* simplify-rtx.c (simplify_unary_operation_1) <TRUNCATE>: When

	trying to remove TRUNCATE check if all bits outside the new mode
	are identical to the sign bit.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@112643 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b264035..d157632 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2006-04-03  Adam Nemet  <anemet@caviumnetworks.com>
+
+       * simplify-rtx.c (simplify_unary_operation_1) <TRUNCATE>: When
+       trying to remove TRUNCATE check if all bits outside the new mode
+       are identical to the sign bit.
+
 2006-04-03  Jeff Law  <law@redhat.com>
 
        * tree-ssa-dom.c (propagate_rhs_into_lhs): Avoid useless folding

diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index cac77ad..0ce033d 100644 (file)
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -656,7 +656,8 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
       if ((TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
                                 GET_MODE_BITSIZE (GET_MODE (op)))
           ? (num_sign_bit_copies (op, GET_MODE (op))
-             >= (unsigned int) (GET_MODE_BITSIZE (mode) + 1))
+             > (unsigned int) (GET_MODE_BITSIZE (GET_MODE (op))
+                               - GET_MODE_BITSIZE (mode)))
           : truncated_to_mode (mode, op))
          && ! (GET_CODE (op) == LSHIFTRT
                && GET_CODE (XEXP (op, 0)) == MULT))