Rip out rhs-to-tree from tree-affine.c

After the previous cleanup the following is more straight-forward now.
This should make tree-affine behave wrt the "new" GIMPLE world.

Bootstrapped and tested on x86_64-unknown-linux-gnu, now making
sure there are no codegen changes as expected.

Richard.

2018-12-11  Richard Biener  <rguenther@suse.de>

	* tree-affine.c (expr_to_aff_combination): New function split
	out from...
	(tree_to_aff_combination): ... here.
	(aff_combination_expand): Avoid building a GENERIC tree.

On Tue, 11 Dec 2018, Richard Biener wrote:

> 
> After the previous cleanup the following is more straight-forward now.
> This should make tree-affine behave wrt the "new" GIMPLE world.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu, now making
> sure there are no codegen changes as expected.

So this is the final patch.  It generates the same code for gcc/*.o
besides one case where it improved code-generation slightly.
Unfortunately it regresses

FAIL: gcc.dg/tree-ssa/ivopts-lt-2.c scan-tree-dump-times ivopts "PHI" 1
FAIL: gcc.dg/tree-ssa/ivopts-lt-2.c scan-tree-dump-times ivopts "p_[0-9]* <" 1

on x86_64 where IVOPTs fails to eliminate one induction variable.
This is because we no longer expand

 {
   type = long unsigned int
   offset = 0
   elements = {
     [0] = _1 * 4
   }
 }

to

 {
   type = long unsigned int
   offset = 0
   elements = {
     [0] = (long unsigned int) i_6(D) * 1
   }
 }
 
which I think is reasonable.  This has to be dealt with in
IVOPTs.  On 32bit the testcase still passes.

I do not want to introduce a regression at this point
so I am defering this patch to GCC 10.

Developing this patch also exposed IVOPTs calling
tree_to_aff_combination with essentially an outer
widenig cast missing which required to do

+    CASE_CONVERT:
+      if (expr_to_aff_combination (comb, code,
+                                  TREE_TYPE (expr), TREE_OPERAND (expr, 0)))
+       {
+         aff_combination_convert (comb, type);
+         return;

which shouldn'd be required.  That's also sth to fix
and there's now plenty of time in the GCC 10 timeframe to
do so.

Bootstrapped / tested on x86_64-unknown-linux-gnu.

Richard.

2018-12-21  Richard Biener  <rguenther@suse.de>

	* tree-affine.c (expr_to_aff_combination): New function split
	out from...
	(tree_to_aff_combination): ... here.
	(aff_combination_expand): Avoid building a GENERIC tree.


Index: gcc/tree-affine.c
===================================================================
--- gcc/tree-affine.c	(revision 267297)
+++ gcc/tree-affine.c	(working copy)
@@ -259,104 +259,66 @@ aff_combination_convert (aff_tree *comb,
     }
 }
 
-/* Splits EXPR into an affine combination of parts.  */
+/* Tries to handle OP0 CODE OP1 as affine combination of parts.  Returns
+   true when that was successful and returns the combination in COMB.  */
 
-void
-tree_to_aff_combination (tree expr, tree type, aff_tree *comb)
+static bool
+expr_to_aff_combination (aff_tree *comb, tree_code code, tree type,
+			 tree op0, tree op1 = NULL_TREE)
 {
   aff_tree tmp;
-  enum tree_code code;
-  tree cst, core, toffset;
   poly_int64 bitpos, bitsize, bytepos;
-  machine_mode mode;
-  int unsignedp, reversep, volatilep;
-
-  STRIP_NOPS (expr);
 
-  code = TREE_CODE (expr);
   switch (code)
     {
     case POINTER_PLUS_EXPR:
-      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
-      tree_to_aff_combination (TREE_OPERAND (expr, 1), sizetype, &tmp);
+      tree_to_aff_combination (op0, type, comb);
+      tree_to_aff_combination (op1, sizetype, &tmp);
       aff_combination_add (comb, &tmp);
-      return;
+      return true;
 
     case PLUS_EXPR:
     case MINUS_EXPR:
-      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
-      tree_to_aff_combination (TREE_OPERAND (expr, 1), type, &tmp);
+      tree_to_aff_combination (op0, type, comb);
+      tree_to_aff_combination (op1, type, &tmp);
       if (code == MINUS_EXPR)
 	aff_combination_scale (&tmp, -1);
       aff_combination_add (comb, &tmp);
-      return;
+      return true;
 
     case MULT_EXPR:
-      cst = TREE_OPERAND (expr, 1);
-      if (TREE_CODE (cst) != INTEGER_CST)
+      if (TREE_CODE (op1) != INTEGER_CST)
 	break;
-      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
-      aff_combination_scale (comb, wi::to_widest (cst));
-      return;
+      tree_to_aff_combination (op0, type, comb);
+      aff_combination_scale (comb, wi::to_widest (op1));
+      return true;
 
     case NEGATE_EXPR:
-      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
+      tree_to_aff_combination (op0, type, comb);
       aff_combination_scale (comb, -1);
-      return;
+      return true;
 
     case BIT_NOT_EXPR:
       /* ~x = -x - 1 */
-      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
+      tree_to_aff_combination (op0, type, comb);
       aff_combination_scale (comb, -1);
       aff_combination_add_cst (comb, -1);
-      return;
-
-    case ADDR_EXPR:
-      /* Handle &MEM[ptr + CST] which is equivalent to POINTER_PLUS_EXPR.  */
-      if (TREE_CODE (TREE_OPERAND (expr, 0)) == MEM_REF)
-	{
-	  expr = TREE_OPERAND (expr, 0);
-	  tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
-	  tree_to_aff_combination (TREE_OPERAND (expr, 1), sizetype, &tmp);
-	  aff_combination_add (comb, &tmp);
-	  return;
-	}
-      core = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize, &bitpos,
-				  &toffset, &mode, &unsignedp, &reversep,
-				  &volatilep);
-      if (!multiple_p (bitpos, BITS_PER_UNIT, &bytepos))
-	break;
-      aff_combination_const (comb, type, bytepos);
-      if (TREE_CODE (core) == MEM_REF)
-	{
-	  tree mem_offset = TREE_OPERAND (core, 1);
-	  aff_combination_add_cst (comb, wi::to_poly_widest (mem_offset));
-	  core = TREE_OPERAND (core, 0);
-	}
-      else
-	core = build_fold_addr_expr (core);
-
-      if (TREE_CODE (core) == ADDR_EXPR)
-	aff_combination_add_elt (comb, core, 1);
-      else
-	{
-	  tree_to_aff_combination (core, type, &tmp);
-	  aff_combination_add (comb, &tmp);
-	}
-      if (toffset)
-	{
-	  tree_to_aff_combination (toffset, type, &tmp);
-	  aff_combination_add (comb, &tmp);
-	}
-      return;
+      return true;
 
     CASE_CONVERT:
       {
-	tree otype = TREE_TYPE (expr);
-	tree inner = TREE_OPERAND (expr, 0);
+	tree otype = type;
+	tree inner = op0;
 	tree itype = TREE_TYPE (inner);
 	enum tree_code icode = TREE_CODE (inner);
 
+	/* STRIP_NOPS  */
+	if (tree_nop_conversion_p (otype, itype))
+	  {
+	    tree_to_aff_combination (op0, type, comb);
+	    return true;
+	  }
+
 	/* In principle this is a valid folding, but it isn't necessarily
 	   an optimization, so do it here and not in fold_unary.  */
 	if ((icode == PLUS_EXPR || icode == MINUS_EXPR || icode == MULT_EXPR)
@@ -376,9 +338,7 @@ tree_to_aff_combination (tree expr, tree
 	      {
 		op0 = fold_convert (otype, op0);
 		op1 = fold_convert (otype, op1);
-		expr = fold_build2 (icode, otype, op0, op1);
-		tree_to_aff_combination (expr, type, comb);
-		return;
+		return expr_to_aff_combination (comb, icode, otype, op0, op1);
 	      }
 	    wide_int minv, maxv;
 	    /* If inner type has wrapping overflow behavior, fold conversion
@@ -399,15 +359,100 @@ tree_to_aff_combination (tree expr, tree
 		  {
 		    op0 = fold_convert (otype, op0);
 		    op1 = fold_convert (otype, op1);
-		    expr = fold_build2 (MINUS_EXPR, otype, op0, op1);
-		    tree_to_aff_combination (expr, type, comb);
-		    return;
+		    return expr_to_aff_combination (comb, MINUS_EXPR, otype,
+						    op0, op1);
 		  }
 	      }
 	  }
       }
       break;
 
+    default:;
+    }
+
+  return false;
+}
+
+/* Splits EXPR into an affine combination of parts.  */
+
+void
+tree_to_aff_combination (tree expr, tree type, aff_tree *comb)
+{
+  aff_tree tmp;
+  enum tree_code code;
+  tree core, toffset;
+  poly_int64 bitpos, bitsize, bytepos;
+  machine_mode mode;
+  int unsignedp, reversep, volatilep;
+
+  STRIP_NOPS (expr);
+
+  code = TREE_CODE (expr);
+  switch (code)
+    {
+    case POINTER_PLUS_EXPR:
+    case PLUS_EXPR:
+    case MINUS_EXPR:
+    case MULT_EXPR:
+      if (expr_to_aff_combination (comb, code, type, TREE_OPERAND (expr, 0),
+				   TREE_OPERAND (expr, 1)))
+	return;
+      break;
+
+    case NEGATE_EXPR:
+    case BIT_NOT_EXPR:
+      if (expr_to_aff_combination (comb, code, type, TREE_OPERAND (expr, 0)))
+	return;
+      break;
+
+    CASE_CONVERT:
+      if (expr_to_aff_combination (comb, code,
+				   TREE_TYPE (expr), TREE_OPERAND (expr, 0)))
+	{
+	  aff_combination_convert (comb, type);
+	  return;
+	}
+      break;
+
+    case ADDR_EXPR:
+      /* Handle &MEM[ptr + CST] which is equivalent to POINTER_PLUS_EXPR.  */
+      if (TREE_CODE (TREE_OPERAND (expr, 0)) == MEM_REF)
+	{
+	  expr = TREE_OPERAND (expr, 0);
+	  tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);
+	  tree_to_aff_combination (TREE_OPERAND (expr, 1), sizetype, &tmp);
+	  aff_combination_add (comb, &tmp);
+	  return;
+	}
+      core = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize, &bitpos,
+				  &toffset, &mode, &unsignedp, &reversep,
+				  &volatilep);
+      if (!multiple_p (bitpos, BITS_PER_UNIT, &bytepos))
+	break;
+      aff_combination_const (comb, type, bytepos);
+      if (TREE_CODE (core) == MEM_REF)
+	{
+	  tree mem_offset = TREE_OPERAND (core, 1);
+	  aff_combination_add_cst (comb, wi::to_poly_widest (mem_offset));
+	  core = TREE_OPERAND (core, 0);
+	}
+      else
+	core = build_fold_addr_expr (core);
+
+      if (TREE_CODE (core) == ADDR_EXPR)
+	aff_combination_add_elt (comb, core, 1);
+      else
+	{
+	  tree_to_aff_combination (core, type, &tmp);
+	  aff_combination_add (comb, &tmp);
+	}
+      if (toffset)
+	{
+	  tree_to_aff_combination (toffset, type, &tmp);
+	  aff_combination_add (comb, &tmp);
+	}
+      return;
+
     default:
       {
 	if (poly_int_tree_p (expr))
@@ -665,7 +710,7 @@ aff_combination_expand (aff_tree *comb A
 {
   unsigned i;
   aff_tree to_add, current, curre;
-  tree e, rhs;
+  tree e;
   gimple *def;
   widest_int scale;
   struct name_expansion *exp;
@@ -715,20 +760,27 @@ aff_combination_expand (aff_tree *comb A
 	    case PLUS_EXPR:
 	    case MINUS_EXPR:
 	    case MULT_EXPR:
+	      if (!expr_to_aff_combination (&current, code, TREE_TYPE (name),
+					    gimple_assign_rhs1 (def),
+					    gimple_assign_rhs2 (def)))
+		continue;
+	      break;
 	    case NEGATE_EXPR:
 	    case BIT_NOT_EXPR:
 	    CASE_CONVERT:
-	      rhs = gimple_assign_rhs_to_tree (def);
+	      if (!expr_to_aff_combination (&current, code, TREE_TYPE (name),
+					    gimple_assign_rhs1 (def)))
+		continue;
 	      break;
 	    case ADDR_EXPR:
 	    case INTEGER_CST:
 	    case POLY_INT_CST:
-	      rhs = gimple_assign_rhs1 (def);
+	      tree_to_aff_combination (gimple_assign_rhs1 (def),
+				       TREE_TYPE (name), &current);
 	      break;
 	    default:
 	      continue;
 	    }
-	  tree_to_aff_combination (rhs, TREE_TYPE (name), &current);
 	  exp = XNEW (struct name_expansion);
 	  exp->in_progress = 1;
 	  if (!*cache)