PR target/37382

	* expmed.c (extract_low_bits): Avoid creating invalid subregs.
	* dse.c (find_shift_sequence): Use extract_low_bits instead of
	simplify_gen_subreg.

	* gcc.c-torture/compile/pr37382.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@140265 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 6 insertions, 6 deletions

diff --git a/gcc/dse.c b/gcc/dse.c
index 7283bbe67e4..0a3ebb40ffa 100644
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -1445,7 +1445,7 @@ find_shift_sequence (int access_size,
        new_mode = GET_MODE_WIDER_MODE (new_mode))
     {
       rtx target, new_reg, shift_seq, insn, new_lhs;
-      int cost, offset;
+      int cost;
 
       /* Try a wider mode if truncating the store mode to NEW_MODE
 	 requires a real instruction.  */
@@ -1459,11 +1459,6 @@ find_shift_sequence (int access_size,
       if (!CONSTANT_P (store_info->rhs)
 	  && !MODES_TIEABLE_P (new_mode, store_mode))
 	continue;
-      offset = subreg_lowpart_offset (new_mode, store_mode);
-      new_lhs = simplify_gen_subreg (new_mode, copy_rtx (store_info->rhs),
-				     store_mode, offset);
-      if (new_lhs == NULL_RTX)
-	continue;
 
       new_reg = gen_reg_rtx (new_mode);
 
@@ -1496,6 +1491,11 @@ find_shift_sequence (int access_size,
       if (cost > COSTS_N_INSNS (1))
 	continue;
 
+      new_lhs = extract_low_bits (new_mode, store_mode,
+				  copy_rtx (store_info->rhs));
+      if (new_lhs == NULL_RTX)
+	continue;
+
       /* We found an acceptable shift.  Generate a move to
 	 take the value from the store and put it into the
 	 shift pseudo, then shift it, then generate another