[SFrame-V3] gas: sframe: output new FDE type SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME

This patch updates the routines for emission of the new FDE type
SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME in the SFrame output section.  The
support for generating the flex-topmost-frame FDEs themselves is added
in a subsequent commit.

For flex topmost FDE type, output_sframe_row_entry_offsets () emits two
offsets for RA tracking, irrespective of the ABI/arch, i.e.,
irrespecitve of whether RA-tracking is enabled.  This is because, for
flexible topmost frames, RA is allowed "non-standard" recovery rules,
e.g., RA = REG or RA = *(REG+offset).  In a follow-up patch, when
handling for .cfi_register RA, REG is added, emission code will be
patched up accodingly.

gas/
	* gen-sframe.c (get_fre_num_offsets): Get number of offsets for
	SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME fde type as well (new
	argument).
	(output_sframe_row_entry_offsets): Output the SFrame FREs for
	two different cases (fde type SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME
	or the default).
	(output_sframe_row_entry): Update caller.
	(output_sframe_funcdesc): Emit func type in func_info2 field.
	(sframe_xlate_ctx_init): Initialize flex_topmost_p in
	translation context object.
	(sframe_xlate_ctx_finalize): Likewise.
	(sframe_row_entry_initialize): Copy over new data members too.
	* gen-sframe.h (struct sframe_row_entry): Add tracking for CFA
	dereferencing, frame pointer dereferencing.
	(struct sframe_func_entry): Add tracking for flexible topmost
	frame.
	(struct sframe_xlate_ctx): Likewise.

diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index e2c3d1fafd8a037848e95862b4f9a49a395fc697..073a8374a4fe0dcecdf794e2f0115db368ef07d3 100644 (file)
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -380,19 +380,31 @@ get_fre_base_reg_id (const struct sframe_row_entry *sframe_fre)
 /* Get number of offsets necessary for the SFrame Frame Row Entry.  */
 
 static unsigned int
-get_fre_num_offsets (const struct sframe_row_entry *sframe_fre)
+get_fre_num_offsets (const struct sframe_row_entry *sframe_fre,
+                    bool flex_topmost_p)
 {
-  /* Atleast 1 must always be present (to recover CFA).  */
-  unsigned int fre_num_offsets = 1;
+  /* For SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME FDE type, each entity (CFA, FP, RA)
+     may carry up to two offsets.  */
+  unsigned int count = flex_topmost_p ? 2 : 1;
 
-  if (sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
-    fre_num_offsets++;
-  if (sframe_ra_tracking_p ()
-      && (sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK
-         /* For s390x account padding RA offset, if FP without RA saved.  */
-         || (sframe_get_abi_arch () == SFRAME_ABI_S390X_ENDIAN_BIG
-             && sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)))
+  /* CFA offset (or offsets when flex_topmost_p) must always be present.  */
+  unsigned int fre_num_offsets = count;
+
+  /* For flexible topmost frames encoding, there will be two offsets for RA
+     (irrespective of whether RA tracking is enabled or not).  */
+  if (flex_topmost_p)
+    fre_num_offsets += count;
+  else if (sframe_ra_tracking_p ()
+          && (sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK
+              /* For s390x account padding RA offset, if FP without RA
+                 saved.  */
+              || (sframe_get_abi_arch () == SFRAME_ABI_S390X_ENDIAN_BIG
+                  && sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)))
     fre_num_offsets++;
+
+  if (sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
+    fre_num_offsets += count;
+
   return fre_num_offsets;
 }
 
@@ -587,39 +599,84 @@ sframe_fde_free (struct sframe_func_entry *sframe_fde)
    size FRE_OFFSET_SIZE.  Write out the offsets in order - CFA, RA, FP.  */
 
 static unsigned int
-output_sframe_row_entry_offsets (const struct sframe_func_entry *sframe_fde ATTRIBUTE_UNUSED,
+output_sframe_row_entry_offsets (const struct sframe_func_entry *sframe_fde,
                                 const struct sframe_row_entry *sframe_fre,
                                 unsigned int fre_offset_size)
-
 {
   unsigned int fre_write_offsets = 0;
 
   unsigned int idx = sframe_fre_offset_func_map_index (fre_offset_size);
   gas_assert (idx < SFRAME_FRE_OFFSET_FUNC_MAP_INDEX_MAX);
 
-  /* Write out the offsets in order - cfa, fp, ra.  */
-  fre_offset_func_map[idx].out_func (sframe_fre->cfa_offset);
-  fre_write_offsets++;
-
-  if (sframe_ra_tracking_p ())
+  if (sframe_fde->fde_flex_topmost_p)
     {
-      if (sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK)
+      /* SFrame FDE of type SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME.  */
+      /* Output CFA related FRE offsets.  */
+      uint8_t reg_data
+       = SFRAME_V3_FLEX_FDE_REG_ENCODE (sframe_fre->cfa_base_reg,
+                                        sframe_fre->cfa_deref_p,
+                                        1 /* reg_p.  */);
+      offsetT offset_data = sframe_fre->cfa_offset;
+      fre_offset_func_map[idx].out_func (reg_data);
+      fre_offset_func_map[idx].out_func (offset_data);
+      fre_write_offsets += 2;
+
+      /* Not expected.  Flexible Topmost Frame FDEs are not implemented ATM
+        for ABIs other than SFRAME_ABI_AMD64_ENDIAN_LITTLE.  If need arises,
+        the implementation may be added later as it will be backwards
+        compatible to add a new FDE type for those ABIs.  */
+      if (sframe_ra_tracking_p ())
+       gas_assert (false);
+
+      /* RA tracking enabled or not, emit two offsets for RA.
+        Aside, emitting SFRAME_FRE_RA_OFFSET_INVALID is equivalent to emitting
+        SFRAME_V3_FLEX_FDE_REG_ENCODE (0, 0, 0).
+        FIXME - This may change later when we implement handling .cfi_register
+        RA, reg.  Emit two 0 offsets for now.  */
+      fre_offset_func_map[idx].out_func (SFRAME_FRE_RA_OFFSET_INVALID);
+      /* FIXME Offset 0 for now.  */
+      fre_offset_func_map[idx].out_func (0);
+      fre_write_offsets += 2;
+
+      if (sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
        {
-         fre_offset_func_map[idx].out_func (sframe_fre->ra_offset);
-         fre_write_offsets++;
-       }
-      /* For s390x write padding RA offset, if FP without RA saved.  */
-      else if (sframe_get_abi_arch () == SFRAME_ABI_S390X_ENDIAN_BIG
-              && sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
-       {
-         fre_offset_func_map[idx].out_func (SFRAME_FRE_RA_OFFSET_INVALID);
-         fre_write_offsets++;
+         /* Output FP related FRE offsets.  */
+         reg_data = SFRAME_V3_FLEX_FDE_REG_ENCODE (sframe_fre->fp_reg,
+                                                   sframe_fre->fp_deref_p,
+                                                   1 /* reg_p.  */);
+         offset_data = sframe_fre->fp_offset;
+         fre_offset_func_map[idx].out_func (reg_data);
+         fre_offset_func_map[idx].out_func (offset_data);
+         fre_write_offsets += 2;
        }
     }
-  if (sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
+  else
     {
-      fre_offset_func_map[idx].out_func (sframe_fre->fp_offset);
+      /* SFrame FDE of type SFRAME_FDE_TYPE_PCINC.  */
+      /* Output CFA related FRE offsets.  */
+      fre_offset_func_map[idx].out_func (sframe_fre->cfa_offset);
       fre_write_offsets++;
+
+      if (sframe_ra_tracking_p ())
+       {
+         if (sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK)
+           {
+             fre_offset_func_map[idx].out_func (sframe_fre->ra_offset);
+             fre_write_offsets++;
+           }
+         /* For s390x write padding RA offset, if FP without RA saved.  */
+         else if (sframe_get_abi_arch () == SFRAME_ABI_S390X_ENDIAN_BIG
+                  && sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
+           {
+             fre_offset_func_map[idx].out_func (SFRAME_FRE_RA_OFFSET_INVALID);
+             fre_write_offsets++;
+           }
+       }
+      if (sframe_fre->fp_loc == SFRAME_FRE_ELEM_LOC_STACK)
+       {
+         fre_offset_func_map[idx].out_func (sframe_fre->fp_offset);
+         fre_write_offsets++;
+       }
     }
 
   return fre_write_offsets;
@@ -676,7 +733,8 @@ output_sframe_row_entry (const struct sframe_func_entry *sframe_fde,
   else
     {
       fre_base_reg = get_fre_base_reg_id (sframe_fre);
-      fre_num_offsets = get_fre_num_offsets (sframe_fre);
+      fre_num_offsets = get_fre_num_offsets (sframe_fre,
+                                            sframe_fde->fde_flex_topmost_p);
       fre_offset_size = sframe_get_fre_offset_size (sframe_fre);
       fre_mangled_ra_p = sframe_fre->mangled_ra_p;
     }
@@ -763,7 +821,19 @@ output_sframe_funcdesc (symbolS *start_of_fre_section,
     }
   else
     out_one (func_info);
-  out_one (0);
+
+  if (sframe_fde->fde_flex_topmost_p)
+    {
+      uint8_t finfo2 = 0;
+      if (sframe_fde->fde_flex_topmost_p)
+       {
+         uint8_t fde_type = SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME;
+         finfo2 = SFRAME_V3_FUNC_INFO2_SET_FDE_TYPE (finfo2, fde_type);
+       }
+    }
+  else
+    out_one (0);
+
   out_one (0);
 }
 
@@ -947,6 +1017,7 @@ static void
 sframe_xlate_ctx_init (struct sframe_xlate_ctx *xlate_ctx)
 {
   xlate_ctx->dw_fde = NULL;
+  xlate_ctx->flex_topmost_p = false;
   xlate_ctx->first_fre = NULL;
   xlate_ctx->last_fre = NULL;
   xlate_ctx->cur_fre = NULL;
@@ -971,6 +1042,7 @@ sframe_xlate_ctx_finalize (struct sframe_xlate_ctx *xlate_ctx,
                           struct sframe_func_entry *sframe_fde)
 {
   sframe_fde->dw_fde = xlate_ctx->dw_fde;
+  sframe_fde->fde_flex_topmost_p = xlate_ctx->flex_topmost_p;
   sframe_fde->sframe_fres = xlate_ctx->first_fre;
   sframe_fde->num_fres = xlate_ctx->num_xlate_fres;
 }
@@ -1023,8 +1095,11 @@ sframe_row_entry_initialize (struct sframe_row_entry *cur_fre,
   gas_assert (prev_fre);
   cur_fre->cfa_base_reg = prev_fre->cfa_base_reg;
   cur_fre->cfa_offset = prev_fre->cfa_offset;
+  cur_fre->cfa_deref_p = prev_fre->cfa_deref_p;
   cur_fre->fp_loc = prev_fre->fp_loc;
+  cur_fre->fp_reg = prev_fre->fp_reg;
   cur_fre->fp_offset = prev_fre->fp_offset;
+  cur_fre->fp_deref_p = prev_fre->fp_deref_p;
   cur_fre->ra_loc = prev_fre->ra_loc;
   cur_fre->ra_offset = prev_fre->ra_offset;
   /* Treat RA mangling as a sticky bit.  It retains its value until another

diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
index c4d621b01732aab3224d3fac199237a93ba1cad2..4921e796a10b6b91db811ee133a3866c40c5e5cf 100644 (file)
--- a/gas/gen-sframe.h
+++ b/gas/gen-sframe.h
@@ -73,12 +73,18 @@ struct sframe_row_entry
   unsigned int cfa_base_reg;
   /* Offset from the CFA base register for recovering CFA.  */
   offsetT cfa_offset;
+  /* Whether CFA recovery needs dereferencing.  This is tracked for
+     SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME SFrame FDE type.  */
+  bool cfa_deref_p;
 
   /* Track FP location.  Specify whether it is in register or memory.  */
   unsigned int fp_reg;
   unsigned int fp_loc;
   /* If the FP is stashed on stack, note the offset.  */
   offsetT fp_offset;
+  /* Whether FP recovery needs dereferencing.  This is tracked for
+     SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME SFrame FDE type.  */
+  bool fp_deref_p;
 
   /* Track RA location.  Specify whether it is in register or memory.  */
   unsigned int ra_loc;
@@ -97,6 +103,9 @@ struct sframe_func_entry
      like the start_address and the segment is made available via this
      member.  */
   const struct fde_entry *dw_fde;
+  /* Whether the current FDE will use SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME
+     representation.  */
+  bool fde_flex_topmost_p;
 
   /* Reference to the first FRE for this function.  */
   struct sframe_row_entry *sframe_fres;
@@ -127,6 +136,10 @@ struct sframe_xlate_ctx
   /* Remember FRE for an eventual restore.  */
   struct sframe_row_entry *remember_fre;
 
+  /* Whether the current FRE requires a more flexible topmost frame, hence
+     needing SFRAME_FDE_TYPE_FLEX_TOPMOST_FRAME SFrame FDE type.  */
+  bool flex_topmost_p;
+
   unsigned num_xlate_fres;
 };