From 6f9071656286512360ca22b6668c9c8d823ec907 Mon Sep 17 00:00:00 2001
From: Alan Lawrence <alan.lawrence@arm.com>
Date: Tue, 27 Oct 2015 12:36:55 +0000
Subject: tree-scalar-evolution.c: Handle LSHIFT by constant

gcc/:

	tree-scalar-evolution.c (interpret_rhs_expr): Handle some LSHIFT_EXPRs
	as equivalent MULT_EXPRs.

gcc/testsuite/:

	gcc.dg/vect/vect-strided-shift.c: New.

From-SVN: r229437
---
 gcc/tree-scalar-evolution.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'gcc/tree-scalar-evolution.c')

diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index 0753bf3..8e95ddd 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -1840,6 +1840,20 @@ interpret_rhs_expr (struct loop *loop, gimple *at_stmt,
       res = chrec_fold_multiply (type, chrec1, chrec2);
       break;
 
+    case LSHIFT_EXPR:
+      /* Handle A<<B as A * (1<<B).  */
+      chrec1 = analyze_scalar_evolution (loop, rhs1);
+      chrec2 = analyze_scalar_evolution (loop, rhs2);
+      chrec1 = chrec_convert (type, chrec1, at_stmt);
+      chrec1 = instantiate_parameters (loop, chrec1);
+      chrec2 = instantiate_parameters (loop, chrec2);
+
+      chrec2 = fold_build2 (LSHIFT_EXPR, type,
+			    build_int_cst (TREE_TYPE (rhs1), 1),
+			    chrec2);
+      res = chrec_fold_multiply (type, chrec1, chrec2);
+      break;
+
     CASE_CONVERT:
       /* In case we have a truncation of a widened operation that in
          the truncated type has undefined overflow behavior analyze
-- 
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