or1k: Fix code quality for volatile memory loads

Volatile memory does not match the memory_operand predicate.  This
causes extra extend/mask instructions instructions when reading
from volatile memory.  On OpenRISC loading volatile memory can be
treated the same as regular memory loads which supports combined
sign/zero extends.  Fixing this eliminates the need for extra
extend/mask instructions.

This also adds a test provided by Richard Selvaggi which uncovered the
issue while we were looking into another issue.

gcc/ChangeLog:

	PR target/90363
	* config/or1k/or1k.md (zero_extend<mode>si2): Update predicate.
	(extend<mode>si2): Update predicate.
	* gcc/config/or1k/predicates.md (volatile_mem_operand): New.
	(reg_or_mem_operand): New.

gcc/testsuite/ChangeLog:

	PR target/90363
	* gcc.target/or1k/swap-1.c: New test.
	* gcc.target/or1k/swap-2.c: New test.

From-SVN: r273647

gcc/ChangeLog

+2019-07-22  Stafford Horne  <shorne@gmail.com>
+
+	PR target/90363
+	* config/or1k/or1k.md (zero_extend<mode>si2): Update predicate.
+	(extend<mode>si2): Update predicate.
+	* gcc/config/or1k/predicates.md (volatile_mem_operand): New.
+	(reg_or_mem_operand): New.
+
 2019-07-21  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* config/rs6000/rs6000.c (TARGET_NO_PROTOTYPE): Move from here...

gcc/config/or1k/or1k.md

@@ -328,11 +328,11 @@
 ;; Sign Extending
 ;; -------------------------------------------------------------------------
 
-;; Zero extension can always be done with AND and an extending load.
+;; Zero extension can always be done with AND or an extending load.
 
 (define_insn "zero_extend<mode>si2"
   [(set (match_operand:SI 0 "register_operand"                     "=r,r")
-	(zero_extend:SI (match_operand:I12 1 "nonimmediate_operand" "r,m")))]
+	(zero_extend:SI (match_operand:I12 1 "reg_or_mem_operand" "r,m")))]
   ""
   "@
    l.andi\t%0, %1, <zext_andi>
@@ -344,7 +344,7 @@
 
 (define_insn "extend<mode>si2"
   [(set (match_operand:SI 0 "register_operand"                      "=r,r")
-	(sign_extend:SI (match_operand:I12 1 "nonimmediate_operand"  "r,m")))]
+	(sign_extend:SI (match_operand:I12 1 "reg_or_mem_operand"  "r,m")))]
   "TARGET_SEXT"
   "@
    l.ext<ldst>s\t%0, %1

gcc/config/or1k/predicates.md

@@ -82,3 +82,21 @@
 
 (define_predicate "equality_comparison_operator"
   (match_code "ne,eq"))
+
+;; Borrowed from rs6000
+;; Return true if the operand is in volatile memory.  Note that during the
+;; RTL generation phase, memory_operand does not return TRUE for volatile
+;; memory references.  So this function allows us to recognize volatile
+;; references where it's safe.
+(define_predicate "volatile_mem_operand"
+  (and (match_code "mem")
+       (match_test "MEM_VOLATILE_P (op)")
+       (if_then_else (match_test "reload_completed")
+	 (match_operand 0 "memory_operand")
+	 (match_test "memory_address_p (mode, XEXP (op, 0))"))))
+
+;; Return true if the operand is a register or memory; including volatile
+;; memory.
+(define_predicate "reg_or_mem_operand"
+  (ior (match_operand 0 "nonimmediate_operand")
+       (match_operand 0 "volatile_mem_operand")))

gcc/testsuite/ChangeLog

+2019-07-22  Stafford Horne  <shorne@gmail.com>
+
+	PR target/90363
+	* gcc.target/or1k/swap-1.c: New test.
+	* gcc.target/or1k/swap-2.c: New test.
+
 2019-07-20  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* gcc.target/powerpc/volatile-mem.c: New testcase.