* expr.c (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: For a bit-field

	destination type, extract only the valid bits if the source type is not
	integral and has a different mode.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@207902 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 62 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a71885409b3..eca2f7a780b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2014-02-19  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* expr.c (expand_expr_real_1) <case VIEW_CONVERT_EXPR>: For a bit-field
+	destination type, extract only the valid bits if the source type is not
+	integral and has a different mode.
+
 2014-02-19  Richard Biener  <rguenther@suse.de>
 
 	PR ipa/60243
diff --git a/gcc/expr.c b/gcc/expr.c
index 29ce694704c..be62c539e25 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -10436,6 +10436,11 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
       else if (INTEGRAL_TYPE_P (type) && INTEGRAL_TYPE_P (TREE_TYPE (treeop0)))
 	op0 = convert_modes (mode, GET_MODE (op0), op0,
 			     TYPE_UNSIGNED (TREE_TYPE (treeop0)));
+      /* If the output type is a bit-field type, do an extraction.  */
+      else if (reduce_bit_field)
+	return extract_bit_field (op0, TYPE_PRECISION (type), 0,
+				  TYPE_UNSIGNED (type), NULL_RTX,
+				  mode, mode);
       /* As a last resort, spill op0 to memory, and reload it in a
 	 different mode.  */
       else if (!MEM_P (op0))
@@ -10458,10 +10463,10 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
 	  op0 = target;
 	}
 
-      /* At this point, OP0 is in the correct mode.  If the output type is
-	 such that the operand is known to be aligned, indicate that it is.
-	 Otherwise, we need only be concerned about alignment for non-BLKmode
-	 results.  */
+      /* If OP0 is (now) a MEM, we need to deal with alignment issues.  If the
+	 output type is such that the operand is known to be aligned, indicate
+	 that it is.  Otherwise, we need only be concerned about alignment for
+	 non-BLKmode results.  */
       if (MEM_P (op0))
 	{
 	  enum insn_code icode;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a7aa8c2f9d1..c34f640710b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2014-02-19  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/opt31.adb: New test.
+
 2014-02-19  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* gcc.dg/torture/pr60092.c: xfail execution on *-*-solaris2.11* at -O0.
diff --git a/gcc/testsuite/gnat.dg/opt31.adb b/gcc/testsuite/gnat.dg/opt31.adb
new file mode 100644
index 00000000000..51aa3556cec
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt31.adb
@@ -0,0 +1,43 @@
+-- { dg-do run }
+-- { dg-options "-O" }
+
+with Interfaces; use Interfaces;
+with Unchecked_Conversion;
+
+procedure Opt31 is
+
+  type Unsigned_24 is new Unsigned_32 range 0 .. 2**24 - 1;
+  subtype Time_T is Unsigned_24 range 0 .. 24 * 60 * 60 * 128 - 1;
+
+  type Messages_T is array (Positive range <>) of Unsigned_8;
+  subtype T_3Bytes is Messages_T (1 .. 3);
+
+  type Rec1 is record
+    F : Time_T;
+  end record;
+  for Rec1 use record
+    F at 0 range 0 .. 23;
+  end record;
+  for Rec1'Size use 24;
+
+  type Rec2 is record
+    I1,I2,I3,I4 : Integer;
+    R1 : Rec1;
+  end record;
+
+  function Conv is new Unchecked_Conversion (T_3Bytes, Rec1);
+
+  procedure Decode (M : Messages_T) is
+    My_Rec2 : Rec2;
+  begin
+    My_Rec2.R1 := Conv (M (1 .. 3));
+    if not My_Rec2.R1.F'Valid then
+      raise Program_Error;
+    end if;
+  end;
+
+  Message : Messages_T (1 .. 4) := (16#18#, 16#0C#, 16#0C#, 16#18#);
+
+begin
+  Decode (Message);
+end;