re PR rtl-optimization/54457 ([x32] Fail to combine 64bit index + constant)

        PR rtl-optimization/54457
        * simplify-rtx.c (simplify_subreg):
	Simplify (subreg:M (op:N ((x:N) (y:N)), 0)
     	to (op:M (subreg:M (x:N) 0) (subreg:M (x:N) 0)), where
	the outer subreg is effectively a truncation to the original mode M.

testsuite/ChangeLog:

        PR rtl-optimization/54457
        * gcc.target/i386/pr54457.c: New test.

From-SVN: r191928

4 files changed, 53 insertions, 9 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2684193..f543b7b8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2012-10-01  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR rtl-optimization/54457
+	* simplify-rtx.c (simplify_subreg):
+	Simplify (subreg:M (op:N ((x:N) (y:N)), 0)
+	to (op:M (subreg:M (x:N) 0) (subreg:M (x:N) 0)), where
+	the outer subreg is effectively a truncation to the original mode M.
+
 2012-10-01  Richard Guenther  <rguenther@suse.de>
 
 	* builtins.def (ATTR_MATHFN_FPROUNDING): Do not use no-vops
@@ -299,7 +307,8 @@
 
 	Undo r185605 (mostly):
 	* config/avr/avr-protos.h (avr_load_lpm): Remove.
-	* config/avr/avr.c (avr_load_libgcc_p): Don't restrict to __flash loads.
+	* config/avr/avr.c (avr_load_libgcc_p): Don't restrict to __flash
+	loads.
 	(avr_out_lpm): Also handle loads > 1 byte.
 	(avr_load_lpm): Remove.
 	(avr_find_unused_d_reg): New static function.
@@ -367,8 +376,7 @@
 
 	PR target/54703
 	* simplify-rtx.c (simplify_binary_operation_1): Perform
-	(x - (x & y)) -> (x & ~y) optimization only for integral
-	modes.
+	(x - (x & y)) -> (x & ~y) optimization only for integral modes.
 
 2012-09-27  Marc Glisse  <marc.glisse@inria.fr>
 
@@ -527,7 +535,7 @@
 	PR target/54641
 	* config/avr/t-avr: Use ALL_COMPILERFLAGS instead of ALL_CFLAGS
 	for sources compiled with COMPILER.
-	
+
 2012-09-25  Richard Guenther  <rguenther@suse.de>
 
 	PR lto/54625
@@ -541,8 +549,7 @@
 	one bit precision properly.
 
 	PR other/54692
-	* configure.ac (CFLAGS, CXXFLAGS): Remove -Ofast or -Og
-	properly.
+	* configure.ac (CFLAGS, CXXFLAGS): Remove -Ofast or -Og properly.
 	* configure: Regenerated.
 
 2012-09-25  Georg-Johann Lay  <avr@gjlay.de>
@@ -564,8 +571,7 @@
 
 2012-09-24  Dehao Chen  <dehao@google.com>
 
-	* tree-cfg.c (move_stmt_op): Reset the expr block only
-	when necessary.
+	* tree-cfg.c (move_stmt_op): Reset the expr block only when necessary.
 	(move_block_to_fn): Reset the edge's goto block even
 	when the goto locus is unknown.
 
@@ -672,7 +678,7 @@
 
 2012-09-24  Janis Johnson  <janisjo@codesourcery.com>
 
-	doc/sourcebuild.texi (Selectors): Document the use of target
+	* doc/sourcebuild.texi (Selectors): Document the use of target
 	and xfail used together.
 
 2012-09-24  Richard Guenther  <rguenther@suse.de>
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index aebe6bb..c3e8a0a 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -5724,6 +5724,28 @@ simplify_subreg (enum machine_mode outermode, rtx op,
 	return CONST0_RTX (outermode);
     }
 
+  /* Simplify (subreg:SI (op:DI ((x:DI) (y:DI)), 0)
+     to (op:SI (subreg:SI (x:DI) 0) (subreg:SI (x:DI) 0)), where
+     the outer subreg is effectively a truncation to the original mode.  */
+  if ((GET_CODE (op) == PLUS
+       || GET_CODE (op) == MINUS
+       || GET_CODE (op) == MULT)
+      && SCALAR_INT_MODE_P (outermode)
+      && SCALAR_INT_MODE_P (innermode)
+      && GET_MODE_PRECISION (outermode) < GET_MODE_PRECISION (innermode)
+      && byte == subreg_lowpart_offset (outermode, innermode))
+    {
+      rtx op0 = simplify_gen_subreg (outermode, XEXP (op, 0),
+                                     innermode, byte);
+      if (op0)
+        {
+          rtx op1 = simplify_gen_subreg (outermode, XEXP (op, 1),
+                                         innermode, byte);
+          if (op1)
+            return simplify_gen_binary (GET_CODE (op), outermode, op0, op1);
+        }
+    }
+
   /* Simplify (subreg:QI (lshiftrt:SI (sign_extend:SI (x:QI)) C), 0) into
      to (ashiftrt:QI (x:QI) C), where C is a suitable small constant and
      the outer subreg is effectively a truncation to the original mode.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0cd1176..89d7eeb 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-10-01  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR rtl-optimization/54457
+	* gcc.target/i386/pr54457.c: New test.
+
 2012-10-01  Ulrich Weigand  <ulrich.weigand@linaro.org>
 
 	* gcc.dg/lower-subreg-1.c: Disable on arm*-*-* targets.
diff --git a/gcc/testsuite/gcc.target/i386/pr54457.c b/gcc/testsuite/gcc.target/i386/pr54457.c
new file mode 100644
index 0000000..d27f899
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr54457.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { ! { ia32 } } } } */
+/* { dg-options "-O2 -mx32 -maddress-mode=short" } */
+
+extern char array[40];
+
+char foo (long long position)
+{
+  return array[position + 1];
+}
+
+/* { dg-final { scan-assembler-not "add\[lq\]?\[^\n\]*1" } } */