* lower-subreg.c (subreg_context): New static bitmap.

	(decompose_multiword_subregs): Allocate and free it.
	(find_decomposable_subregs): Set a bit in it for a register that
	occurs in a subreg that changes mode but not size.
	(can_decompose_p): Test it instead of non_decomposable_context.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@162181 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index daa007a372fdd2799f4bcb714df2a34f42799ca7..e894e6236458bd6bf6d121799f3498906d7e902c 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2010-07-14  Bernd Schmidt  <bernds@codesourcery.com>
+
+       * lower-subreg.c (subreg_context): New static bitmap.
+       (decompose_multiword_subregs): Allocate and free it.
+       (find_decomposable_subregs): Set a bit in it for a register that
+       occurs in a subreg that changes mode but not size.
+       (can_decompose_p): Test it instead of non_decomposable_context.
+
 2010-07-14  Richard Guenther  <rguenther@suse.de>
 
        PR tree-optimization/44824

diff --git a/gcc/lower-subreg.c b/gcc/lower-subreg.c
index 160328ccefcc1e995ac90c19600ac6f90994db28..1cc972ac72d0af350e60d3fc287a680264a59260 100644 (file)
--- a/gcc/lower-subreg.c
+++ b/gcc/lower-subreg.c
@@ -63,6 +63,12 @@ static bitmap decomposable_context;
    which it can not be decomposed.  */
 static bitmap non_decomposable_context;
 
+/* Bit N in this bitmap is set if regno N is used in a subreg
+   which changes the mode but not the size.  This typically happens
+   when the register accessed as a floating-point value; we want to
+   avoid generating accesses to its subwords in integer modes.  */
+static bitmap subreg_context;
+
 /* Bit N in the bitmap in element M of this array is set if there is a
    copy from reg M to reg N.  */
 static VEC(bitmap,heap) *reg_copy_graph;
@@ -289,6 +295,7 @@ find_decomposable_subregs (rtx *px, void *data)
          && !MODES_TIEABLE_P (GET_MODE (x), GET_MODE (inner)))
        {
          bitmap_set_bit (non_decomposable_context, regno);
+         bitmap_set_bit (subreg_context, regno);
          return -1;
        }
     }
@@ -616,7 +623,7 @@ can_decompose_p (rtx x)
        return (validate_subreg (word_mode, GET_MODE (x), x, UNITS_PER_WORD)
                && HARD_REGNO_MODE_OK (regno, word_mode));
       else
-       return !bitmap_bit_p (non_decomposable_context, regno);
+       return !bitmap_bit_p (subreg_context, regno);
     }
 
   return true;
@@ -1091,6 +1098,7 @@ decompose_multiword_subregs (void)
 
   decomposable_context = BITMAP_ALLOC (NULL);
   non_decomposable_context = BITMAP_ALLOC (NULL);
+  subreg_context = BITMAP_ALLOC (NULL);
 
   reg_copy_graph = VEC_alloc (bitmap, heap, max);
   VEC_safe_grow (bitmap, heap, reg_copy_graph, max);
@@ -1309,6 +1317,7 @@ decompose_multiword_subregs (void)
 
   BITMAP_FREE (decomposable_context);
   BITMAP_FREE (non_decomposable_context);
+  BITMAP_FREE (subreg_context);
 }
 \f
 /* Gate function for lower subreg pass.  */