--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/config/rs6000/darwin-fallback.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,487 @@
+/* Fallback frame-state unwinder for Darwin.
+   Copyright (C) 2004, 2005, 2007, 2009 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GCC is distributed in the hope that it will be useful, but WITHOUT
+   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+   License for more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifdef __ppc__
+
+#include "tconfig.h"
+#include "tsystem.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "dwarf2.h"
+#include "unwind.h"
+#include "unwind-dw2.h"
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <signal.h>
+
+#define R_LR		65
+#define R_CTR		66
+#define R_CR2		70
+#define R_XER		76
+#define R_VR0		77
+#define R_VRSAVE	109
+#define R_VSCR		110
+#define R_SPEFSCR	112
+
+typedef unsigned long reg_unit;
+
+/* Place in GPRS the parameters to the first 'sc' instruction that would
+   have been executed if we were returning from this CONTEXT, or
+   return false if an unexpected instruction is encountered.  */
+
+static bool
+interpret_libc (reg_unit gprs[32], struct _Unwind_Context *context)
+{
+  uint32_t *pc = (uint32_t *)_Unwind_GetIP (context);
+  uint32_t cr;
+  reg_unit lr = (reg_unit) pc;
+  reg_unit ctr = 0;
+  uint32_t *invalid_address = NULL;
+
+  int i;
+
+  for (i = 0; i < 13; i++)
+    gprs[i] = 1;
+  gprs[1] = _Unwind_GetCFA (context);
+  for (; i < 32; i++)
+    gprs[i] = _Unwind_GetGR (context, i);
+  cr = _Unwind_GetGR (context, R_CR2);
+
+  /* For each supported Libc, we have to track the code flow
+     all the way back into the kernel.
+  
+     This code is believed to support all released Libc/Libsystem builds since
+     Jaguar 6C115, including all the security updates.  To be precise,
+
+     Libc	Libsystem	Build(s)
+     262~1	60~37		6C115
+     262~1	60.2~4		6D52
+     262~1	61~3		6F21-6F22
+     262~1	63~24		6G30-6G37
+     262~1	63~32		6I34-6I35
+     262~1	63~64		6L29-6L60
+     262.4.1~1	63~84		6L123-6R172
+     
+     320~1	71~101		7B85-7D28
+     320~1	71~266		7F54-7F56
+     320~1	71~288		7F112
+     320~1	71~289		7F113
+     320.1.3~1	71.1.1~29	7H60-7H105
+     320.1.3~1	71.1.1~30	7H110-7H113
+     320.1.3~1	71.1.1~31	7H114
+     
+     That's a big table!  It would be insane to try to keep track of
+     every little detail, so we just read the code itself and do what
+     it would do.
+  */
+
+  for (;;)
+    {
+      uint32_t ins = *pc++;
+      
+      if ((ins & 0xFC000003) == 0x48000000)  /* b instruction */
+	{
+	  pc += ((((int32_t) ins & 0x3FFFFFC) ^ 0x2000000) - 0x2000004) / 4;
+	  continue;
+	}
+      if ((ins & 0xFC600000) == 0x2C000000)  /* cmpwi */
+	{
+	  int32_t val1 = (int16_t) ins;
+	  int32_t val2 = gprs[ins >> 16 & 0x1F];
+	  /* Only beq and bne instructions are supported, so we only
+	     need to set the EQ bit.  */
+	  uint32_t mask = 0xF << ((ins >> 21 & 0x1C) ^ 0x1C);
+	  if (val1 == val2)
+	    cr |= mask;
+	  else
+	    cr &= ~mask;
+	  continue;
+	}
+      if ((ins & 0xFEC38003) == 0x40820000)  /* forwards beq/bne */
+	{
+	  if ((cr >> ((ins >> 16 & 0x1F) ^ 0x1F) & 1) == (ins >> 24 & 1))
+	    pc += (ins & 0x7FFC) / 4 - 1;
+	  continue;
+	}
+      if ((ins & 0xFC0007FF) == 0x7C000378) /* or, including mr */
+	{
+	  gprs [ins >> 16 & 0x1F] = (gprs [ins >> 11 & 0x1F] 
+				     | gprs [ins >> 21 & 0x1F]);
+	  continue;
+	}
+      if (ins >> 26 == 0x0E)  /* addi, including li */
+	{
+	  reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
+	  gprs [ins >> 21 & 0x1F] = src + (int16_t) ins;
+	  continue;
+	}
+      if (ins >> 26 == 0x0F)  /* addis, including lis */
+	{
+	  reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
+	  gprs [ins >> 21 & 0x1F] = src + ((int16_t) ins << 16);
+	  continue;
+	}
+      if (ins >> 26 == 0x20)  /* lwz */
+	{
+	  reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
+	  uint32_t *p = (uint32_t *)(src + (int16_t) ins);
+	  if (p == invalid_address)
+	    return false;
+	  gprs [ins >> 21 & 0x1F] = *p;
+	  continue;
+	}
+      if (ins >> 26 == 0x21)  /* lwzu */
+	{
+	  uint32_t *p = (uint32_t *)(gprs [ins >> 16 & 0x1F] += (int16_t) ins);
+	  if (p == invalid_address)
+	    return false;
+	  gprs [ins >> 21 & 0x1F] = *p;
+	  continue;
+	}
+      if (ins >> 26 == 0x24)  /* stw */
+	/* What we hope this is doing is '--in_sigtramp'.  We don't want
+	   to actually store to memory, so just make a note of the
+	   address and refuse to load from it.  */
+	{
+	  reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
+	  uint32_t *p = (uint32_t *)(src + (int16_t) ins);
+	  if (p == NULL || invalid_address != NULL)
+	    return false;
+	  invalid_address = p;
+	  continue;
+	}
+      if (ins >> 26 == 0x2E) /* lmw */
+	{
+	  reg_unit src = (ins >> 16 & 0x1F) == 0 ? 0 : gprs [ins >> 16 & 0x1F];
+	  uint32_t *p = (uint32_t *)(src + (int16_t) ins);
+	  int i;
+
+	  for (i = (ins >> 21 & 0x1F); i < 32; i++)
+	    {
+	      if (p == invalid_address)
+		return false;
+	      gprs[i] = *p++;
+	    }
+	  continue;
+	}
+      if ((ins & 0xFC1FFFFF) == 0x7c0803a6)  /* mtlr */
+	{
+	  lr = gprs [ins >> 21 & 0x1F];
+	  continue;
+	}
+      if ((ins & 0xFC1FFFFF) == 0x7c0802a6)  /* mflr */
+	{
+	  gprs [ins >> 21 & 0x1F] = lr;
+	  continue;
+	}
+      if ((ins & 0xFC1FFFFF) == 0x7c0903a6)  /* mtctr */
+	{
+	  ctr = gprs [ins >> 21 & 0x1F];
+	  continue;
+	}
+      /* The PowerPC User's Manual says that bit 11 of the mtcrf
+	 instruction is reserved and should be set to zero, but it
+	 looks like the Darwin assembler doesn't do that... */
+      if ((ins & 0xFC000FFF) == 0x7c000120) /* mtcrf */
+	{
+	  int i;
+	  uint32_t mask = 0;
+	  for (i = 0; i < 8; i++)
+	    mask |= ((-(ins >> (12 + i) & 1)) & 0xF) << 4 * i;
+	  cr = (cr & ~mask) | (gprs [ins >> 21 & 0x1F] & mask);
+	  continue;
+	}
+      if (ins == 0x429f0005)  /* bcl- 20,4*cr7+so,.+4, loads pc into LR */
+	{
+	  lr = (reg_unit) pc;
+	  continue;
+	}
+      if (ins == 0x4e800420) /* bctr */
+	{
+	  pc = (uint32_t *) ctr;
+	  continue;
+	}
+      if (ins == 0x44000002) /* sc */
+	return true;
+
+      return false;
+    }
+}
+
+/* We used to include <ucontext.h> and <mach/thread_status.h>,
+   but they change so much between different Darwin system versions
+   that it's much easier to just write the structures involved here
+   directly.  */
+
+/* These defines are from the kernel's bsd/dev/ppc/unix_signal.c.  */
+#define UC_TRAD                 1
+#define UC_TRAD_VEC             6
+#define UC_TRAD64               20
+#define UC_TRAD64_VEC           25
+#define UC_FLAVOR               30
+#define UC_FLAVOR_VEC           35
+#define UC_FLAVOR64             40
+#define UC_FLAVOR64_VEC         45
+#define UC_DUAL                 50
+#define UC_DUAL_VEC             55
+
+struct gcc_ucontext 
+{
+  int onstack;
+  sigset_t sigmask;
+  void * stack_sp;
+  size_t stack_sz;
+  int stack_flags;
+  struct gcc_ucontext *link;
+  size_t mcsize;
+  struct gcc_mcontext32 *mcontext;
+};
+
+struct gcc_float_vector_state 
+{
+  double fpregs[32];
+  uint32_t fpscr_pad;
+  uint32_t fpscr;
+  uint32_t save_vr[32][4];
+  uint32_t save_vscr[4];
+};
+
+struct gcc_mcontext32 {
+  uint32_t dar;
+  uint32_t dsisr;
+  uint32_t exception;
+  uint32_t padding1[5];
+  uint32_t srr0;
+  uint32_t srr1;
+  uint32_t gpr[32];
+  uint32_t cr;
+  uint32_t xer;
+  uint32_t lr;
+  uint32_t ctr;
+  uint32_t mq;
+  uint32_t vrsave;
+  struct gcc_float_vector_state fvs;
+};
+
+/* These are based on /usr/include/ppc/ucontext.h and
+   /usr/include/mach/ppc/thread_status.h, but rewritten to be more
+   convenient, to compile on Jaguar, and to work around Radar 3712064
+   on Panther, which is that the 'es' field of 'struct mcontext64' has
+   the wrong type (doh!).  */
+
+struct gcc_mcontext64 {
+  uint64_t dar;
+  uint32_t dsisr;
+  uint32_t exception;
+  uint32_t padding1[4];
+  uint64_t srr0;
+  uint64_t srr1;
+  uint32_t gpr[32][2];
+  uint32_t cr;
+  uint32_t xer[2];  /* These are arrays because the original structure has them misaligned.  */
+  uint32_t lr[2];
+  uint32_t ctr[2];
+  uint32_t vrsave;
+  struct gcc_float_vector_state fvs;
+};
+
+#define UC_FLAVOR_SIZE \
+  (sizeof (struct gcc_mcontext32) - 33*16)
+
+#define UC_FLAVOR_VEC_SIZE (sizeof (struct gcc_mcontext32))
+
+#define UC_FLAVOR64_SIZE \
+  (sizeof (struct gcc_mcontext64) - 33*16)
+
+#define UC_FLAVOR64_VEC_SIZE (sizeof (struct gcc_mcontext64))
+
+/* Given GPRS as input to a 'sc' instruction, and OLD_CFA, update FS
+   to represent the execution of a signal return; or, if not a signal
+   return, return false.  */
+
+static bool
+handle_syscall (_Unwind_FrameState *fs, const reg_unit gprs[32],
+		_Unwind_Ptr old_cfa)
+{
+  struct gcc_ucontext *uctx;
+  bool is_64, is_vector;
+  struct gcc_float_vector_state * float_vector_state;
+  _Unwind_Ptr new_cfa;
+  int i;
+  static _Unwind_Ptr return_addr;
+  
+  /* Yay!  We're in a Libc that we understand, and it's made a
+     system call.  In Jaguar, this is a direct system call with value 103;
+     in Panther and Tiger it is a SYS_syscall call for system call number 184,
+     and in Leopard it is a direct syscall with number 184.  */
+  
+  if (gprs[0] == 0x67 /* SYS_SIGRETURN */)
+    {
+      uctx = (struct gcc_ucontext *) gprs[3];
+      is_vector = (uctx->mcsize == UC_FLAVOR64_VEC_SIZE
+		   || uctx->mcsize == UC_FLAVOR_VEC_SIZE);
+      is_64 = (uctx->mcsize == UC_FLAVOR64_VEC_SIZE
+	       || uctx->mcsize == UC_FLAVOR64_SIZE);
+    }
+  else if (gprs[0] == 0 /* SYS_syscall */ && gprs[3] == 184)
+    {
+      int ctxstyle = gprs[5];
+      uctx = (struct gcc_ucontext *) gprs[4];
+      is_vector = (ctxstyle == UC_FLAVOR_VEC || ctxstyle == UC_FLAVOR64_VEC
+		   || ctxstyle == UC_TRAD_VEC || ctxstyle == UC_TRAD64_VEC);
+      is_64 = (ctxstyle == UC_FLAVOR64_VEC || ctxstyle == UC_TRAD64_VEC
+	       || ctxstyle == UC_FLAVOR64 || ctxstyle == UC_TRAD64);
+    }
+  else if (gprs[0] == 184 /* SYS_sigreturn */)
+    {
+      int ctxstyle = gprs[4];
+      uctx = (struct gcc_ucontext *) gprs[3];
+      is_vector = (ctxstyle == UC_FLAVOR_VEC || ctxstyle == UC_FLAVOR64_VEC
+		   || ctxstyle == UC_TRAD_VEC || ctxstyle == UC_TRAD64_VEC);
+      is_64 = (ctxstyle == UC_FLAVOR64_VEC || ctxstyle == UC_TRAD64_VEC
+	       || ctxstyle == UC_FLAVOR64 || ctxstyle == UC_TRAD64);
+    }
+  else
+    return false;
+
+#define set_offset(r, addr)					\
+  (fs->regs.reg[r].how = REG_SAVED_OFFSET,			\
+   fs->regs.reg[r].loc.offset = (_Unwind_Ptr)(addr) - new_cfa)
+
+  /* Restore even the registers that are not call-saved, since they
+     might be being used in the prologue to save other registers,
+     for instance GPR0 is sometimes used to save LR.  */
+
+  /* Handle the GPRs, and produce the information needed to do the rest.  */
+  if (is_64)
+    {
+      /* The context is 64-bit, but it doesn't carry any extra information
+	 for us because only the low 32 bits of the registers are
+	 call-saved.  */
+      struct gcc_mcontext64 *m64 = (struct gcc_mcontext64 *)uctx->mcontext;
+      int i;
+
+      float_vector_state = &m64->fvs;
+
+      new_cfa = m64->gpr[1][1];
+      
+      set_offset (R_CR2, &m64->cr);
+      for (i = 0; i < 32; i++)
+	set_offset (i, m64->gpr[i] + 1);
+      set_offset (R_XER, m64->xer + 1);
+      set_offset (R_LR, m64->lr + 1);
+      set_offset (R_CTR, m64->ctr + 1);
+      if (is_vector)
+	set_offset (R_VRSAVE, &m64->vrsave);
+      
+      /* Sometimes, srr0 points to the instruction that caused the exception,
+	 and sometimes to the next instruction to be executed; we want
+	 the latter.  */
+      if (m64->exception == 3 || m64->exception == 4
+	  || m64->exception == 6
+	  || (m64->exception == 7 && !(m64->srr1 & 0x10000)))
+	return_addr = m64->srr0 + 4;
+      else
+	return_addr = m64->srr0;
+    }
+  else
+    {
+      struct gcc_mcontext32 *m = uctx->mcontext;
+      int i;
+
+      float_vector_state = &m->fvs;
+      
+      new_cfa = m->gpr[1];
+
+      set_offset (R_CR2, &m->cr);
+      for (i = 0; i < 32; i++)
+	set_offset (i, m->gpr + i);
+      set_offset (R_XER, &m->xer);
+      set_offset (R_LR, &m->lr);
+      set_offset (R_CTR, &m->ctr);
+
+      if (is_vector)
+	set_offset (R_VRSAVE, &m->vrsave);
+
+      /* Sometimes, srr0 points to the instruction that caused the exception,
+	 and sometimes to the next instruction to be executed; we want
+	 the latter.  */
+      if (m->exception == 3 || m->exception == 4
+	  || m->exception == 6
+	  || (m->exception == 7 && !(m->srr1 & 0x10000)))
+	return_addr = m->srr0 + 4;
+      else
+	return_addr = m->srr0;
+    }
+
+  fs->regs.cfa_how = CFA_REG_OFFSET;
+  fs->regs.cfa_reg = STACK_POINTER_REGNUM;
+  fs->regs.cfa_offset = new_cfa - old_cfa;;
+  
+  /* The choice of column for the return address is somewhat tricky.
+     Fortunately, the actual choice is private to this file, and
+     the space it's reserved from is the GCC register space, not the
+     DWARF2 numbering.  So any free element of the right size is an OK
+     choice.  Thus: */
+  fs->retaddr_column = ARG_POINTER_REGNUM;
+  /* FIXME: this should really be done using a DWARF2 location expression,
+     not using a static variable.  In fact, this entire file should
+     be implemented in DWARF2 expressions.  */
+  set_offset (ARG_POINTER_REGNUM, &return_addr);
+
+  for (i = 0; i < 32; i++)
+    set_offset (32 + i, float_vector_state->fpregs + i);
+  set_offset (R_SPEFSCR, &float_vector_state->fpscr);
+  
+  if (is_vector)
+    {
+      for (i = 0; i < 32; i++)
+	set_offset (R_VR0 + i, float_vector_state->save_vr + i);
+      set_offset (R_VSCR, float_vector_state->save_vscr);
+    }
+
+  return true;
+}
+
+/* This is also prototyped in rs6000/darwin.h, inside the
+   MD_FALLBACK_FRAME_STATE_FOR macro.  */
+extern bool _Unwind_fallback_frame_state_for (struct _Unwind_Context *context,
+					      _Unwind_FrameState *fs);
+
+/* Implement the MD_FALLBACK_FRAME_STATE_FOR macro,
+   returning true iff the frame was a sigreturn() frame that we
+   can understand.  */
+
+bool
+_Unwind_fallback_frame_state_for (struct _Unwind_Context *context,
+				  _Unwind_FrameState *fs)
+{
+  reg_unit gprs[32];
+
+  if (!interpret_libc (gprs, context))
+    return false;
+  return handle_syscall (fs, gprs, _Unwind_GetCFA (context));
+}
+#endif