Merge pull request #409 from Alkarex/patch-1
[mono.git] / mono / mini / unwind.c
index 0cd932b90bcabdd3c443be9e0d1d480b62655ecb..2377e0dd009b5e970a01d2732dc2584f943e4458 100644 (file)
  */
 
 #include "mini.h"
-#include "unwind.h"
+#include "mini-unwind.h"
 
-#ifdef __x86_64__
+#include <mono/utils/mono-counters.h>
+#include <mono/utils/freebsd-dwarf.h>
+#include <mono/utils/hazard-pointer.h>
+#include <mono/metadata/threads-types.h>
+#include <mono/metadata/mono-endian.h>
+
+typedef enum {
+       LOC_SAME,
+       LOC_OFFSET
+} LocType;
+
+typedef struct {
+       LocType loc_type;
+       int offset;
+} Loc;
+
+typedef struct {
+       guint32 len;
+       guint8 info [MONO_ZERO_LEN_ARRAY];
+} MonoUnwindInfo;
+
+static CRITICAL_SECTION unwind_mutex;
+
+static MonoUnwindInfo **cached_info;
+static int cached_info_next, cached_info_size;
+static GSList *cached_info_list;
+/* Statistics */
+static int unwind_info_size;
+
+#define unwind_lock() EnterCriticalSection (&unwind_mutex)
+#define unwind_unlock() LeaveCriticalSection (&unwind_mutex)
+
+#ifdef TARGET_AMD64
 static int map_hw_reg_to_dwarf_reg [] = { 0, 2, 1, 3, 7, 6, 4, 5, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
+#define NUM_REGS AMD64_NREG
+#define DWARF_DATA_ALIGN (-8)
+#define DWARF_PC_REG (mono_hw_reg_to_dwarf_reg (AMD64_RIP))
+#elif defined(TARGET_ARM)
+// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0040a/IHI0040A_aadwarf.pdf
+static int map_hw_reg_to_dwarf_reg [] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
+#define NUM_REGS 16
+#define DWARF_DATA_ALIGN (-4)
+#define DWARF_PC_REG (mono_hw_reg_to_dwarf_reg (ARMREG_LR))
+#elif defined (TARGET_X86)
+#ifdef __APPLE__
+/*
+ * LLVM seems to generate unwind info where esp is encoded as 5, and ebp as 4, ie see this line:
+ *   def ESP : RegisterWithSubRegs<"esp", [SP]>, DwarfRegNum<[-2, 5, 4]>;
+ * in lib/Target/X86/X86RegisterInfo.td in the llvm sources.
+ */
+static int map_hw_reg_to_dwarf_reg [] = { 0, 1, 2, 3, 5, 4, 6, 7, 8 };
+#else
+static int map_hw_reg_to_dwarf_reg [] = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };
+#endif
+/* + 1 is for IP */
+#define NUM_REGS X86_NREG + 1
+#define DWARF_DATA_ALIGN (-4)
+#define DWARF_PC_REG (mono_hw_reg_to_dwarf_reg (X86_NREG))
+#elif defined (TARGET_POWERPC)
+// http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html
+static int map_hw_reg_to_dwarf_reg [] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 
+                                                                                 9, 10, 11, 12, 13, 14, 15, 16,
+                                                                                 17, 18, 19, 20, 21, 22, 23, 24,
+                                                                                 25, 26, 27, 28, 29, 30, 31 };
+#define NUM_REGS 110
+#define DWARF_DATA_ALIGN (-(gint32)sizeof (mgreg_t))
+#define DWARF_PC_REG 108
+#elif defined (TARGET_S390X)
+static int map_hw_reg_to_dwarf_reg [] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
+#define NUM_REGS 16
+#define DWARF_DATA_ALIGN (-8)
+#define DWARF_PC_REG (mono_hw_reg_to_dwarf_reg (14))
+#elif defined (TARGET_MIPS)
+/* FIXME: */
+static int map_hw_reg_to_dwarf_reg [32] = {
+       0, 1, 2, 3, 4, 5, 6, 7,
+       8, 9, 10, 11, 12, 13, 14, 15,
+       16, 17, 18, 19, 20, 21, 22, 23,
+       24, 25, 26, 27, 28, 29, 30, 31
+};
+#define NUM_REGS 32
+#define DWARF_DATA_ALIGN (-(gint32)sizeof (mgreg_t))
+#define DWARF_PC_REG (mono_hw_reg_to_dwarf_reg (mips_ra))
+#else
+static int map_hw_reg_to_dwarf_reg [16];
+#define NUM_REGS 16
+#define DWARF_DATA_ALIGN 0
+#define DWARF_PC_REG -1
 #endif
 
+static gboolean dwarf_reg_to_hw_reg_inited;
+
+static int map_dwarf_reg_to_hw_reg [NUM_REGS];
+
 /*
  * mono_hw_reg_to_dwarf_reg:
  *
@@ -22,12 +112,46 @@ static int map_hw_reg_to_dwarf_reg [] = { 0, 2, 1, 3, 7, 6, 4, 5, 8, 9, 10, 11,
 int
 mono_hw_reg_to_dwarf_reg (int reg)
 {
-#ifdef __x86_64__
-       return map_hw_reg_to_dwarf_reg [reg];
-#else
-       g_assert_not_reached ();
-       return -1;
+#ifdef TARGET_POWERPC
+       if (reg == ppc_lr)
+               return 108;
+       else
+               g_assert (reg < NUM_REGS);
+#endif
+
+       if (NUM_REGS == 0) {
+               g_assert_not_reached ();
+               return -1;
+       } else {
+               return map_hw_reg_to_dwarf_reg [reg];
+       }
+}
+
+static void
+init_reg_map (void)
+{
+       int i;
+
+       g_assert (NUM_REGS > 0);
+       for (i = 0; i < sizeof (map_hw_reg_to_dwarf_reg) / sizeof (int); ++i) {
+               map_dwarf_reg_to_hw_reg [mono_hw_reg_to_dwarf_reg (i)] = i;
+       }
+
+#ifdef TARGET_POWERPC
+       map_dwarf_reg_to_hw_reg [DWARF_PC_REG] = ppc_lr;
 #endif
+
+       mono_memory_barrier ();
+       dwarf_reg_to_hw_reg_inited = TRUE;
+}
+
+int
+mono_dwarf_reg_to_hw_reg (int reg)
+{
+       if (!dwarf_reg_to_hw_reg_inited)
+               init_reg_map ();
+
+       return map_dwarf_reg_to_hw_reg [reg];
 }
 
 static G_GNUC_UNUSED void
@@ -46,6 +170,84 @@ encode_uleb128 (guint32 value, guint8 *buf, guint8 **endbuf)
        *endbuf = p;
 }
 
+static G_GNUC_UNUSED void
+encode_sleb128 (gint32 value, guint8 *buf, guint8 **endbuf)
+{
+       gboolean more = 1;
+       gboolean negative = (value < 0);
+       guint32 size = 32;
+       guint8 byte;
+       guint8 *p = buf;
+
+       while (more) {
+               byte = value & 0x7f;
+               value >>= 7;
+               /* the following is unnecessary if the
+                * implementation of >>= uses an arithmetic rather
+                * than logical shift for a signed left operand
+                */
+               if (negative)
+                       /* sign extend */
+                       value |= - (1 <<(size - 7));
+               /* sign bit of byte is second high order bit (0x40) */
+               if ((value == 0 && !(byte & 0x40)) ||
+                       (value == -1 && (byte & 0x40)))
+                       more = 0;
+               else
+                       byte |= 0x80;
+               *p ++= byte;
+       }
+
+       *endbuf = p;
+}
+
+static inline guint32
+decode_uleb128 (guint8 *buf, guint8 **endbuf)
+{
+       guint8 *p = buf;
+       guint32 res = 0;
+       int shift = 0;
+
+       while (TRUE) {
+               guint8 b = *p;
+               p ++;
+
+               res = res | (((int)(b & 0x7f)) << shift);
+               if (!(b & 0x80))
+                       break;
+               shift += 7;
+       }
+
+       *endbuf = p;
+
+       return res;
+}
+
+static inline gint32
+decode_sleb128 (guint8 *buf, guint8 **endbuf)
+{
+       guint8 *p = buf;
+       gint32 res = 0;
+       int shift = 0;
+
+       while (TRUE) {
+               guint8 b = *p;
+               p ++;
+
+               res = res | (((int)(b & 0x7f)) << shift);
+               shift += 7;
+               if (!(b & 0x80)) {
+                       if (shift < 32 && (b & 0x40))
+                               res |= - (1 << shift);
+                       break;
+               }
+       }
+
+       *endbuf = p;
+
+       return res;
+}
+
 /*
  * mono_unwind_ops_encode:
  *
@@ -60,7 +262,7 @@ mono_unwind_ops_encode (GSList *unwind_ops, guint32 *out_len)
        int loc;
        guint8 *buf, *p, *res;
 
-       p = buf = g_malloc0 (256);
+       p = buf = g_malloc0 (4096);
 
        loc = 0;
        l = unwind_ops;
@@ -73,9 +275,14 @@ mono_unwind_ops_encode (GSList *unwind_ops, guint32 *out_len)
                reg = mono_hw_reg_to_dwarf_reg (op->reg);
 
                /* Emit an advance_loc if neccesary */
-               if (op->when > loc) {
-                       g_assert (op->when - loc < 32);
-                       *p ++ = DW_CFA_advance_loc | (op->when - loc);
+               while (op->when > loc) {
+                       if (op->when - loc < 32) {
+                               *p ++ = DW_CFA_advance_loc | (op->when - loc);
+                               loc = op->when;
+                       } else {
+                               *p ++ = DW_CFA_advance_loc | (30);
+                               loc += 30;
+                       }
                }                       
 
                switch (op->op) {
@@ -93,21 +300,761 @@ mono_unwind_ops_encode (GSList *unwind_ops, guint32 *out_len)
                        encode_uleb128 (reg, p, &p);
                        break;
                case DW_CFA_offset:
-                       *p ++ = DW_CFA_offset | reg;
-                       encode_uleb128 (op->val / - 8, p, &p);
+                       if (reg > 63) {
+                               *p ++ = DW_CFA_offset_extended_sf;
+                               encode_uleb128 (reg, p, &p);
+                               encode_sleb128 (op->val / DWARF_DATA_ALIGN, p, &p);
+                       } else {
+                               *p ++ = DW_CFA_offset | reg;
+                               encode_uleb128 (op->val / DWARF_DATA_ALIGN, p, &p);
+                       }
                        break;
                default:
                        g_assert_not_reached ();
                        break;
                }
-
-               loc = op->when;
        }
        
-       g_assert (p - buf < 256);
+       g_assert (p - buf < 4096);
        *out_len = p - buf;
        res = g_malloc (p - buf);
        memcpy (res, buf, p - buf);
        g_free (buf);
        return res;
 }
+
+#if 0
+#define UNW_DEBUG(stmt) do { stmt; } while (0)
+#else
+#define UNW_DEBUG(stmt) do { } while (0)
+#endif
+
+static G_GNUC_UNUSED void
+print_dwarf_state (int cfa_reg, int cfa_offset, int ip, int nregs, Loc *locations)
+{
+       int i;
+
+       printf ("\t%x: cfa=r%d+%d ", ip, cfa_reg, cfa_offset);
+
+       for (i = 0; i < nregs; ++i)
+               if (locations [i].loc_type == LOC_OFFSET)
+                       printf ("r%d@%d(cfa) ", i, locations [i].offset);
+       printf ("\n");
+}
+
+/*
+ * Given the state of the current frame as stored in REGS, execute the unwind 
+ * operations in unwind_info until the location counter reaches POS. The result is 
+ * stored back into REGS. OUT_CFA will receive the value of the CFA.
+ * If SAVE_LOCATIONS is non-NULL, it should point to an array of size SAVE_LOCATIONS_LEN.
+ * On return, the nth entry will point to the address of the stack slot where register
+ * N was saved, or NULL, if it was not saved by this frame.
+ * This function is signal safe.
+ */
+void
+mono_unwind_frame (guint8 *unwind_info, guint32 unwind_info_len, 
+                                  guint8 *start_ip, guint8 *end_ip, guint8 *ip, mgreg_t *regs, int nregs,
+                                  mgreg_t **save_locations, int save_locations_len,
+                                  guint8 **out_cfa)
+{
+       Loc locations [NUM_REGS];
+       int i, pos, reg, cfa_reg, cfa_offset;
+       guint8 *p;
+       guint8 *cfa_val;
+
+       for (i = 0; i < NUM_REGS; ++i)
+               locations [i].loc_type = LOC_SAME;
+
+       p = unwind_info;
+       pos = 0;
+       cfa_reg = -1;
+       cfa_offset = -1;
+       while (pos <= ip - start_ip && p < unwind_info + unwind_info_len) {
+               int op = *p & 0xc0;
+
+               switch (op) {
+               case DW_CFA_advance_loc:
+                       UNW_DEBUG (print_dwarf_state (cfa_reg, cfa_offset, pos, nregs, locations));
+                       pos += *p & 0x3f;
+                       p ++;
+                       break;
+               case DW_CFA_offset:
+                       reg = *p & 0x3f;
+                       p ++;
+                       locations [reg].loc_type = LOC_OFFSET;
+                       locations [reg].offset = decode_uleb128 (p, &p) * DWARF_DATA_ALIGN;
+                       break;
+               case 0: {
+                       int ext_op = *p;
+                       p ++;
+                       switch (ext_op) {
+                       case DW_CFA_def_cfa:
+                               cfa_reg = decode_uleb128 (p, &p);
+                               cfa_offset = decode_uleb128 (p, &p);
+                               break;
+                       case DW_CFA_def_cfa_offset:
+                               cfa_offset = decode_uleb128 (p, &p);
+                               break;
+                       case DW_CFA_def_cfa_register:
+                               cfa_reg = decode_uleb128 (p, &p);
+                               break;
+                       case DW_CFA_offset_extended_sf:
+                               reg = decode_uleb128 (p, &p);
+                               locations [reg].loc_type = LOC_OFFSET;
+                               locations [reg].offset = decode_sleb128 (p, &p) * DWARF_DATA_ALIGN;
+                               break;
+                       case DW_CFA_advance_loc4:
+                               pos += read32 (p);
+                               p += 4;
+                               break;
+                       default:
+                               g_assert_not_reached ();
+                       }
+                       break;
+               }
+               default:
+                       g_assert_not_reached ();
+               }
+       }
+
+       if (save_locations)
+               memset (save_locations, 0, save_locations_len * sizeof (mgreg_t*));
+
+       cfa_val = (guint8*)regs [mono_dwarf_reg_to_hw_reg (cfa_reg)] + cfa_offset;
+       for (i = 0; i < NUM_REGS; ++i) {
+               if (locations [i].loc_type == LOC_OFFSET) {
+                       int hreg = mono_dwarf_reg_to_hw_reg (i);
+                       g_assert (hreg < nregs);
+                       regs [hreg] = *(mgreg_t*)(cfa_val + locations [i].offset);
+                       if (save_locations && hreg < save_locations_len)
+                               save_locations [hreg] = (mgreg_t*)(cfa_val + locations [i].offset);
+               }
+       }
+
+       *out_cfa = cfa_val;
+}
+
+void
+mono_unwind_init (void)
+{
+       InitializeCriticalSection (&unwind_mutex);
+
+       mono_counters_register ("Unwind info size", MONO_COUNTER_JIT | MONO_COUNTER_INT, &unwind_info_size);
+}
+
+void
+mono_unwind_cleanup (void)
+{
+       int i;
+
+       DeleteCriticalSection (&unwind_mutex);
+
+       if (!cached_info)
+               return;
+
+       for (i = 0; i < cached_info_next; ++i) {
+               MonoUnwindInfo *cached = cached_info [i];
+
+               g_free (cached);
+       }
+
+       g_free (cached_info);
+}
+
+/*
+ * mono_cache_unwind_info
+ *
+ *   Save UNWIND_INFO in the unwind info cache and return an id which can be passed
+ * to mono_get_cached_unwind_info to get a cached copy of the info.
+ * A copy is made of the unwind info.
+ * This function is useful for two reasons:
+ * - many methods have the same unwind info
+ * - MonoJitInfo->used_regs is an int so it can't store the pointer to the unwind info
+ */
+guint32
+mono_cache_unwind_info (guint8 *unwind_info, guint32 unwind_info_len)
+{
+       int i;
+       MonoUnwindInfo *info;
+
+       unwind_lock ();
+
+       if (cached_info == NULL) {
+               cached_info_size = 16;
+               cached_info = g_new0 (MonoUnwindInfo*, cached_info_size);
+       }
+
+       for (i = 0; i < cached_info_next; ++i) {
+               MonoUnwindInfo *cached = cached_info [i];
+
+               if (cached->len == unwind_info_len && memcmp (cached->info, unwind_info, unwind_info_len) == 0) {
+                       unwind_unlock ();
+                       return i;
+               }
+       }
+
+       info = g_malloc (sizeof (MonoUnwindInfo) + unwind_info_len);
+       info->len = unwind_info_len;
+       memcpy (&info->info, unwind_info, unwind_info_len);
+
+       i = cached_info_next;
+       
+       if (cached_info_next >= cached_info_size) {
+               MonoUnwindInfo **old_table, **new_table;
+
+               /*
+                * Avoid freeing the old table so mono_get_cached_unwind_info ()
+                * doesn't need locks/hazard pointers.
+                */
+
+               old_table = cached_info;
+               new_table = g_new0 (MonoUnwindInfo*, cached_info_size * 2);
+
+               memcpy (new_table, cached_info, cached_info_size * sizeof (MonoUnwindInfo*));
+
+               mono_memory_barrier ();
+
+               cached_info = new_table;
+
+               cached_info_list = g_slist_prepend (cached_info_list, cached_info);
+
+               cached_info_size *= 2;
+       }
+
+       cached_info [cached_info_next ++] = info;
+
+       unwind_info_size += sizeof (MonoUnwindInfo) + unwind_info_len;
+
+       unwind_unlock ();
+       return i;
+}
+
+/*
+ * This function is signal safe.
+ */
+guint8*
+mono_get_cached_unwind_info (guint32 index, guint32 *unwind_info_len)
+{
+       MonoUnwindInfo **table;
+       MonoUnwindInfo *info;
+       guint8 *data;
+
+       /*
+        * This doesn't need any locks/hazard pointers,
+        * since new tables are copies of the old ones.
+        */
+       table = cached_info;
+
+       info = table [index];
+
+       *unwind_info_len = info->len;
+       data = info->info;
+
+       return data;
+}
+
+/*
+ * mono_unwind_get_dwarf_data_align:
+ *
+ *   Return the data alignment used by the encoded unwind information.
+ */
+int
+mono_unwind_get_dwarf_data_align (void)
+{
+       return DWARF_DATA_ALIGN;
+}
+
+/*
+ * mono_unwind_get_dwarf_pc_reg:
+ *
+ *   Return the dwarf register number of the register holding the ip of the
+ * previous frame.
+ */
+int
+mono_unwind_get_dwarf_pc_reg (void)
+{
+       return DWARF_PC_REG;
+}
+
+static void
+decode_cie_op (guint8 *p, guint8 **endp)
+{
+       int op = *p & 0xc0;
+
+       switch (op) {
+       case DW_CFA_advance_loc:
+               p ++;
+               break;
+       case DW_CFA_offset:
+               p ++;
+               decode_uleb128 (p, &p);
+               break;
+       case 0: {
+               int ext_op = *p;
+               p ++;
+               switch (ext_op) {
+               case DW_CFA_def_cfa:
+                       decode_uleb128 (p, &p);
+                       decode_uleb128 (p, &p);
+                       break;
+               case DW_CFA_def_cfa_offset:
+                       decode_uleb128 (p, &p);
+                       break;
+               case DW_CFA_def_cfa_register:
+                       decode_uleb128 (p, &p);
+                       break;
+               case DW_CFA_advance_loc4:
+                       p += 4;
+                       break;
+               case DW_CFA_offset_extended_sf:
+                       decode_uleb128 (p, &p);
+                       decode_uleb128 (p, &p);
+                       break;
+               default:
+                       g_assert_not_reached ();
+               }
+               break;
+       }
+       default:
+               g_assert_not_reached ();
+       }
+
+       *endp = p;
+}
+
+static gint64
+read_encoded_val (guint32 encoding, guint8 *p, guint8 **endp)
+{
+       gint64 res;
+
+       switch (encoding & 0xf) {
+       case DW_EH_PE_sdata8:
+               res = *(gint64*)p;
+               p += 8;
+               break;
+       case DW_EH_PE_sdata4:
+               res = *(gint32*)p;
+               p += 4;
+               break;
+       default:
+               g_assert_not_reached ();
+       }
+
+       *endp = p;
+       return res;
+}
+
+/*
+ * decode_lsda:
+ *
+ *   Decode the Language Specific Data Area generated by LLVM.
+ */
+static void
+decode_lsda (guint8 *lsda, guint8 *code, MonoJitExceptionInfo **ex_info, guint32 *ex_info_len, gpointer **type_info, int *this_reg, int *this_offset)
+{
+       gint32 ttype_offset, call_site_length;
+       gint32 ttype_encoding, call_site_encoding;
+       guint8 *ttype, *action_table, *call_site, *p;
+       int i, ncall_sites;
+
+       /*
+        * LLVM generates a c++ style LSDA, which can be decoded by looking at
+        * eh_personality.cc in gcc.
+        */
+       p = lsda;
+
+       if (*p == DW_EH_PE_udata4) {
+               /* This is the modified LSDA generated by the LLVM mono branch */
+               guint32 mono_magic, version;
+               gint32 op, reg, offset;
+
+               p ++;
+               mono_magic = decode_uleb128 (p, &p);
+               g_assert (mono_magic == 0x4d4fef4f);
+               version = decode_uleb128 (p, &p);
+               g_assert (version == 1);
+
+               /* 'this' location */
+               op = *p;
+               g_assert (op == DW_OP_bregx);
+               p ++;
+               reg = decode_uleb128 (p, &p);
+               offset = decode_sleb128 (p, &p);
+
+               *this_reg = mono_dwarf_reg_to_hw_reg (reg);
+               *this_offset = offset;
+       } else {
+               /* Read @LPStart */
+               g_assert (*p == DW_EH_PE_omit);
+               p ++;
+
+               *this_reg = -1;
+               *this_offset = -1;
+       }
+
+       /* Read @TType */
+       ttype_encoding = *p;
+       p ++;
+       ttype_offset = decode_uleb128 (p, &p);
+       ttype = p + ttype_offset;
+
+       /* Read call-site table */
+       call_site_encoding = *p;
+       g_assert (call_site_encoding == DW_EH_PE_udata4);
+       p ++;
+       call_site_length = decode_uleb128 (p, &p);
+       call_site = p;
+       p += call_site_length;
+       action_table = p;
+
+       /* Calculate the size of our table */
+       ncall_sites = 0;
+       p = call_site;
+       while (p < action_table) {
+               int block_start_offset, block_size, landing_pad, action_offset;
+
+               block_start_offset = read32 (p);
+               p += sizeof (gint32);
+               block_size = read32 (p);
+               p += sizeof (gint32);
+               landing_pad = read32 (p);
+               p += sizeof (gint32);
+               action_offset = decode_uleb128 (p, &p);
+
+               /* landing_pad == 0 means the region has no landing pad */
+               if (landing_pad)
+                       ncall_sites ++;
+       }
+
+       if (ex_info) {
+               *ex_info = g_malloc0 (ncall_sites * sizeof (MonoJitExceptionInfo));
+               *ex_info_len = ncall_sites;
+       }
+
+       if (type_info)
+               *type_info = g_malloc0 (ncall_sites * sizeof (gpointer));
+
+       p = call_site;
+       i = 0;
+       while (p < action_table) {
+               int block_start_offset, block_size, landing_pad, action_offset, type_offset;
+               guint8 *action, *tinfo;
+
+               block_start_offset = read32 (p);
+               p += sizeof (gint32);
+               block_size = read32 (p);
+               p += sizeof (gint32);
+               landing_pad = read32 (p);
+               p += sizeof (gint32);
+               action_offset = decode_uleb128 (p, &p);
+
+               if (!action_offset)
+                       continue;
+
+               action = action_table + action_offset - 1;
+
+               type_offset = decode_sleb128 (action, &action);
+
+               if (landing_pad) {
+                       //printf ("BLOCK: %p-%p %p, %d\n", code + block_start_offset, code + block_start_offset + block_size, code + landing_pad, action_offset);
+
+                       g_assert (ttype_offset);
+
+                       if (ttype_encoding == DW_EH_PE_absptr) {
+                               guint8 *ttype_entry = (ttype - (type_offset * sizeof (gpointer)));
+                               tinfo = *(gpointer*)ttype_entry;
+                       } else if (ttype_encoding == (DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4)) {
+                               guint8 *ttype_entry = (ttype - (type_offset * 4));
+                               gint32 offset = *(gint32*)ttype_entry;
+                               guint8 *stub = ttype_entry + offset;
+                               tinfo = *(gpointer*)stub;
+                       } else if (ttype_encoding == (DW_EH_PE_pcrel | DW_EH_PE_sdata4)) {
+                               guint8 *ttype_entry = (ttype - (type_offset * 4));
+                               gint32 offset = *(gint32*)ttype_entry;
+                               tinfo = ttype_entry + offset;
+                       } else if (ttype_encoding == DW_EH_PE_udata4) {
+                               /* Embedded directly */
+                               guint8 *ttype_entry = (ttype - (type_offset * 4));
+                               tinfo = ttype_entry;
+                       } else {
+                               g_assert_not_reached ();
+                       }
+
+                       if (ex_info) {
+                               if (*type_info)
+                                       (*type_info) [i] = tinfo;
+                               (*ex_info)[i].try_start = code + block_start_offset;
+                               (*ex_info)[i].try_end = code + block_start_offset + block_size;
+                               (*ex_info)[i].handler_start = code + landing_pad;
+
+                       }
+                       i ++;
+               }
+       }
+}
+
+/*
+ * mono_unwind_decode_fde:
+ *
+ *   Decode a DWARF FDE entry, returning the unwind opcodes.
+ * If not NULL, EX_INFO is set to a malloc-ed array of MonoJitExceptionInfo structures,
+ * only try_start, try_end and handler_start is set.
+ * If not NULL, TYPE_INFO is set to a malloc-ed array containing the ttype table from the
+ * LSDA.
+ */
+guint8*
+mono_unwind_decode_fde (guint8 *fde, guint32 *out_len, guint32 *code_len, MonoJitExceptionInfo **ex_info, guint32 *ex_info_len, gpointer **type_info, int *this_reg, int *this_offset)
+{
+       guint8 *p, *cie, *fde_current, *fde_aug = NULL, *code, *fde_cfi, *cie_cfi;
+       gint32 fde_len, cie_offset, pc_begin, pc_range, aug_len, fde_data_len;
+       gint32 cie_len, cie_id, cie_version, code_align, data_align, return_reg;
+       gint32 i, cie_aug_len, buf_len;
+       char *cie_aug_str;
+       guint8 *buf;
+       gboolean has_fde_augmentation = FALSE;
+
+       /* 
+        * http://refspecs.freestandards.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
+        */
+
+       *type_info = NULL;
+       *this_reg = -1;
+       *this_offset = -1;
+
+       /* Decode FDE */
+
+       p = fde;
+       // FIXME: Endianess ?
+       fde_len = *(guint32*)p;
+       g_assert (fde_len != 0xffffffff && fde_len != 0);
+       p += 4;
+       cie_offset = *(guint32*)p;
+       cie = p - cie_offset;
+       p += 4;
+       fde_current = p;
+
+       /* Decode CIE */
+       p = cie;
+       cie_len = *(guint32*)p;
+       p += 4;
+       cie_id = *(guint32*)p;
+       g_assert (cie_id == 0);
+       p += 4;
+       cie_version = *p;
+       g_assert (cie_version == 1);
+       p += 1;
+       cie_aug_str = (char*)p;
+       p += strlen (cie_aug_str) + 1;
+       code_align = decode_uleb128 (p, &p);
+       data_align = decode_sleb128 (p, &p);
+       return_reg = decode_uleb128 (p, &p);
+       if (strstr (cie_aug_str, "z")) {
+               guint8 *cie_aug;
+               guint32 p_encoding;
+
+               cie_aug_len = decode_uleb128 (p, &p);
+
+               has_fde_augmentation = TRUE;
+
+               cie_aug = p;
+               for (i = 0; cie_aug_str [i] != '\0'; ++i) {
+                       switch (cie_aug_str [i]) {
+                       case 'z':
+                               break;
+                       case 'P':
+                               p_encoding = *p;
+                               p ++;
+                               read_encoded_val (p_encoding, p, &p);
+                               break;
+                       case 'L':
+                               g_assert ((*p == (DW_EH_PE_sdata4|DW_EH_PE_pcrel)) || (*p == (DW_EH_PE_sdata8|DW_EH_PE_pcrel)));
+                               p ++;
+                               break;
+                       case 'R':
+                               g_assert (*p == (DW_EH_PE_sdata4|DW_EH_PE_pcrel));
+                               p ++;
+                               break;
+                       default:
+                               g_assert_not_reached ();
+                               break;
+                       }
+               }
+                       
+               p = cie_aug;
+               p += cie_aug_len;
+       }
+       cie_cfi = p;
+
+       /* Continue decoding FDE */
+       p = fde_current;
+       /* DW_EH_PE_sdata4|DW_EH_PE_pcrel encoding */
+       pc_begin = *(gint32*)p;
+       code = p + pc_begin;
+       p += 4;
+       pc_range = *(guint32*)p;
+       p += 4;
+       if (has_fde_augmentation) {
+               aug_len = decode_uleb128 (p, &p);
+               fde_aug = p;
+               p += aug_len;
+       } else {
+               aug_len = 0;
+       }
+       fde_cfi = p;
+       fde_data_len = fde + 4 + fde_len - p;
+
+       if (code_len)
+               *code_len = pc_range;
+
+       if (ex_info) {
+               *ex_info = NULL;
+               *ex_info_len = 0;
+       }
+
+       /* Decode FDE augmention */
+       if (aug_len) {
+               gint32 lsda_offset;
+               guint8 *lsda;
+
+               /* sdata|pcrel encoding */
+               if (aug_len == 4)
+                       lsda_offset = read32 (fde_aug);
+               else if (aug_len == 8)
+                       lsda_offset = *(gint64*)fde_aug;
+               else
+                       g_assert_not_reached ();
+               if (lsda_offset != 0) {
+                       lsda = fde_aug + lsda_offset;
+
+                       decode_lsda (lsda, code, ex_info, ex_info_len, type_info, this_reg, this_offset);
+               }
+       }
+
+       /* Make sure the FDE uses the same constants as we do */
+       g_assert (code_align == 1);
+       g_assert (data_align == DWARF_DATA_ALIGN);
+       g_assert (return_reg == DWARF_PC_REG);
+
+       buf_len = (cie + cie_len + 4 - cie_cfi) + (fde + fde_len + 4 - fde_cfi);
+       buf = g_malloc0 (buf_len);
+
+       i = 0;
+       p = cie_cfi;
+       while (p < cie + cie_len + 4) {
+               if (*p == DW_CFA_nop)
+                       break;
+               else
+                       decode_cie_op (p, &p);
+       }
+       memcpy (buf + i, cie_cfi, p - cie_cfi);
+       i += p - cie_cfi;
+
+       p = fde_cfi;
+       while (p < fde + fde_len + 4) {
+               if (*p == DW_CFA_nop)
+                       break;
+               else
+                       decode_cie_op (p, &p);
+       }
+       memcpy (buf + i, fde_cfi, p - fde_cfi);
+       i += p - fde_cfi;
+       g_assert (i <= buf_len);
+
+       *out_len = i;
+
+       return g_realloc (buf, i);
+}
+
+/*
+ * mono_unwind_decode_mono_fde:
+ *
+ *   Decode an FDE entry in the LLVM emitted mono EH frame.
+ * info->ex_info is set to a malloc-ed array of MonoJitExceptionInfo structures,
+ * only try_start, try_end and handler_start is set.
+ * info->type_info is set to a malloc-ed array containing the ttype table from the
+ * LSDA.
+ */
+void
+mono_unwind_decode_llvm_mono_fde (guint8 *fde, int fde_len, guint8 *cie, guint8 *code, MonoLLVMFDEInfo *res)
+{
+       guint8 *p, *fde_aug, *cie_cfi, *fde_cfi, *buf;
+       int has_aug, aug_len, cie_cfi_len, fde_cfi_len;
+       gint32 code_align, data_align, return_reg, pers_encoding;
+
+       memset (res, 0, sizeof (*res));
+       res->this_reg = -1;
+       res->this_offset = -1;
+
+       /* fde points to data emitted by LLVM in DwarfException::EmitMonoEHFrame () */
+       p = fde;
+       has_aug = *p;
+       p ++;
+       if (has_aug) {
+               aug_len = read32 (p);
+               p += 4;
+       } else {
+               aug_len = 0;
+       }
+       fde_aug = p;
+       p += aug_len;
+       fde_cfi = p;
+
+       if (has_aug) {
+               guint8 *lsda;
+
+               /* The LSDA is embedded directly into the FDE */
+               lsda = fde_aug;
+
+               decode_lsda (lsda, code, &res->ex_info, &res->ex_info_len, &res->type_info, &res->this_reg, &res->this_offset);
+       }
+
+       /* Decode CIE */
+       p = cie;
+       code_align = decode_uleb128 (p, &p);
+       data_align = decode_sleb128 (p, &p);
+       return_reg = decode_uleb128 (p, &p);
+       pers_encoding = *p;
+       p ++;
+       if (pers_encoding != DW_EH_PE_omit)
+               read_encoded_val (pers_encoding, p, &p);
+
+       cie_cfi = p;
+
+       /* Make sure the FDE uses the same constants as we do */
+       g_assert (code_align == 1);
+       g_assert (data_align == DWARF_DATA_ALIGN);
+       g_assert (return_reg == DWARF_PC_REG);
+
+       /* Compute size of CIE unwind info it is DW_CFA_nop terminated */
+       p = cie_cfi;
+       while (TRUE) {
+               if (*p == DW_CFA_nop)
+                       break;
+               else
+                       decode_cie_op (p, &p);
+       }
+       cie_cfi_len = p - cie_cfi;
+       fde_cfi_len = (fde + fde_len - fde_cfi);
+
+       buf = g_malloc0 (cie_cfi_len + fde_cfi_len);
+       memcpy (buf, cie_cfi, cie_cfi_len);
+       memcpy (buf + cie_cfi_len, fde_cfi, fde_cfi_len);
+
+       res->unw_info_len = cie_cfi_len + fde_cfi_len;
+       res->unw_info = buf;
+}
+
+/*
+ * mono_unwind_get_cie_program:
+ *
+ *   Get the unwind bytecode for the DWARF CIE.
+ */
+GSList*
+mono_unwind_get_cie_program (void)
+{
+#if defined(TARGET_AMD64) || defined(TARGET_X86) || defined(TARGET_POWERPC)
+       return mono_arch_get_cie_program ();
+#else
+       return NULL;
+#endif
+}