Merge lp:~ams-codesourcery/gcc-linaro/lp641397-4.6 into lp:gcc-linaro/4.6

[Andrew Stubbs]

This patch has been posted for upstream review here:
 http://old.nabble.com/-patch,-CSE--Bit-field-insertion-optimization-to30418376.html

The patch needs follow up. It's not obvious that it will ever be acceptable. I'm posting this merge request so as not to lose it.

Unmerged revisions

105757. By Andrew Stubbs on 2011-01-11

Fix a missed optimization in bitfield initialization.

LP:641397

=== added file 'ChangeLog.linaro'
--- ChangeLog.linaro	1970-01-01 00:00:00 +0000
+++ ChangeLog.linaro	2011-01-31 15:39:37 +0000
@@ -0,0 +1,8 @@
[phone]  Andrew Stubbs  <[e-mail]>
+
+	gcc/
+	* cse.c (cse_insn): Add support for ZERO_EXTRACT with a register
+	source operand.
+	* passes.c (init_optimization_passes): Move initialize_regs
+	before cse2.
+

=== modified file 'gcc/cse.c'
--- gcc/cse.c	2010-10-14 07:17:54 +0000
+++ gcc/cse.c	2011-01-31 15:39:37 +0000
@@ -5036,7 +5036,6 @@
 	     (set (zero_extract:M2 (reg:M N) (const_int C) (const_int D))
 		  (reg:M2 O)).  */
 	  if (GET_CODE (SET_DEST (sets[i].rtl)) == ZERO_EXTRACT
-	      && CONST_INT_P (trial)
 	      && CONST_INT_P (XEXP (SET_DEST (sets[i].rtl), 1))
 	      && CONST_INT_P (XEXP (SET_DEST (sets[i].rtl), 2))
 	      && REG_P (XEXP (SET_DEST (sets[i].rtl), 0))
@@ -5052,9 +5051,26 @@
 	      unsigned int dest_hash = HASH (dest_reg, GET_MODE (dest_reg));
 	      struct table_elt *dest_elt
 		= lookup (dest_reg, dest_hash, GET_MODE (dest_reg));
-	      rtx dest_cst = NULL;
-
-	      if (dest_elt)
+	      rtx dest_cst = NULL, src_cst = NULL;
+
+	      if (CONST_INT_P (trial))
+		 src_cst = trial;
+	      else if (REG_P (trial))
+		{
+		  unsigned int src_hash = HASH (trial, GET_MODE (trial));
+		  struct table_elt *src_elt
+		    = lookup (trial, src_hash, GET_MODE (trial));
+
+		  if (src_elt)
+		    for (p = src_elt->first_same_value; p; p = p->next_same_value)
+		      if (p->is_const && CONST_INT_P (p->exp))
+			{
+			  src_cst = p->exp;
+			  break;
+			}
+		}
+
+	      if (src_cst && dest_elt)
 		for (p = dest_elt->first_same_value; p; p = p->next_same_value)
 		  if (p->is_const && CONST_INT_P (p->exp))
 		    {
@@ -5076,7 +5092,7 @@
 		  else
 		    mask = ((HOST_WIDE_INT) 1 << INTVAL (width)) - 1;
 		  val &= ~(mask << shift);
-		  val |= (INTVAL (trial) & mask) << shift;
+		  val |= (INTVAL (src_cst) & mask) << shift;
 		  val = trunc_int_for_mode (val, GET_MODE (dest_reg));
 		  validate_unshare_change (insn, &SET_DEST (sets[i].rtl),
 					   dest_reg, 1);

=== modified file 'gcc/passes.c'
--- gcc/passes.c	2010-11-29 14:09:41 +0000
+++ gcc/passes.c	2011-01-31 15:39:37 +0000
@@ -990,11 +990,11 @@
 	}
       NEXT_PASS (pass_web);
       NEXT_PASS (pass_rtl_cprop);
+      NEXT_PASS (pass_initialize_regs);
       NEXT_PASS (pass_cse2);
       NEXT_PASS (pass_rtl_dse1);
       NEXT_PASS (pass_rtl_fwprop_addr);
       NEXT_PASS (pass_inc_dec);
-      NEXT_PASS (pass_initialize_regs);
       NEXT_PASS (pass_ud_rtl_dce);
       NEXT_PASS (pass_combine);
       NEXT_PASS (pass_if_after_combine);