mips-protos.h (mips_linked_macc_p): Declare.

	* config/mips/mips-protos.h (mips_linked_macc_p): Declare.
	* config/mips/mips.h (TUNE_MACC_CHAINS): New macro.
	* config/mips/mips.c (TARGET_SCHED_REORDER): Define.
	(TARGET_SCHED_VARIABLE_ISSUE): Define.
	(mips_adjust_cost): Move later in file, next to other sched hooks.
	(mips_macc_chains_last_hilo): New variable.
	(mips_linked_madd_p, mips_macc_chains_record, mips_macc_chains_reorder)
	(mips_promote_ready, mips_sched_reorder, mips_variable_issue): New.
	* config/mips/mips.md (may_clobber_hilo): New attribute.

From-SVN: r81157

5 files changed, 197 insertions, 15 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8c70524..b5f9080 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,15 @@
+2004-04-25  Richard Sandiford  <rsandifo@redhat.com>
+
+	* config/mips/mips-protos.h (mips_linked_macc_p): Declare.
+	* config/mips/mips.h (TUNE_MACC_CHAINS): New macro.
+	* config/mips/mips.c (TARGET_SCHED_REORDER): Define.
+	(TARGET_SCHED_VARIABLE_ISSUE): Define.
+	(mips_adjust_cost): Move later in file, next to other sched hooks.
+	(mips_macc_chains_last_hilo): New variable.
+	(mips_linked_madd_p, mips_macc_chains_record, mips_macc_chains_reorder)
+	(mips_promote_ready, mips_sched_reorder, mips_variable_issue): New.
+	* config/mips/mips.md (may_clobber_hilo): New attribute.
+
 2004-04-24  Roger Sayle  <roger@eyesopen.com>
 	    Bruce Korb  <bkorb@gnu.org>
 
diff --git a/gcc/config/mips/mips-protos.h b/gcc/config/mips/mips-protos.h
index 761cf47..f3b7bdbed 100644
--- a/gcc/config/mips/mips-protos.h
+++ b/gcc/config/mips/mips-protos.h
@@ -201,6 +201,7 @@ extern const char *mips_output_conditional_branch (rtx, rtx *, int, int,
 						   int, int);
 extern const char *mips_output_division (const char *, rtx *);
 extern unsigned int mips_hard_regno_nregs (int, enum machine_mode);
+extern bool mips_linked_madd_p (rtx, rtx);
 extern const char *mips_emit_prefetch (rtx *);
 
 extern void irix_asm_output_align (FILE *, unsigned);
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 9720c7d..bbb664e 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -226,9 +226,14 @@ static bool mips_strict_matching_cpu_name_p (const char *, const char *);
 static bool mips_matching_cpu_name_p (const char *, const char *);
 static const struct mips_cpu_info *mips_parse_cpu (const char *, const char *);
 static const struct mips_cpu_info *mips_cpu_info_from_isa (int);
-static int mips_adjust_cost (rtx, rtx, rtx, int);
 static bool mips_return_in_memory (tree, tree);
 static bool mips_strict_argument_naming (CUMULATIVE_ARGS *);
+static void mips_macc_chains_record (rtx);
+static void mips_macc_chains_reorder (rtx *, int);
+static void mips_promote_ready (rtx *, int, int);
+static int mips_sched_reorder (FILE *, int, rtx *, int *, int);
+static int mips_variable_issue (FILE *, int, rtx, int);
+static int mips_adjust_cost (rtx, rtx, rtx, int);
 static int mips_issue_rate (void);
 static int mips_use_dfa_pipeline_interface (void);
 static int mips_multipass_dfa_lookahead (void);
@@ -670,6 +675,10 @@ const struct mips_cpu_info mips_cpu_info_table[] = {
 #undef TARGET_ASM_SELECT_RTX_SECTION
 #define TARGET_ASM_SELECT_RTX_SECTION mips_select_rtx_section
 
+#undef TARGET_SCHED_REORDER
+#define TARGET_SCHED_REORDER mips_sched_reorder
+#undef TARGET_SCHED_VARIABLE_ISSUE
+#define TARGET_SCHED_VARIABLE_ISSUE mips_variable_issue
 #undef TARGET_SCHED_ADJUST_COST
 #define TARGET_SCHED_ADJUST_COST mips_adjust_cost
 #undef TARGET_SCHED_ISSUE_RATE
@@ -9152,20 +9161,6 @@ mips_cpu_info_from_isa (int isa)
   return 0;
 }
 
-/* Adjust the cost of INSN based on the relationship between INSN that
-   is dependent on DEP_INSN through the dependence LINK.  The default
-   is to make no adjustment to COST.
-
-   On the MIPS, ignore the cost of anti- and output-dependencies.  */
-static int
-mips_adjust_cost (rtx insn ATTRIBUTE_UNUSED, rtx link,
-		  rtx dep ATTRIBUTE_UNUSED, int cost)
-{
-  if (REG_NOTE_KIND (link) != 0)
-    return 0;	/* Anti or output dependence.  */
-  return cost;
-}
-
 /* Implement HARD_REGNO_NREGS.  The size of FP registers are controlled
    by UNITS_PER_FPREG.  All other registers are word sized.  */
 
@@ -9200,6 +9195,140 @@ mips_strict_argument_naming (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
   return !TARGET_OLDABI;
 }
 
+/* Return true if INSN is a multiply-add or multiply-subtract
+   instruction and PREV assigns to the accumulator operand.  */
+
+bool
+mips_linked_madd_p (rtx prev, rtx insn)
+{
+  rtx x;
+
+  x = single_set (insn);
+  if (x == 0)
+    return false;
+
+  x = SET_SRC (x);
+
+  if (GET_CODE (x) == PLUS
+      && GET_CODE (XEXP (x, 0)) == MULT
+      && reg_set_p (XEXP (x, 1), prev))
+    return true;
+
+  if (GET_CODE (x) == MINUS
+      && GET_CODE (XEXP (x, 1)) == MULT
+      && reg_set_p (XEXP (x, 0), prev))
+    return true;
+
+  return false;
+}
+
+/* Used by TUNE_MACC_CHAINS to record the last scheduled instruction
+   that may clobber hi or lo.  */
+
+static rtx mips_macc_chains_last_hilo;
+
+/* A TUNE_MACC_CHAINS helper function.  Record that instruction INSN has
+   been scheduled, updating mips_macc_chains_last_hilo appropriately.  */
+
+static void
+mips_macc_chains_record (rtx insn)
+{
+  if (get_attr_may_clobber_hilo (insn))
+    mips_macc_chains_last_hilo = insn;
+}
+
+/* A TUNE_MACC_CHAINS helper function.  Search ready queue READY, which
+   has NREADY elements, looking for a multiply-add or multiply-subtract
+   instruction that is cumulative with mips_macc_chains_last_hilo.
+   If there is one, promote it ahead of anything else that might
+   clobber hi or lo.  */
+
+static void
+mips_macc_chains_reorder (rtx *ready, int nready)
+{
+  int i, j;
+
+  if (mips_macc_chains_last_hilo != 0)
+    for (i = nready - 1; i >= 0; i--)
+      if (mips_linked_madd_p (mips_macc_chains_last_hilo, ready[i]))
+	{
+	  for (j = nready - 1; j > i; j--)
+	    if (recog_memoized (ready[j]) >= 0
+		&& get_attr_may_clobber_hilo (ready[j]))
+	      {
+		mips_promote_ready (ready, i, j);
+		break;
+	      }
+	  break;
+	}
+}
+
+/* Remove the instruction at index LOWER from ready queue READY and
+   reinsert it in front of the instruction at index HIGHER.  LOWER must
+   be <= HIGHER.  */
+
+static void
+mips_promote_ready (rtx *ready, int lower, int higher)
+{
+  rtx new_head;
+  int i;
+
+  new_head = ready[lower];
+  for (i = lower; i < higher; i++)
+    ready[i] = ready[i + 1];
+  ready[i] = new_head;
+}
+
+/* Implement TARGET_SCHED_REORDER.  */
+
+static int
+mips_sched_reorder (FILE *file ATTRIBUTE_UNUSED, int verbose ATTRIBUTE_UNUSED,
+		    rtx *ready, int *nreadyp, int cycle)
+{
+  if (!reload_completed && TUNE_MACC_CHAINS)
+    {
+      if (cycle == 0)
+	mips_macc_chains_last_hilo = 0;
+      if (*nreadyp > 0)
+	mips_macc_chains_reorder (ready, *nreadyp);
+    }
+  return mips_issue_rate ();
+}
+
+/* Implement TARGET_SCHED_VARIABLE_ISSUE.  */
+
+static int
+mips_variable_issue (FILE *file ATTRIBUTE_UNUSED, int verbose ATTRIBUTE_UNUSED,
+		     rtx insn, int more)
+{
+  switch (GET_CODE (PATTERN (insn)))
+    {
+    case USE:
+    case CLOBBER:
+      /* Don't count USEs and CLOBBERs against the issue rate.  */
+      break;
+
+    default:
+      more--;
+      if (!reload_completed && TUNE_MACC_CHAINS)
+	mips_macc_chains_record (insn);
+      break;
+    }
+  return more;
+}
+
+/* Implement TARGET_SCHED_ADJUST_COST.  We assume that anti and output
+   dependencies have no cost.  */
+
+static int
+mips_adjust_cost (rtx insn ATTRIBUTE_UNUSED, rtx link,
+		  rtx dep ATTRIBUTE_UNUSED, int cost)
+{
+  if (REG_NOTE_KIND (link) != 0)
+    return 0;
+  return cost;
+}
+
 /* Return the number of instructions that can be issued per cycle.  */
 
 static int
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 73fbe71..e678ba9 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -340,6 +340,39 @@ extern const struct mips_cpu_info *mips_tune_info;
 #define TUNE_MIPS9000               (mips_tune == PROCESSOR_R9000)
 #define TUNE_SB1                    (mips_tune == PROCESSOR_SB1)
 
+/* True if the pre-reload scheduler should try to create chains of
+   multiply-add or multiply-subtract instructions.  For example,
+   suppose we have:
+
+	t1 = a * b
+	t2 = t1 + c * d
+	t3 = c * d
+	t4 = t3 - c * d
+
+   t1 will have a higher priority and t2 and t3 will have a higher
+   priority than t4.  However, before reload, there is no dependence
+   between t1 and t3, and they can often have similar priorities.
+   The scheduler will then tend to prefer:
+
+	t1 = a * b
+	t3 = e * f
+	t2 = t1 + c * d
+	t4 = t3 - g * h
+
+   which stops us from making full use of macc/madd-style instructions.
+   This sort of situation occurs frequently in Fourier transforms and
+   in unrolled loops.
+
+   To counter this, the TUNE_MACC_CHAINS code will reorder the ready
+   queue so that chained multiply-add and multiply-subtract instructions
+   appear ahead of any other instruction that is likely to clobber lo.
+   In the example above, if t2 and t3 become ready at the same time,
+   the code ensures that t2 is scheduled first.
+
+   Multiply-accumulate instructions are a bigger win for some targets
+   than others, so this macro is defined on an opt-in basis.  */
+#define TUNE_MACC_CHAINS	    TUNE_MIPS5500
+
 #define TARGET_OLDABI		    (mips_abi == ABI_32 || mips_abi == ABI_O64)
 #define TARGET_NEWABI		    (mips_abi == ABI_N32 || mips_abi == ABI_64)
 
diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
index 7f36d63..d5071dd 100644
--- a/gcc/config/mips/mips.md
+++ b/gcc/config/mips/mips.md
@@ -277,6 +277,13 @@
 		 (const_string "yes")
 		 (const_string "no"))))
 
+;; True if an instruction might assign to hi or lo when reloaded.
+;; This is used by the TUNE_MACC_CHAINS code.
+(define_attr "may_clobber_hilo" "no,yes"
+  (if_then_else (eq_attr "type" "imul,imadd,idiv,mthilo")
+		(const_string "yes")
+		(const_string "no")))
+
 ;; Describe a user's asm statement.
 (define_asm_attributes
   [(set_attr "type" "multi")])