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--- valgrind/coregrind/m_debuginfo/readdwarf.c.jj	2009-07-13 14:09:14.478329957 +0200
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+++ valgrind/coregrind/m_debuginfo/readdwarf.c	2009-07-13 15:18:35.596080042 +0200
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@@ -1923,6 +1923,11 @@ static void ppRegRule ( XArray* exprs, R
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 }
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+/* Size of the stack of register unwind rules.  This is only
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+   exceedingly rarely used, so a stack of size 1 should actually work
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+   with almost all compiler-generated CFA. */
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+#define N_RR_STACK 4
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+
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 typedef
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    struct {
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       /* Read-only fields (set by the CIE) */
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@@ -1939,8 +1944,12 @@ typedef
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       Int     cfa_reg;
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       Int     cfa_off;  /* in bytes */
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       Int     cfa_expr_ix; /* index into cfa_exprs */
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-      /* register unwind rules */
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-      RegRule reg[N_CFI_REGS];
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+      /* A stack of register unwind rules.  We need a stack of them,
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+         rather than just one set of rules, in order to handle
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+         DW_CFA_{remember,restore}_state. */
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+      RegRule reg[N_RR_STACK][N_CFI_REGS];
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+      Int     reg_sp; /* 0 <= reg_sp < N_RR_STACK; points at the
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+                         currently-in-use rule set. */
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       /* array of CfiExpr, shared by reg[] and cfa_expr_ix */
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       XArray* exprs;
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    }
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@@ -1948,7 +1957,7 @@ typedef
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 static void ppUnwindContext ( UnwindContext* ctx )
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 {
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-   Int i;
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+   Int j, i;
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    VG_(printf)("0x%llx: ", (ULong)ctx->loc);
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    if (ctx->cfa_is_regoff) {
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       VG_(printf)("%d(r%d) ",  ctx->cfa_off, ctx->cfa_reg);
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@@ -1958,14 +1967,19 @@ static void ppUnwindContext ( UnwindCont
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       ML_(ppCfiExpr)( ctx->exprs, ctx->cfa_expr_ix );
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       VG_(printf)("} ");
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    }
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-   for (i = 0; i < N_CFI_REGS; i++)
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-      ppRegRule(ctx->exprs, &ctx->reg[i]);
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+   for (j = 0; j <= ctx->reg_sp; j++) {
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+      VG_(printf)("%s[%d]={ ", j > 0 ? " " : "", j);
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+      for (i = 0; i < N_CFI_REGS; i++)
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+         ppRegRule(ctx->exprs, &ctx->reg[j][i]);
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+      VG_(printf)("}");
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+   }
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    VG_(printf)("\n");
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 }
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 static void initUnwindContext ( /*OUT*/UnwindContext* ctx )
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 {
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-   Int i;
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+   Int j, i;
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+   VG_(memset)(ctx, 0, sizeof(*ctx));
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    ctx->code_a_f      = 0;
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    ctx->data_a_f      = 0;
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    ctx->initloc       = 0;
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@@ -1976,9 +1990,12 @@ static void initUnwindContext ( /*OUT*/U
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    ctx->cfa_off       = 0;
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    ctx->cfa_expr_ix   = 0;
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    ctx->exprs         = NULL;
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-   for (i = 0; i < N_CFI_REGS; i++) {
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-      ctx->reg[i].tag = RR_Undef;
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-      ctx->reg[i].arg = 0;
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+   ctx->reg_sp        = 0;
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+   for (j = 0; j < N_RR_STACK; j++) {
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+      for (i = 0; i < N_CFI_REGS; i++) {
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+         ctx->reg[j][i].tag = RR_Undef;
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+         ctx->reg[j][i].arg = 0;
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+      }
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    }
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 }
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@@ -2104,8 +2121,15 @@ static Bool summarise_context( /*OUT*/Di
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          why = 2; goto failed; /* otherwise give up */        \
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    }
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-   SUMMARISE_HOW(si->ra_how, si->ra_off, ctx->reg[ctx->ra_reg] );
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-   SUMMARISE_HOW(si->fp_how, si->fp_off, ctx->reg[FP_REG] );
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+   /* Guard against obviously stupid settings of the reg-rule stack
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+      pointer. */
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+   if (ctx->reg_sp < 0)           { why = 8; goto failed; }
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+   if (ctx->reg_sp >= N_RR_STACK) { why = 9; goto failed; }
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+
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+   SUMMARISE_HOW(si->ra_how, si->ra_off,
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+                             ctx->reg[ctx->reg_sp][ctx->ra_reg] );
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+   SUMMARISE_HOW(si->fp_how, si->fp_off,
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+                             ctx->reg[ctx->reg_sp][FP_REG] );
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 #  undef SUMMARISE_HOW
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@@ -2116,7 +2140,7 @@ static Bool summarise_context( /*OUT*/Di
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    /* also, gcc says "Undef" for %{e,r}bp when it is unchanged.  So
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       .. */
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-   if (ctx->reg[FP_REG].tag == RR_Undef)
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+   if (ctx->reg[ctx->reg_sp][FP_REG].tag == RR_Undef)
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       si->fp_how = CFIR_SAME;
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    /* knock out some obviously stupid cases */
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@@ -2215,10 +2239,10 @@ static void ppUnwindContext_summary ( Un
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    }
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    VG_(printf)("RA=");
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-   ppRegRule( ctx->exprs, &ctx->reg[ctx->ra_reg] );
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+   ppRegRule( ctx->exprs, &ctx->reg[ctx->reg_sp][ctx->ra_reg] );
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    VG_(printf)("FP=");
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-   ppRegRule( ctx->exprs, &ctx->reg[FP_REG] );
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+   ppRegRule( ctx->exprs, &ctx->reg[ctx->reg_sp][FP_REG] );
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    VG_(printf)("\n");
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 }
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@@ -2664,6 +2688,9 @@ static Int run_CF_instruction ( /*MOD*/U
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    Addr   printing_bias = ((Addr)ctx->initloc) - ((Addr)di->text_bias);
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    i++;
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+   if (ctx->reg_sp < 0 || ctx->reg_sp >= N_RR_STACK)
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+      return 0; /* bogus reg-rule stack pointer */
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+
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    if (hi2 == DW_CFA_advance_loc) {
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       delta = (UInt)lo6;
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       ctx->loc += delta;
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@@ -2680,12 +2707,13 @@ static Int run_CF_instruction ( /*MOD*/U
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       reg = (Int)lo6;
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       if (reg < 0 || reg >= N_CFI_REGS) 
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          return 0; /* fail */
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-      ctx->reg[reg].tag = RR_CFAOff;
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-      ctx->reg[reg].arg = off * ctx->data_a_f;
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+      ctx->reg[ctx->reg_sp][reg].tag = RR_CFAOff;
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+      ctx->reg[ctx->reg_sp][reg].arg = off * ctx->data_a_f;
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       if (di->ddump_frames)
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          VG_(printf)("  DW_CFA_offset: r%d at cfa%s%d\n",
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-                     (Int)reg, ctx->reg[reg].arg < 0 ? "" : "+", 
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-                     (Int)ctx->reg[reg].arg );
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+                     (Int)reg,
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+                     ctx->reg[ctx->reg_sp][reg].arg < 0 ? "" : "+", 
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+                     (Int)ctx->reg[ctx->reg_sp][reg].arg );
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       return i;
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    }
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@@ -2695,7 +2723,7 @@ static Int run_CF_instruction ( /*MOD*/U
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          return 0; /* fail */
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       if (restore_ctx == NULL)
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          return 0; /* fail */
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-      ctx->reg[reg] = restore_ctx->reg[reg];
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+      ctx->reg[ctx->reg_sp][reg] = restore_ctx->reg[ctx->reg_sp][reg];
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       if (di->ddump_frames)
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          VG_(printf)("  DW_CFA_restore: r%d\n", (Int)reg);
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       return i;
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@@ -2781,8 +2809,8 @@ static Int run_CF_instruction ( /*MOD*/U
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             return 0; /* fail */
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          if (reg2 < 0 || reg2 >= N_CFI_REGS) 
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_Reg;
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-         ctx->reg[reg].arg = reg2;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_Reg;
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+         ctx->reg[ctx->reg_sp][reg].arg = reg2;
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          if (di->ddump_frames)
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             VG_(printf)("  DW_CFA_register: r%d in r%d\n", 
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                         (Int)reg, (Int)reg2);
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@@ -2795,8 +2823,8 @@ static Int run_CF_instruction ( /*MOD*/U
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          i += nleb;
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          if (reg < 0 || reg >= N_CFI_REGS)
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_CFAOff;
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-         ctx->reg[reg].arg = off * ctx->data_a_f;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_CFAOff;
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+         ctx->reg[ctx->reg_sp][reg].arg = off * ctx->data_a_f;
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          if (di->ddump_frames)
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             VG_(printf)("  rci:DW_CFA_offset_extended\n");
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          break;
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@@ -2808,12 +2836,13 @@ static Int run_CF_instruction ( /*MOD*/U
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          i += nleb;
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          if (reg < 0 || reg >= N_CFI_REGS) 
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_CFAOff;
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-         ctx->reg[reg].arg = off * ctx->data_a_f;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_CFAOff;
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+         ctx->reg[ctx->reg_sp][reg].arg = off * ctx->data_a_f;
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          if (di->ddump_frames)
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             VG_(printf)("  DW_CFA_offset_extended_sf: r%d at cfa%s%d\n", 
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-                        reg, ctx->reg[reg].arg < 0 ? "" : "+", 
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-                        (Int)ctx->reg[reg].arg);
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+                        reg,
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+                        ctx->reg[ctx->reg_sp][reg].arg < 0 ? "" : "+", 
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+                        (Int)ctx->reg[ctx->reg_sp][reg].arg);
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          break;
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       case DW_CFA_GNU_negative_offset_extended:
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@@ -2823,8 +2852,8 @@ static Int run_CF_instruction ( /*MOD*/U
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          i += nleb;
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          if (reg < 0 || reg >= N_CFI_REGS)
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_CFAOff;
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-         ctx->reg[reg].arg = (-off) * ctx->data_a_f;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_CFAOff;
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+         ctx->reg[ctx->reg_sp][reg].arg = (-off) * ctx->data_a_f;
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          if (di->ddump_frames)
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             VG_(printf)("  rci:DW_CFA_GNU_negative_offset_extended\n");
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          break;
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@@ -2836,7 +2865,7 @@ static Int run_CF_instruction ( /*MOD*/U
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             return 0; /* fail */
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 	 if (restore_ctx == NULL)
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 	    return 0; /* fail */
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-	 ctx->reg[reg] = restore_ctx->reg[reg];
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+	 ctx->reg[ctx->reg_sp][reg] = restore_ctx->reg[ctx->reg_sp][reg];
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          if (di->ddump_frames)
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             VG_(printf)("  rci:DW_CFA_restore_extended\n");
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          break;
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@@ -2848,8 +2877,8 @@ static Int run_CF_instruction ( /*MOD*/U
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          i += nleb;
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          if (reg < 0 || reg >= N_CFI_REGS)
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_CFAValOff;
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-         ctx->reg[reg].arg = off * ctx->data_a_f;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_CFAValOff;
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+         ctx->reg[ctx->reg_sp][reg].arg = off * ctx->data_a_f;
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          if (di->ddump_frames)
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             VG_(printf)("  rci:DW_CFA_val_offset\n");
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          break;
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@@ -2861,8 +2890,8 @@ static Int run_CF_instruction ( /*MOD*/U
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          i += nleb;
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          if (reg < 0 || reg >= N_CFI_REGS)
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_CFAValOff;
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-         ctx->reg[reg].arg = off * ctx->data_a_f;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_CFAValOff;
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+         ctx->reg[ctx->reg_sp][reg].arg = off * ctx->data_a_f;
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          if (di->ddump_frames)
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             VG_(printf)("  rci:DW_CFA_val_offset_sf\n");
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          break;
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@@ -2907,8 +2936,8 @@ static Int run_CF_instruction ( /*MOD*/U
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          i += nleb;
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          if (reg < 0 || reg >= N_CFI_REGS) 
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_Undef;
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-         ctx->reg[reg].arg = 0;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_Undef;
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+         ctx->reg[ctx->reg_sp][reg].arg = 0;
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          if (di->ddump_frames)
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             VG_(printf)("  rci:DW_CFA_undefined\n");
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          break;
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@@ -2952,8 +2981,8 @@ static Int run_CF_instruction ( /*MOD*/U
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             return 0; /* fail */
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          /* Add an extra dereference */
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          j = ML_(CfiExpr_Deref)( ctx->exprs, j );
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-         ctx->reg[reg].tag = RR_ValExpr;
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-         ctx->reg[reg].arg = j;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_ValExpr;
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+         ctx->reg[ctx->reg_sp][reg].arg = j;
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          break;
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       case DW_CFA_val_expression:
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@@ -2981,8 +3010,8 @@ static Int run_CF_instruction ( /*MOD*/U
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          }
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          if (j == -1)
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             return 0; /* fail */
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-         ctx->reg[reg].tag = RR_ValExpr;
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-         ctx->reg[reg].arg = j;
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+         ctx->reg[ctx->reg_sp][reg].tag = RR_ValExpr;
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+         ctx->reg[ctx->reg_sp][reg].arg = j;
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          break;
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       case DW_CFA_def_cfa_expression:
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@@ -3008,7 +3037,39 @@ static Int run_CF_instruction ( /*MOD*/U
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          /* Ignored.  This appears to be sparc-specific; quite why it
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             turns up in SuSE-supplied x86 .so's beats me. */
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          if (di->ddump_frames)
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-            VG_(printf)("DW_CFA_GNU_window_save\n");
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+            VG_(printf)("  DW_CFA_GNU_window_save\n");
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+         break;
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+
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+      case DW_CFA_remember_state:
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+         if (di->ddump_frames)
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+            VG_(printf)("  DW_CFA_remember_state\n");
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+         /* we just checked this at entry, so: */
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+         vg_assert(ctx->reg_sp >= 0 && ctx->reg_sp < N_RR_STACK);
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+         ctx->reg_sp++;
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+         if (ctx->reg_sp == N_RR_STACK) {
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+            /* stack overflow.  We're hosed. */
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+            VG_(message)(Vg_DebugMsg, "DWARF2 CFI reader: N_RR_STACK is "
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+                                      "too low; increase and recompile.");
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+            i = 0; /* indicate failure */
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+         } else {
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+            VG_(memcpy)(/*dst*/&ctx->reg[ctx->reg_sp],
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+                        /*src*/&ctx->reg[ctx->reg_sp - 1],
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+                        sizeof(ctx->reg[ctx->reg_sp]) );
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+         }
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+         break;
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+
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+      case DW_CFA_restore_state:
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+         if (di->ddump_frames)
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+            VG_(printf)("  DW_CFA_restore_state\n");
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+         /* we just checked this at entry, so: */
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+         vg_assert(ctx->reg_sp >= 0 && ctx->reg_sp < N_RR_STACK);
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+         if (ctx->reg_sp == 0) {
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+            /* stack overflow.  Give up. */
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+            i = 0; /* indicate failure */
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+         } else {
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+            /* simply fall back to previous entry */
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+            ctx->reg_sp--;
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+         }
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          break;
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       default: