From 5bba08425374ca36fe5fbc7423ce1a09858e4097 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 28 Dec 2010 04:15:37 +0000
Subject: [PATCH] Start adding basic support for emitting the call frame
 instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122590 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/MC/MCDwarf.h        |  4 +++
 lib/MC/MCDwarf.cpp               |  6 +++-
 lib/MC/MCStreamer.cpp            |  9 +++++-
 test/MC/ELF/cfi-def-cfa-offset.s | 49 ++++++++++++++++++++++++++++++++
 4 files changed, 66 insertions(+), 2 deletions(-)
 create mode 100644 test/MC/ELF/cfi-def-cfa-offset.s

diff --git a/include/llvm/MC/MCDwarf.h b/include/llvm/MC/MCDwarf.h
index 303376f16e1..26c28294abe 100644
--- a/include/llvm/MC/MCDwarf.h
+++ b/include/llvm/MC/MCDwarf.h
@@ -16,6 +16,7 @@
 #define LLVM_MC_MCDWARF_H
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/CodeGen/MachineLocation.h" // FIXME
 #include "llvm/MC/MCObjectWriter.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Dwarf.h"
@@ -227,10 +228,13 @@ namespace llvm {
   };
 
   struct MCDwarfFrameInfo {
+    MCDwarfFrameInfo() : Begin(0), End(0), Personality(0), Lsda(0), Moves(),
+                         PersonalityEncoding(0), LsdaEncoding(0) {}
     MCSymbol *Begin;
     MCSymbol *End;
     const MCSymbol *Personality;
     const MCSymbol *Lsda;
+    std::vector<MachineMove> Moves;
     unsigned PersonalityEncoding;
     unsigned LsdaEncoding;
   };
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index cd5141083e3..6e59a58b04d 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -460,9 +460,11 @@ static void EmitFrameMoves(MCStreamer &streamer,
     if (BaseLabel && Label) {
       MCSymbol *ThisSym = Label;
       if (ThisSym != BaseLabel) {
+        // FIXME: We should relax this instead of using a DW_CFA_advance_loc4
+        // for every address change!
         streamer.EmitIntValue(dwarf::DW_CFA_advance_loc4, 1);
         const MCExpr *Length = MakeStartMinusEndExpr(streamer, *BaseLabel,
-                                                     *ThisSym, 4);
+                                                     *ThisSym, 0);
         streamer.EmitValue(Length, 4);
         BaseLabel = ThisSym;
       }
@@ -672,6 +674,8 @@ static MCSymbol *EmitFDE(MCStreamer &streamer,
   streamer.EmitLabel(augmentationEnd);
   // Call Frame Instructions
 
+  EmitFrameMoves(streamer, frame.Moves, frame.Begin, true);
+
   // Padding
   streamer.EmitValueToAlignment(4);
 
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 922a40ce3e7..048e8866bde 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -157,7 +157,7 @@ bool MCStreamer::EmitCFIStartProc() {
     report_fatal_error("Starting a frame before finishing the previous one!");
     return true;
   }
-  MCDwarfFrameInfo Frame = {0, 0, 0, 0, 0, 0};
+  MCDwarfFrameInfo Frame;
   Frame.Begin = getContext().CreateTempSymbol();
   EmitLabel(Frame.Begin);
   FrameInfos.push_back(Frame);
@@ -174,6 +174,13 @@ bool MCStreamer::EmitCFIEndProc() {
 
 bool MCStreamer::EmitCFIDefCfaOffset(int64_t Offset) {
   EnsureValidFrame();
+  MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
+  MCSymbol *Label = getContext().CreateTempSymbol();
+  EmitLabel(Label);
+  MachineLocation Dest(MachineLocation::VirtualFP);
+  MachineLocation Source(MachineLocation::VirtualFP, -Offset);
+  MachineMove Move(Label, Dest, Source);
+  CurFrame->Moves.push_back(Move);
   return false;
 }
 
diff --git a/test/MC/ELF/cfi-def-cfa-offset.s b/test/MC/ELF/cfi-def-cfa-offset.s
new file mode 100644
index 00000000000..b75cc12eafc
--- /dev/null
+++ b/test/MC/ELF/cfi-def-cfa-offset.s
@@ -0,0 +1,49 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump  --dump-section-data | FileCheck %s
+
+f:
+	.cfi_startproc
+	subq	$8, %rsp
+	.cfi_def_cfa_offset 16
+        nop
+	addq	$8, %rsp
+	.cfi_def_cfa_offset 8
+	ret
+	.cfi_endproc
+
+// FIXME: This is a correct but really inefficient coding since
+// we use a CFA_advance_loc4 for every address change!
+
+// CHECK:      # Section 0x00000004
+// CHECK-NEXT: (('sh_name', 0x00000012) # '.eh_frame'
+// CHECK-NEXT:  ('sh_type', 0x00000001)
+// CHECK-NEXT:  ('sh_flags', 0x00000002)
+// CHECK-NEXT:  ('sh_addr', 0x00000000)
+// CHECK-NEXT:  ('sh_offset', 0x00000050)
+// CHECK-NEXT:  ('sh_size', 0x00000038)
+// CHECK-NEXT:  ('sh_link', 0x00000000)
+// CHECK-NEXT:  ('sh_info', 0x00000000)
+// CHECK-NEXT:  ('sh_addralign', 0x00000008)
+// CHECK-NEXT:  ('sh_entsize', 0x00000000)
+// CHECK-NEXT:  ('_section_data', '14000000 00000000 017a5200 01781001 1b0c0708 90010000 1c000000 1c000000 00000000 0a000000 00040400 00000e10 04050000 000e0800')
+// CHECK-NEXT: ),
+
+// CHECK:       # Section 0x00000008
+// CHECK-NEXT: (('sh_name', 0x00000036) # '.rela.eh_frame'
+// CHECK-NEXT:  ('sh_type', 0x00000004)
+// CHECK-NEXT:  ('sh_flags', 0x00000000)
+// CHECK-NEXT:  ('sh_addr', 0x00000000)
+// CHECK-NEXT:  ('sh_offset', 0x00000168)
+// CHECK-NEXT:  ('sh_size', 0x00000018)
+// CHECK-NEXT:  ('sh_link', 0x00000006)
+// CHECK-NEXT:  ('sh_info', 0x00000004)
+// CHECK-NEXT:  ('sh_addralign', 0x00000008)
+// CHECK-NEXT:  ('sh_entsize', 0x00000018)
+// CHECK-NEXT:  ('_relocations', [
+// CHECK-NEXT:   # Relocation 0x00000000
+// CHECK-NEXT:   (('r_offset', 0x00000020)
+// CHECK-NEXT:    ('r_sym', 0x00000002)
+// CHECK-NEXT:    ('r_type', 0x00000002)
+// CHECK-NEXT:    ('r_addend', 0x00000000)
+// CHECK-NEXT:   ),
+// CHECK-NEXT:  ])
+// CHECK-NEXT: ),