[arm] Remove mode26 feature bit

    * config/arm/arm-cpus.in (mode26): Delete.
    (armv4): Delete mode26 reference.
    * config/arm/arm.c (arm_configure_build_target): Delete use of
    isa_bit_mode26.

From-SVN: r260615

gcc/ChangeLog

+2018-05-23  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	* config/arm/arm-cpus.in (mode26): Delete.
+	(armv4): Delete mode26 reference.
+	* config/arm/arm.c (arm_configure_build_target): Delete use of
+	isa_bit_mode26.
+
 2018-05-23  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.md (*floatuns<SWI48:mode><MODEF:mode>2_avx512):

gcc/config/arm/arm-cpus.in

@@ -48,9 +48,6 @@
 
 # Features - general convention: all lower case.
 
-# 26-bit mode support
-define feature mode26
-
 # Architecture rel 4
 define feature armv4
 
@@ -274,11 +271,9 @@ begin arch armv4
  tune for arm7tdmi
  tune flags CO_PROC
  base 4
- isa ARMv4 mode26
+ isa ARMv4
 end arch armv4
 
-# Strictly, mode26 is a permitted option for v4t, but there are no
-# implementations that support it, so we will leave it out for now.
 begin arch armv4t
  tune for arm7tdmi
  tune flags CO_PROC

gcc/config/arm/arm.c

@@ -3232,16 +3232,7 @@ arm_configure_build_target (struct arm_build_target *target,
 	 switches that require certain abilities from the cpu.  */
 
       if (TARGET_INTERWORK || TARGET_THUMB)
-	{
-	  bitmap_set_bit (sought_isa, isa_bit_thumb);
-
-	  /* There are no ARM processors that support both APCS-26 and
-	     interworking.  Therefore we forcibly remove MODE26 from
-	     from the isa features here (if it was set), so that the
-	     search below will always be able to find a compatible
-	     processor.  */
-	  bitmap_clear_bit (default_isa, isa_bit_mode26);
-	}
+	bitmap_set_bit (sought_isa, isa_bit_thumb);
 
       /* If there are such requirements and the default CPU does not
 	 satisfy them, we need to run over the complete list of