Identify end of prologue (and beginning of function body) using DW_LNS_set_prologue_end line table opcode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131194 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 95 insertions, 44 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index fd87224a1e..aa1f6c7535 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1483,12 +1483,17 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
   if (!MI->isDebugValue()) {
     DebugLoc DL = MI->getDebugLoc();
     if (DL != PrevInstLoc && (!DL.isUnknown() || UnknownLocations)) {
+      unsigned Flags = DWARF2_FLAG_IS_STMT;
       PrevInstLoc = DL;
+      if (DL == PrologEndLoc) {
+        Flags |= DWARF2_FLAG_PROLOGUE_END;
+        PrologEndLoc = DebugLoc();
+      }
       if (!DL.isUnknown()) {
         const MDNode *Scope = DL.getScope(Asm->MF->getFunction()->getContext());
-        recordSourceLine(DL.getLine(), DL.getCol(), Scope);
+        recordSourceLine(DL.getLine(), DL.getCol(), Scope, Flags);
       } else
-        recordSourceLine(0, 0, 0);
+        recordSourceLine(0, 0, 0, 0);
     }
   }
 
@@ -1800,21 +1805,6 @@ void DwarfDebug::identifyScopeMarkers() {
   }
 }
 
-/// FindFirstDebugLoc - Find the first debug location in the function. This
-/// is intended to be an approximation for the source position of the
-/// beginning of the function.
-static DebugLoc FindFirstDebugLoc(const MachineFunction *MF) {
-  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
-       I != E; ++I)
-    for (MachineBasicBlock::const_iterator MBBI = I->begin(), MBBE = I->end();
-         MBBI != MBBE; ++MBBI) {
-      DebugLoc DL = MBBI->getDebugLoc();
-      if (!DL.isUnknown())
-        return DL;
-    }
-  return DebugLoc();
-}
-
 /// getScopeNode - Get MDNode for DebugLoc's scope.
 static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
   if (MDNode *InlinedAt = DL.getInlinedAt(Ctx))
@@ -1822,6 +1812,16 @@ static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
   return DL.getScope(Ctx);
 }
 
+/// getFnDebugLoc - Walk up the scope chain of given debug loc and find
+/// line number  info for the function.
+static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
+  const MDNode *Scope = getScopeNode(DL, Ctx);
+  DISubprogram SP = getDISubprogram(Scope);
+  if (SP.Verify()) 
+    return DebugLoc::get(SP.getLineNumber(), 0, SP);
+  return DebugLoc();
+}
+
 /// beginFunction - Gather pre-function debug information.  Assumes being
 /// emitted immediately after the function entry point.
 void DwarfDebug::beginFunction(const MachineFunction *MF) {
@@ -1833,35 +1833,11 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   // Assumes in correct section after the entry point.
   Asm->OutStreamer.EmitLabel(FunctionBeginSym);
 
-  // Emit label for the implicitly defined dbg.stoppoint at the start of the
-  // function.
-  DebugLoc FDL = FindFirstDebugLoc(MF);
-  if (FDL.isUnknown()) return;
-
-  const MDNode *Scope = getScopeNode(FDL, MF->getFunction()->getContext());
-  const MDNode *TheScope = 0;
-
-  DISubprogram SP = getDISubprogram(Scope);
-  unsigned Line, Col;
-  if (SP.Verify()) {
-    Line = SP.getLineNumber();
-    Col = 0;
-    TheScope = SP;
-  } else {
-    Line = FDL.getLine();
-    Col = FDL.getCol();
-    TheScope = Scope;
-  }
-
-  recordSourceLine(Line, Col, TheScope);
-
   assert(UserVariables.empty() && DbgValues.empty() && "Maps weren't cleaned");
 
   /// ProcessedArgs - Collection of arguments already processed.
   SmallPtrSet<const MDNode *, 8> ProcessedArgs;
-
   const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
-
   /// LiveUserVar - Map physreg numbers to the MDNode they contain.
   std::vector<const MDNode*> LiveUserVar(TRI->getNumRegs());
 
@@ -1927,6 +1903,11 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
         if (!MI->isLabel())
           AtBlockEntry = false;
 
+        // First known non DBG_VALUE location marks beginning of function
+        // body.
+        if (PrologEndLoc.isUnknown() && !MI->getDebugLoc().isUnknown())
+          PrologEndLoc = MI->getDebugLoc();
+
         // Check if the instruction clobbers any registers with debug vars.
         for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
                MOE = MI->operands_end(); MOI != MOE; ++MOI) {
@@ -1995,6 +1976,15 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
 
   PrevInstLoc = DebugLoc();
   PrevLabel = FunctionBeginSym;
+
+  // Record beginning of function.
+  if (!PrologEndLoc.isUnknown()) {
+    DebugLoc FnStartDL = getFnDebugLoc(PrologEndLoc,
+                                       MF->getFunction()->getContext());
+    recordSourceLine(FnStartDL.getLine(), FnStartDL.getCol(),
+                     FnStartDL.getScope(MF->getFunction()->getContext()),
+                     DWARF2_FLAG_IS_STMT);
+  }
 }
 
 /// endFunction - Gather and emit post-function debug information.
@@ -2109,7 +2099,8 @@ DbgScope *DwarfDebug::findDbgScope(const MachineInstr *MInsn) {
 /// recordSourceLine - Register a source line with debug info. Returns the
 /// unique label that was emitted and which provides correspondence to
 /// the source line list.
-void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S){
+void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
+                                  unsigned Flags) {
   StringRef Fn;
   StringRef Dir;
   unsigned Src = 1;
@@ -2137,7 +2128,7 @@ void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S){
 
     Src = GetOrCreateSourceID(Fn, Dir);
   }
-  Asm->OutStreamer.EmitDwarfLocDirective(Src, Line, Col, DWARF2_FLAG_IS_STMT,
+  Asm->OutStreamer.EmitDwarfLocDirective(Src, Line, Col, Flags,
                                          0, 0, Fn);
 }
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 4dc9de4e3e..5b29f787df 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -253,6 +253,10 @@ class DwarfDebug {
   DebugLoc PrevInstLoc;
   MCSymbol *PrevLabel;
 
+  /// PrologEndLoc - This location indicates end of function prologue and
+  /// beginning of function body.
+  DebugLoc PrologEndLoc;
+
   struct FunctionDebugFrameInfo {
     unsigned Number;
     std::vector<MachineMove> Moves;
@@ -402,7 +406,8 @@ private:
   /// recordSourceLine - Register a source line with debug info. Returns the
   /// unique label that was emitted and which provides correspondence to
   /// the source line list.
-  void recordSourceLine(unsigned Line, unsigned Col, const MDNode *Scope);
+  void recordSourceLine(unsigned Line, unsigned Col, const MDNode *Scope,
+                        unsigned Flags);
   
   /// recordVariableFrameIndex - Record a variable's index.
   void recordVariableFrameIndex(const DbgVariable *V, int Index);
diff --git a/test/CodeGen/X86/dbg-prolog-end.ll b/test/CodeGen/X86/dbg-prolog-end.ll
new file mode 100644
index 0000000000..81303bb3d2
--- /dev/null
+++ b/test/CodeGen/X86/dbg-prolog-end.ll
@@ -0,0 +1,55 @@
+; RUN: llc -O0 < %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-macosx10.6.7"
+
+;CHECK: .loc	1 2 11 prologue_end
+define i32 @foo(i32 %i) nounwind ssp {
+entry:
+  %i.addr = alloca i32, align 4
+  %j = alloca i32, align 4
+  store i32 %i, i32* %i.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %i.addr}, metadata !7), !dbg !8
+  call void @llvm.dbg.declare(metadata !{i32* %j}, metadata !9), !dbg !11
+  store i32 2, i32* %j, align 4, !dbg !12
+  %tmp = load i32* %j, align 4, !dbg !13
+  %inc = add nsw i32 %tmp, 1, !dbg !13
+  store i32 %inc, i32* %j, align 4, !dbg !13
+  %tmp1 = load i32* %j, align 4, !dbg !14
+  %tmp2 = load i32* %i.addr, align 4, !dbg !14
+  %add = add nsw i32 %tmp1, %tmp2, !dbg !14
+  store i32 %add, i32* %j, align 4, !dbg !14
+  %tmp3 = load i32* %j, align 4, !dbg !15
+  ret i32 %tmp3, !dbg !15
+}
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+define i32 @main() nounwind ssp {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval
+  %call = call i32 @foo(i32 21), !dbg !16
+  ret i32 %call, !dbg !16
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.dbg.sp = !{!1, !6}
+
+!0 = metadata !{i32 589841, i32 0, i32 12, metadata !"/tmp/a.c", metadata !"/private/tmp", metadata !"clang version 3.0 (trunk 131100)", i1 true, i1 false, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
+!1 = metadata !{i32 589870, i32 0, metadata !2, metadata !"foo", metadata !"foo", metadata !"", metadata !2, i32 1, metadata !3, i1 false, i1 true, i32 0, i32 0, i32 0, i32 256, i1 false, i32 (i32)* @foo, null, null} ; [ DW_TAG_subprogram ]
+!2 = metadata !{i32 589865, metadata !"/tmp/a.c", metadata !"/private/tmp", metadata !0} ; [ DW_TAG_file_type ]
+!3 = metadata !{i32 589845, metadata !2, metadata !"", metadata !2, i32 0, i64 0, i64 0, i32 0, i32 0, i32 0, metadata !4, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
+!4 = metadata !{metadata !5}
+!5 = metadata !{i32 589860, metadata !0, metadata !"int", null, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
+!6 = metadata !{i32 589870, i32 0, metadata !2, metadata !"main", metadata !"main", metadata !"", metadata !2, i32 7, metadata !3, i1 false, i1 true, i32 0, i32 0, i32 0, i32 0, i1 false, i32 ()* @main, null, null} ; [ DW_TAG_subprogram ]
+!7 = metadata !{i32 590081, metadata !1, metadata !"i", metadata !2, i32 16777217, metadata !5, i32 0} ; [ DW_TAG_arg_variable ]
+!8 = metadata !{i32 1, i32 13, metadata !1, null}
+!9 = metadata !{i32 590080, metadata !10, metadata !"j", metadata !2, i32 2, metadata !5, i32 0} ; [ DW_TAG_auto_variable ]
+!10 = metadata !{i32 589835, metadata !1, i32 1, i32 16, metadata !2, i32 0} ; [ DW_TAG_lexical_block ]
+!11 = metadata !{i32 2, i32 6, metadata !10, null}
+!12 = metadata !{i32 2, i32 11, metadata !10, null}
+!13 = metadata !{i32 3, i32 2, metadata !10, null}
+!14 = metadata !{i32 4, i32 2, metadata !10, null}
+!15 = metadata !{i32 5, i32 2, metadata !10, null}
+!16 = metadata !{i32 8, i32 2, metadata !17, null}
+!17 = metadata !{i32 589835, metadata !6, i32 7, i32 12, metadata !2, i32 1} ; [ DW_TAG_lexical_block ]