[DwarfDebug] Dump call site debug info

Dump the DWARF information about call sites and call site parameters into
debug info sections.

The patch also provides an interface for the interpretation of instructions
that could load values of a call site parameters in order to generate DWARF
about the call site parameters.

([13/13] Introduce the debug entry values.)

Co-authored-by: Ananth Sowda <asowda@cisco.com>
Co-authored-by: Nikola Prica <nikola.prica@rt-rk.com>
Co-authored-by: Ivan Baev <ibaev@cisco.com>

Differential Revision: https://reviews.llvm.org/D60716

llvm-svn: 365467

1 files changed, 40 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 868617ffe14..f7f3e11f18a 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -23,6 +23,7 @@
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/CodeGen/TargetSchedule.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCInstrItineraries.h"
 #include "llvm/Support/CommandLine.h"
@@ -1120,6 +1121,45 @@ bool TargetInstrInfo::hasLowDefLatency(const TargetSchedModel &SchedModel,
   return (DefCycle != -1 && DefCycle <= 1);
 }
 
+Optional<ParamLoadedValue>
+TargetInstrInfo::describeLoadedValue(const MachineInstr &MI) const {
+  const MachineOperand *Op = nullptr;
+  DIExpression *Expr = nullptr;
+
+  const MachineOperand *SrcRegOp, *DestRegOp;
+  const MachineFunction *MF = MI.getMF();
+  if (isCopyInstr(MI, SrcRegOp, DestRegOp)) {
+    Expr = DIExpression::get(MF->getFunction().getContext(), {});
+    Op = SrcRegOp;
+    return ParamLoadedValue(Op, Expr);
+  } else if (MI.isMoveImmediate()) {
+    Expr = DIExpression::get(MF->getFunction().getContext(), {});
+    Op = &MI.getOperand(1);
+    return ParamLoadedValue(Op, Expr);
+  } else if (MI.hasOneMemOperand()) {
+    int64_t Offset;
+    const auto &TRI = MF->getSubtarget().getRegisterInfo();
+    const auto &TII = MF->getSubtarget().getInstrInfo();
+    const MachineOperand *BaseOp;
+    if (!TII->getMemOperandWithOffset(MI, BaseOp, Offset, TRI))
+      return None;
+    unsigned CastedOffset = static_cast<unsigned>(Offset);
+    if (Offset > 0)
+      Expr = DIExpression::get(
+          MF->getFunction().getContext(),
+          {dwarf::DW_OP_plus_uconst, CastedOffset, dwarf::DW_OP_deref});
+    else
+      Expr = DIExpression::get(MF->getFunction().getContext(),
+                               {dwarf::DW_OP_constu, -CastedOffset,
+                                dwarf::DW_OP_minus, dwarf::DW_OP_deref});
+
+    Op = BaseOp;
+    return ParamLoadedValue(Op, Expr);
+  }
+
+  return None;
+}
+
 /// Both DefMI and UseMI must be valid.  By default, call directly to the
 /// itinerary. This may be overriden by the target.
 int TargetInstrInfo::getOperandLatency(const InstrItineraryData *ItinData,