[50/77] Add helper routines for SUBREG_PROMOTED_VAR_P subregs

When subregs contain promoted values, as indicated by
SUBREG_PROMOTED_VAR_P, both the unpromoted (outer) and
promoted (inner) values are known to be scalar integers.
This patch adds helper routines that get the modes as
scalar_int_modes.

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* rtl.h (subreg_unpromoted_mode, subreg_promoted_mode): New functions.
	* expr.c (convert_move): Use them.
	(convert_modes): Likewise.
	(store_expr_with_bounds): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r251502

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/rtl.h b/gcc/rtl.h
index 9e16b9b1..8f4c1fa 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -2764,6 +2764,24 @@ unwrap_const_vec_duplicate (T x)
   return x;
 }
 
+/* Return the unpromoted (outer) mode of SUBREG_PROMOTED_VAR_P subreg X.  */
+
+inline scalar_int_mode
+subreg_unpromoted_mode (rtx x)
+{
+  gcc_checking_assert (SUBREG_PROMOTED_VAR_P (x));
+  return as_a <scalar_int_mode> (GET_MODE (x));
+}
+
+/* Return the promoted (inner) mode of SUBREG_PROMOTED_VAR_P subreg X.  */
+
+inline scalar_int_mode
+subreg_promoted_mode (rtx x)
+{
+  gcc_checking_assert (SUBREG_PROMOTED_VAR_P (x));
+  return as_a <scalar_int_mode> (GET_MODE (SUBREG_REG (x)));
+}
+
 /* In emit-rtl.c */
 extern rtvec gen_rtvec_v (int, rtx *);
 extern rtvec gen_rtvec_v (int, rtx_insn **);