From b5aff26825abb88d44d71392f759c0a89e979285 Mon Sep 17 00:00:00 2001
From: Jim Kingdon <jkingdon@engr.sgi.com>
Date: Tue, 1 Mar 1994 00:15:07 +0000
Subject: [PATCH] 	* mips-tdep.c (mips_step_skips_delay),
 config/mips/tm-mips.h 	(STEP_SKIPS_DELAY): Added. 	* infrun.c (proceed)
 [STEP_SKIPS_DELAY]: Check for a breakpoint in 	the delay slot.

---
 gdb/ChangeLog             |  5 +++++
 gdb/config/mips/tm-mips.h |  4 ++++
 gdb/infrun.c              |  9 +++++++++
 gdb/mips-tdep.c           | 18 ++++++++++++++----
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d0c30b3124..c6e5b11c64 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 Mon Feb 28 12:40:46 1994  Jim Kingdon  (kingdon@deneb.cygnus.com)
 
+	* mips-tdep.c (mips_step_skips_delay), config/mips/tm-mips.h
+	(STEP_SKIPS_DELAY): Added.
+	* infrun.c (proceed) [STEP_SKIPS_DELAY]: Check for a breakpoint in
+	the delay slot.
+
 	* valprint.c (val_print_string): If errcode is set, always print
 	an error, regardless of force_ellipsis.  In the non-EIO case,
 	just print the error message rather than calling error().  Don't
diff --git a/gdb/config/mips/tm-mips.h b/gdb/config/mips/tm-mips.h
index a0d0c89047..11326bf145 100644
--- a/gdb/config/mips/tm-mips.h
+++ b/gdb/config/mips/tm-mips.h
@@ -46,6 +46,10 @@ extern int mips_fpu;
 #define SKIP_PROLOGUE(pc)	pc = mips_skip_prologue (pc, 0)
 extern CORE_ADDR mips_skip_prologue PARAMS ((CORE_ADDR addr, int lenient));
 
+/* Return non-zero if PC points to an instruction which will cause a step
+   to execute both the instruction at PC and an instruction at PC+4.  */
+#define STEP_SKIPS_DELAY(pc) (mips_step_skips_delay (pc))
+
 /* Immediately after a function call, return the saved pc.
    Can't always go through the frames for this because on some machines
    the new frame is not set up until the new function executes
diff --git a/gdb/infrun.c b/gdb/infrun.c
index ef9b82603a..146621c75b 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -280,6 +280,15 @@ proceed (addr, siggnal, step)
 
       if (breakpoint_here_p (read_pc ()))
 	oneproc = 1;
+
+#ifdef STEP_SKIPS_DELAY
+      /* Check breakpoint_here_p first, because breakpoint_here_p is fast
+	 (it just checks internal GDB data structures) and STEP_SKIPS_DELAY
+	 is slow (it needs to read memory from the target).  */
+      if (breakpoint_here_p (read_pc () + 4)
+	  && STEP_SKIPS_DELAY (read_pc ()))
+	oneproc = 1;
+#endif /* STEP_SKIPS_DELAY */
     }
   else
     write_pc (addr);
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index 9a5d6b92d4..faaeb6e192 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -32,9 +32,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #include "objfiles.h"
 #include "gdbtypes.h"
 
-#if 0
 #include "opcode/mips.h"
-#endif
 
 #define VM_MIN_ADDRESS (unsigned)0x400000
 
@@ -921,8 +919,9 @@ mips_frame_num_args(fip)
 	return -1;
 }
 
-#if 0
 /* Is this a branch with a delay slot?  */
+static int is_delayed PARAMS ((unsigned long));
+
 static int
 is_delayed (insn)
      unsigned long insn;
@@ -937,7 +936,18 @@ is_delayed (insn)
 				       | INSN_COND_BRANCH_DELAY
 				       | INSN_COND_BRANCH_LIKELY)));
 }
-#endif
+
+int
+mips_step_skips_delay (pc)
+     CORE_ADDR pc;
+{
+  char buf[4];
+
+  if (target_read_memory (pc, buf, 4) != 0)
+    /* If error reading memory, guess that it is not a delayed branch.  */
+    return 0;
+  return is_delayed (extract_unsigned_integer (buf, 4));
+}
 
 /* To skip prologues, I use this predicate.  Returns either PC itself
    if the code at PC does not look like a function prologue; otherwise