* mn10300-tdep.c (mn10300_analyze_prologue): Implement backtrack

	out of pattern match by saving relevant state.  Fix stack size
	adjustment bug.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index dfe5cba..de59ea5 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2006-02-28  Kevin Buettner  <kevinb@redhat.com>
+
+       * mn10300-tdep.c (mn10300_analyze_prologue):  Implement backtrack
+       out of pattern match by saving relevant state.  Fix stack size
+       adjustment bug.
+
 2006-02-28  Alexandre Oliva  <aoliva@redhat.com>
 
        * solib-svr4.h (struct link_map_offsets): Add l_ld_offset and

diff --git a/gdb/mn10300-tdep.c b/gdb/mn10300-tdep.c
index 81152ad..47844d1 100644 (file)
--- a/gdb/mn10300-tdep.c
+++ b/gdb/mn10300-tdep.c
@@ -620,6 +620,17 @@ mn10300_analyze_prologue (struct frame_info *fi,
        [mov sp,a3]        [mov sp,a3]
        [add -SIZE2,sp]    [add -SIZE2,sp]                                 */
 
+      /* Remember the address at which we started in the event that we
+        don't ultimately find an fmov instruction.  Once we're certain
+        that we matched one of the above patterns, we'll set
+        ``restore_addr'' to the appropriate value.  Note: At one time
+        in the past, this code attempted to not adjust ``addr'' until
+        there was a fair degree of certainty that the pattern would be
+        matched.  However, that code did not wait until an fmov instruction
+        was actually encountered.  As a consequence, ``addr'' would
+        sometimes be advanced even when no fmov instructions were found.  */
+      CORE_ADDR restore_addr = addr;
+
       /* First, look for add -SIZE,sp (i.e. add imm8,sp  (0xf8feXX)
                                          or add imm16,sp (0xfafeXXXX)
                                          or add imm32,sp (0xfcfeXXXXXXXX)) */
@@ -651,10 +662,10 @@ mn10300_analyze_prologue (struct frame_info *fi,
                     This is a one byte instruction:  mov sp,aN = 0011 11XX
                     where XX is the register number.
 
-                    Skip this instruction by incrementing addr. (We're
-                    committed now.) The "fmov" instructions will have the
-                    form "fmov fs#,(aN+)" in this case, but that will not
-                    necessitate a change in the "fmov" parsing logic below. */
+                    Skip this instruction by incrementing addr.  The "fmov"
+                    instructions will have the form "fmov fs#,(aN+)" in this
+                    case, but that will not necessitate a change in the
+                    "fmov" parsing logic below. */
 
                  addr++;
 
@@ -698,6 +709,14 @@ mn10300_analyze_prologue (struct frame_info *fi,
                      if (buf[0] != 0xf9 && buf[0] != 0xfb)
                        break;
 
+                     /* An fmov instruction has just been seen.  We can
+                        now really commit to the pattern match.  Set the
+                        address to restore at the end of this speculative
+                        bit of code to the actually address that we've
+                        been incrementing (or not) throughout the
+                        speculation.  */
+                     restore_addr = addr;
+
                      /* Get the floating point register number from the 
                         2nd and 3rd bytes of the "fmov" instruction:
                         Machine Code: 0000 00X0 YYYY 0000 =>
@@ -719,6 +738,7 @@ mn10300_analyze_prologue (struct frame_info *fi,
                {
                  /* No "fmov" was found. Reread the two bytes at the original
                     "addr" to reset the state. */
+                 addr = restore_addr;
                  if (!safe_frame_unwind_memory (fi, addr, buf, 2))
                    goto finish_prologue;
                }
@@ -727,8 +747,16 @@ mn10300_analyze_prologue (struct frame_info *fi,
             instruction. Handle this below. */
        }
       /* else no "add -SIZE,sp" was found indicating no floating point
-        registers are saved in this prologue. Do not increment addr. Pretend
-        this bit of code never happened. */
+        registers are saved in this prologue.  */
+
+      /* In the pattern match code contained within this block, `restore_addr'
+        is set to the starting address at the very beginning and then
+        iteratively to the next address to start scanning at once the
+        pattern match has succeeded.  Thus `restore_addr' will contain
+        the address to rewind to if the pattern match failed.  If the
+        match succeeded, `restore_addr' and `addr' will already have the
+        same value.  */
+      addr = restore_addr;
     }
 
   /* Now see if we set up a frame pointer via "mov sp,a3" */
@@ -777,7 +805,7 @@ mn10300_analyze_prologue (struct frame_info *fi,
        goto finish_prologue;
 
       /* Note the size of the stack.  */
-      stack_extra_size += extract_signed_integer (buf, imm_size);
+      stack_extra_size -= extract_signed_integer (buf, imm_size);
 
       /* We just consumed 2 + imm_size bytes.  */
       addr += 2 + imm_size;