[PATCH] Some minor cleanups in dwarf2-frame.c

Mark Kettenis kettenis@chello.nl
Thu Nov 27 17:18:00 GMT 2003


I Committed this.  It reformats some comments, inproving punctation
and spelling in some cases.  The meaning of -ve wasn't immediately
clear to me so I spelled it out.  I added a few newlines where I had
trouble reading the code.

Mark


Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>
 
	* dwarf2-frame.c: Fix some comments and whitespace problems.

Index: dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.19
diff -u -p -r1.19 dwarf2-frame.c
--- dwarf2-frame.c 7 Nov 2003 20:36:15 -0000 1.19
+++ dwarf2-frame.c 27 Nov 2003 17:15:55 -0000
@@ -99,19 +99,18 @@ static struct dwarf2_fde *dwarf2_frame_f
 
 enum dwarf2_reg_rule
 {
-  /* Make certain that 0 maps onto the correct enum value - the
+  /* Make certain that 0 maps onto the correct enum value; the
      corresponding structure is being initialized using memset zero.
      This indicates that CFI didn't provide any information at all
-     about a register - leaving how to obtain it's value totally
+     about a register, leaving how to obtain it's value totally
      unspecified.  */
   REG_UNSPECIFIED = 0,
   /* The term "undefined" comes from the DWARF2 CFI spec which this
-     code is moddeling - it indicates that the register's value is
-     "undefined".  */
-  /* NOTE: cagney/2003-09-08: GCC uses the less formal term "unsaved"
-     - it's definition is a combination of REG_UNDEFINED and
-     REG_UNSPECIFIED - the failure to differentiate the two helps
-     explain a few problems with the CFI GCC outputs.  */
+     code is moddeling; it indicates that the register's value is
+     "undefined".  GCC uses the less formal term "unsaved".  Its
+     definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED.
+     The failure to differentiate the two helps explain a few problems
+     with the CFI generated by GCC.  */
   REG_UNDEFINED,
   REG_SAVED_OFFSET,
   REG_SAVED_REG,
@@ -500,18 +499,15 @@ dwarf2_frame_cache (struct frame_info *n
      to abort), the compiler might optimize away the instruction at
      NEXT_FRAME's return address.  As a result the return address will
      point at some random instruction, and the CFI for that
-     instruction is probably wortless to us.  GCC's unwinder solves
+     instruction is probably worthless to us.  GCC's unwinder solves
      this problem by substracting 1 from the return address to get an
      address in the middle of a presumed call instruction (or the
      instruction in the associated delay slot).  This should only be
      done for "normal" frames and not for resume-type frames (signal
-     handlers, sentinel frames, dummy frames).
-
-     frame_unwind_address_in_block does just this.
-
-     It's not clear how reliable the method is though - there is the
-     potential for the register state pre-call being different to that
-     on return.  */
+     handlers, sentinel frames, dummy frames).  The function
+     frame_unwind_address_in_block does just this.  It's not clear how
+     reliable the method is though; there is the potential for the
+     register state pre-call being different to that on return.  */
   fs->pc = frame_unwind_address_in_block (next_frame);
 
   /* Find the correct FDE.  */
@@ -555,6 +551,7 @@ dwarf2_frame_cache (struct frame_info *n
      unspecified.  */
   {
     int regnum;
+
     for (regnum = 0; regnum < num_regs; regnum++)
       cache->reg[regnum].how = REG_UNSPECIFIED;
   }
@@ -563,6 +560,7 @@ dwarf2_frame_cache (struct frame_info *n
      location information in the cache.  */
   {
     int column;		/* CFI speak for "register number".  */
+
     for (column = 0; column < fs->regs.num_regs; column++)
       {
 	int regnum;
@@ -573,9 +571,10 @@ dwarf2_frame_cache (struct frame_info *n
 	     RETADDR_COLUMN corresponds to a real register (and,
 	     worse, that isn't the PC_REGNUM)?  I'm guessing that the
 	     PC_REGNUM further down is trying to handle this.  That
-	     can't be right though - PC_REGNUM may not be valid (it
-	     can be -ve).  I think, instead when RETADDR_COLUM isn't a
-	     real register, it should map itself onto frame_pc_unwind.  */
+	     can't be right though; PC_REGNUM may not be valid (it can
+	     be negative).  I think, instead when RETADDR_COLUM isn't
+	     a real register, it should map itself onto
+	     frame_pc_unwind.  */
 	  continue;
 
 	/* Use the GDB register number as the destination index.  */
@@ -586,15 +585,15 @@ dwarf2_frame_cache (struct frame_info *n
 	  continue;
 
 	/* NOTE: cagney/2003-09-05: CFI should specify the disposition
-	   of all debug info registers.  If it doesn't complain (but
-	   not too loudly).  It turns out that GCC, assumes that an
+	   of all debug info registers.  If it doesn't, complain (but
+	   not too loudly).  It turns out that GCC assumes that an
 	   unspecified register implies "same value" when CFI (draft
 	   7) specifies nothing at all.  Such a register could equally
 	   be interpreted as "undefined".  Also note that this check
-	   isn't sufficient - it only checks that all registers in the
-	   range [0 .. max column] are specified - and won't detect
+	   isn't sufficient; it only checks that all registers in the
+	   range [0 .. max column] are specified, and won't detect
 	   problems when a debug info register falls outside of the
-	   table.  Need a way of iterating through all the valid
+	   table.  We need a way of iterating through all the valid
 	   DWARF2 register numbers.  */
 	if (fs->regs.reg[column].how == REG_UNSPECIFIED)
 	  complaint (&symfile_complaints,
@@ -606,14 +605,14 @@ dwarf2_frame_cache (struct frame_info *n
   }
 
   /* Store the location of the return addess.  If the return address
-     column (adjusted) is not the same as gdb's PC_REGNUM, then this
-     implies a copy from the ra column register.  */
+     column (adjusted) is not the same as GDB's PC_REGNUM, then this
+     implies a copy from the return address column register.  */
   if (fs->retaddr_column < fs->regs.num_regs
       && fs->regs.reg[fs->retaddr_column].how != REG_UNDEFINED)
     {
-      /* See comment above about a possibly -ve PC_REGNUM.  If this
-         assertion fails, it's a problem with this code and not the
-         architecture.  */
+      /* See comment above about a possibly negative PC_REGNUM.  If
+         this assertion fails, it's a problem with this code and not
+         the architecture.  */
       gdb_assert (PC_REGNUM >= 0);
       cache->reg[PC_REGNUM] = fs->regs.reg[fs->retaddr_column];
     }
@@ -622,9 +621,9 @@ dwarf2_frame_cache (struct frame_info *n
       int reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column);
       if (reg != PC_REGNUM)
 	{
-	  /* See comment above about PC_REGNUM being -ve.  If this
-	     assertion fails, it's a problem with this code and not
-	     the architecture.  */
+	  /* See comment above about PC_REGNUM being negative.  If
+	     this assertion fails, it's a problem with this code and
+	     not the architecture.  */
 	  gdb_assert (PC_REGNUM >= 0);
 	  cache->reg[PC_REGNUM].loc.reg = reg;
 	  cache->reg[PC_REGNUM].how = REG_SAVED_REG;
@@ -660,7 +659,7 @@ dwarf2_frame_prev_register (struct frame
     {
     case REG_UNDEFINED:
       /* If CFI explicitly specified that the value isn't defined,
-	 mark it as optimized away - the value isn't available.  */
+	 mark it as optimized away; the value isn't available.  */
       *optimizedp = 1;
       *lvalp = not_lval;
       *addrp = 0;
@@ -681,8 +680,8 @@ dwarf2_frame_prev_register (struct frame
 	  /* FIXME: cagney/2003-07-07: I don't understand this.  The
              CFI info should have provided unwind information for the
              SP register and then pointed ->cfa_reg at it, not the
-             reverse.  Assuming that SP_REGNUM is !-ve, there is a
-             very real posibility that CFA is an offset from some
+             reverse.  Assuming that SP_REGNUM isn't negative, there
+             is a very real posibility that CFA is an offset from some
              other register, having nothing to do with the unwound SP
              value.  */
 	  /* FIXME: cagney/2003-09-05: I think I understand.  GDB was
@@ -770,7 +769,7 @@ dwarf2_frame_prev_register (struct frame
              defines the rule which computes the CFA value; it may be
              either a register and a signed offset that are added
              together or a DWARF expression that is evaluated.  */
-	  /* NOTE: cagney/2003-09-05: Should issue a complain.
+	  /* NOTE: cagney/2003-09-05: Should issue a complaint.
              Unfortunately it turns out that DWARF2 CFI has a problem.
              Since CFI specifies the location at which a register was
              saved (not its value) it isn't possible to specify



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