* combine.c (nonzero_bits, case PLUS): If pointers extend unsigned

	and this is the sum of a pointer and a constant, we know the result
	did not overflow.
	(num_sign_bit_copies, case PLUS): Likewise.
	* explow.c (convert_memory_address): Remove opposite SUBREG.
	* function.c (instantiate_new_reg): New function (from common code).
	(instantiate_virtual_regs_1): Call it.
	For PLUS, handle if (plus (subreg (virt-reg) (const_int))
	if pointers sign- or zero-extend.
	* simplify-rtx.c (simplify_unary_operation, case ZERO_EXTEND):
	If pointers extend unsigned, use inside of SUBREG.
	(simplify_unary_operation, case SIGN_EXTEND): Likewise, if sign extend.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@39489 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 5 insertions, 0 deletions

diff --git a/gcc/explow.c b/gcc/explow.c
index d36ceffa440..b7c0bb9f6d9 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -386,6 +386,11 @@ convert_memory_address (to_mode, x)
     case CONST_DOUBLE:
       return x;
 
+    case SUBREG:
+      if (GET_MODE (SUBREG_REG (x)) == to_mode)
+	return SUBREG_REG (x);
+      break;
+
     case LABEL_REF:
       temp = gen_rtx_LABEL_REF (to_mode, XEXP (x, 0));
       LABEL_REF_NONLOCAL_P (temp) = LABEL_REF_NONLOCAL_P (x);