl, get(Opcode), Reg).addImm(Value);
   }
   MachineConstantPool *ConstantPool = MBB.getParent()->getConstantPool();
   const Constant *C = ConstantInt::get(
         Type::getInt32Ty(MBB.getParent()->getFunction()->getContext()), Value);
   unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
   return BuildMI(MBB, MI, dl, get(XCore::LDWCP_lru6), Reg)
             .addConstantPoolIndex(Idx);
 }

test/CodeGen/XCore/dwarf_debug.ll

+; RUN: llc < %s -march=xcore -O0 | FileCheck %s
+
+; target datalayout = "e-m:e-p:32:32-i1:8:32-i8:8:32-i16:16:32-i64:32-f64:32-a:0:32-n32"
+; target triple = "xcore"
+
+; CHECK-LABEL: f
+; CHECK: entsp 2
+; ...the prologue...
+; CHECK: .loc 1 2 0 prologue_end      # :2:0
+; CHECK: add r0, r0, 1
+; CHECK: retsp 2
+define i32 @f(i32 %a) {
+entry:
+  %a.addr = alloca i32, align 4
+  store i32 %a, i32* %a.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %a.addr}, metadata !11), !dbg !12
+  %0 = load i32* %a.addr, align 4, !dbg !12
+  %add = add nsw i32 %0, 1, !dbg !12
+  ret i32 %add, !dbg !12
+}
+
+declare void @llvm.dbg.declare(metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!9, !10}
+!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 1}
+!1 = metadata !{metadata !"", metadata !""}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"f", metadata !"f", metadata !"", i32 2, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @f, null, null, metadata !2, i32 2}
+!5 = metadata !{i32 786473, metadata !1}
+!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, null, null, null}
+!7 = metadata !{metadata !8, metadata !8}
+!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5}
+!9 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!10 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
+!11 = metadata !{i32 786689, metadata !4, metadata !"a", metadata !5, i32 16777218, metadata !8, i32 0, i32 0}
+!12 = metadata !{i32 2, i32 0, metadata !4, null}
+