Patchwork [02/14] rx: Remove rx_compare_redundant.

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Submitter Richard Henderson
Date Jan. 14, 2011, 4:08 p.m.
Message ID <1295021309-28608-3-git-send-email-rth@redhat.com>
Download mbox | patch
Permalink /patch/78935/
State New
Headers show

Comments

Richard Henderson - Jan. 14, 2011, 4:08 p.m.
From: Richard Henderson <rth@twiddle.net>

To be replaced by the generic compare_elim pass, but we need to disable
this before fiddling with the arrangement of the arithmetic instructions,
as required by the generic pass.
---
 gcc/config/rx/rx-protos.h |    1 -
 gcc/config/rx/rx.c        |  149 ---------------------------------------------
 gcc/config/rx/rx.md       |    7 +--
 3 files changed, 1 insertions(+), 156 deletions(-)

Patch

diff --git a/gcc/config/rx/rx-protos.h b/gcc/config/rx/rx-protos.h
index c5b7b6c..02e12ed 100644
--- a/gcc/config/rx/rx-protos.h
+++ b/gcc/config/rx/rx-protos.h
@@ -30,7 +30,6 @@  extern void		rx_expand_prologue (void);
 extern int		rx_initial_elimination_offset (int, int);
 
 #ifdef RTX_CODE
-extern bool		rx_compare_redundant (rtx);
 extern void             rx_emit_stack_popm (rtx *, bool);
 extern void             rx_emit_stack_pushm (rtx *);
 extern void		rx_expand_epilogue (bool);
diff --git a/gcc/config/rx/rx.c b/gcc/config/rx/rx.c
index b5a996f..9a163fe 100644
--- a/gcc/config/rx/rx.c
+++ b/gcc/config/rx/rx.c
@@ -2602,155 +2602,6 @@  flags_from_mode (enum machine_mode mode)
     }
 }
 
-/* Returns true if a compare insn is redundant because it
-   would only set flags that are already set correctly.  */
-
-bool
-rx_compare_redundant (rtx cmp)
-{
-  unsigned int flags_needed;
-  unsigned int flags_set;
-  rtx next;
-  rtx prev;
-  rtx source;
-  rtx dest;
-  static rtx cc_reg = NULL_RTX;
-
-  if (cc_reg == NULL_RTX)
-    cc_reg = gen_rtx_REG (CCmode, CC_REGNUM);
-
-  /* We can only eliminate compares against 0.  */
-  if (GET_CODE (XEXP (SET_SRC (PATTERN (cmp)), 1)) != CONST_INT
-      || INTVAL (XEXP (SET_SRC (PATTERN (cmp)), 1)) != 0)
-    return false;
-
-  /* Locate the branch insn that follows the
-     compare and which tests the bits in the PSW.  */
-  next = cmp;
-  do
-    {
-      /* If we have found an insn that sets or clobbers the CC
-	 register and it was not the IF_THEN_ELSE insn that we
-	 are looking for, then the comparison is redundant.  */
-      if (next != cmp && reg_mentioned_p (cc_reg, PATTERN (next)))
-	return true;
-
-      next = next_nonnote_insn (next);
-
-      /* If we run out of insns without finding the
-	 user then the comparison is unnecessary.  */
-      if (next == NULL_RTX)
-	return true;
-
-      /* If we have found another comparison
-	 insn then the first one is redundant.  */
-      if (INSN_P (next)
-	  && GET_CODE (PATTERN (next)) == SET
-	  && REG_P (SET_DEST (PATTERN (next)))
-	  && REGNO (SET_DEST (PATTERN (next))) == CC_REGNUM)
-	return true;
-
-      /* If we have found another arithmetic/logic insn that
-	 sets the PSW flags then the comparison is redundant.  */
-      if (INSN_P (next)
-	  && GET_CODE (PATTERN (next)) == PARALLEL
-	  && GET_CODE (XVECEXP (PATTERN (next), 0, 1)) == SET
-	  && REG_P (SET_DEST (XVECEXP (PATTERN (next), 0, 1)))
-	  && REGNO (SET_DEST (XVECEXP (PATTERN (next), 0, 1))) == CC_REGNUM)
-	return true;
-
-      /* If we have found an unconditional branch then the
-	 PSW flags might be carried along with the jump, so
-	 the comparison is necessary.  */
-      if (INSN_P (next) && JUMP_P (next))
-	{
-	  if (GET_CODE (PATTERN (next)) != SET)
-	    /* If the jump does not involve setting the PC
-	       then it is a return of some kind, and we know
-	       that the comparison is not used.  */
-	    return true;
-
-	  if (GET_CODE (SET_SRC (PATTERN (next))) != IF_THEN_ELSE)
-	    return false;
-	}
-    }
-  while (! INSN_P (next)
-	 || DEBUG_INSN_P (next)
-	 || GET_CODE (PATTERN (next)) != SET
-	 || GET_CODE (SET_SRC (PATTERN (next))) != IF_THEN_ELSE);
-
-  flags_needed = flags_needed_for_conditional (XEXP (SET_SRC (PATTERN (next)), 0));
-
-  /* Now look to see if there was a previous
-     instruction which set the PSW bits.  */
-  source = XEXP (SET_SRC (PATTERN (cmp)), 0);
-  prev = cmp;
-  do
-    {
-      /* If this insn uses/sets/clobbers the CC register
-	 and it is not the insn that we are looking for
-	 below, then we must need the comparison.  */
-      if (prev != cmp && reg_mentioned_p (cc_reg, PATTERN (prev)))
-	return false;
-
-      prev = prev_nonnote_insn (prev);
-
-      if (prev == NULL_RTX)
-	return false;
-
-      /* If we encounter an insn which changes the contents of
-	 the register which is the source of the comparison then
-	 we will definitely need the comparison.  */
-      if (INSN_P (prev)
-	  && GET_CODE (PATTERN (prev)) == SET
-	  && rtx_equal_p (SET_DEST (PATTERN (prev)), source))
-	{
-	  /* Unless this instruction is a simple register move
-	     instruction.  In which case we can continue our
-	     scan backwards, but now using the *source* of this
-	     set instruction.  */
-	  if (REG_P (SET_SRC (PATTERN (prev))))
-	    source = SET_SRC (PATTERN (prev));
-	  /* We can also survive a sign-extension if the test is
-	     for EQ/NE.  Note the same does not apply to zero-
-	     extension as this can turn a non-zero bit-pattern
-	     into zero.  */
-	  else if (flags_needed == CC_FLAG_Z
-		   && GET_CODE (SET_SRC (PATTERN (prev))) == SIGN_EXTEND)
-	    source = XEXP (SET_SRC (PATTERN (prev)), 0);
-	  else
-	    return false;
-	}
-
-      /* A label means a possible branch into the
-	 code here, so we have to stop scanning.  */
-      if (LABEL_P (prev))
-	return false;
-    }
-  while (! INSN_P (prev)
-	 || DEBUG_INSN_P (prev)
-	 || GET_CODE (PATTERN (prev)) != PARALLEL
-	 || GET_CODE (XVECEXP (PATTERN (prev), 0, 1)) != SET
-	 || ! REG_P (SET_DEST (XVECEXP (PATTERN (prev), 0, 1)))
-	 || REGNO (SET_DEST (XVECEXP (PATTERN (prev), 0, 1))) != CC_REGNUM);
-
-  flags_set = flags_from_mode (GET_MODE (SET_DEST (XVECEXP (PATTERN (prev), 0, 1))));
-
-  dest = SET_DEST (XVECEXP (PATTERN (prev), 0, 0));
-  /* The destination of the previous arithmetic/logic instruction
-     must match the source in the comparison operation.  For registers
-     we ignore the mode as there may have been a sign-extension involved.  */
-  if (! rtx_equal_p (source, dest))
-    {
-      if (REG_P (source) && REG_P (dest) && REGNO (dest) == REGNO (source))
-	;
-      else
-	return false;
-    }
-
-  return ((flags_set & flags_needed) == flags_needed);
-}
-
 static int
 rx_memory_move_cost (enum machine_mode mode, reg_class_t regclass, bool in)
 {
diff --git a/gcc/config/rx/rx.md b/gcc/config/rx/rx.md
index e0271d6..545c2fb 100644
--- a/gcc/config/rx/rx.md
+++ b/gcc/config/rx/rx.md
@@ -340,12 +340,7 @@ 
 	(compare:CC (match_operand:SI 0 "register_operand"  "r,r,r,r,r,r,r")
 		    (match_operand:SI 1 "rx_source_operand" "r,Uint04,Int08,Sint16,Sint24,i,Q")))]
   ""
-  {
-    rx_float_compare_mode = false;
-    if (rx_compare_redundant (insn))
-      return "; Compare Eliminated: cmp %Q1, %0";
-    return "cmp\t%Q1, %0";
-  }
+  "cmp\t%Q1, %0"
   [(set_attr "timings" "11,11,11,11,11,11,33")
    (set_attr "length"  "2,2,3,4,5,6,5")]
 )