[gcc r13-1161] xtensa: Defer storing integer constants into litpool until reload

[gcc r13-1161] xtensa: Defer storing integer constants into litpool until reload

[Max Filippov]

https://gcc.gnu.org/g:479b6f449ee999501ad6eff0b7db8d0cd5b2d28d

commit r13-1161-g479b6f449ee999501ad6eff0b7db8d0cd5b2d28d
Author: Takayuki 'January June' Suwa <jjsuwa_sys3175@yahoo.co.jp>
Date:   Fri Jun 17 22:47:49 2022 +0900

    xtensa: Defer storing integer constants into litpool until reload
    
    Storing integer constants into litpool in the early stage of compilation
    hinders some integer optimizations.  In fact, such integer constants are
    not subject to the constant folding process.
    
    For example:
    
        extern unsigned short value;
        extern void foo(void);
        void test(void) {
          if (value == 30001)
            foo();
        }
    
            .literal_position
            .literal .LC0, value
            .literal .LC1, 30001
        test:
            l32r    a3, .LC0
            l32r    a2, .LC1
            l16ui   a3, a3, 0
            extui   a2, a2, 0, 16  // runtime zero-extension despite constant
            bne     a3, a2, .L1
            j.l     foo, a9
        .L1:
            ret.n
    
    This patch defers the placement of integer constants into litpool until
    the start of reload:
    
            .literal_position
            .literal .LC0, value
            .literal .LC1, 30001
        test:
            l32r    a3, .LC0
            l32r    a2, .LC1
            l16ui   a3, a3, 0
            bne     a3, a2, .L1
            j.l     foo, a9
        .L1:
            ret.n
    
    gcc/ChangeLog:
    
            * config/xtensa/constraints.md (Y):
            Change to include integer constants until reload begins.
            * config/xtensa/predicates.md (move_operand): Ditto.
            * config/xtensa/xtensa.cc (xtensa_emit_move_sequence):
            Change to allow storing integer constants into litpool only after
            reload begins.

Diff:
---
 gcc/config/xtensa/constraints.md | 6 ++++--
 gcc/config/xtensa/predicates.md  | 5 +++--
 gcc/config/xtensa/xtensa.cc      | 3 ++-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/gcc/config/xtensa/constraints.md b/gcc/config/xtensa/constraints.md
index e7ac8dbfebf..0b7dcd1440e 100644
--- a/gcc/config/xtensa/constraints.md
+++ b/gcc/config/xtensa/constraints.md
@@ -113,8 +113,10 @@
 
 (define_constraint "Y"
  "A constant that can be used in relaxed MOVI instructions."
- (and (match_code "const_int,const_double,const,symbol_ref,label_ref")
-      (match_test "TARGET_AUTO_LITPOOLS")))
+ (ior (and (match_code "const_int,const_double,const,symbol_ref,label_ref")
+	   (match_test "TARGET_AUTO_LITPOOLS"))
+      (and (match_code "const_int")
+	   (match_test "can_create_pseudo_p ()"))))
 
 ;; Memory constraints.  Do not use define_memory_constraint here.  Doing so
 ;; causes reload to force some constants into the constant pool, but since
diff --git a/gcc/config/xtensa/predicates.md b/gcc/config/xtensa/predicates.md
index edd13ae41b9..0590c0f81a9 100644
--- a/gcc/config/xtensa/predicates.md
+++ b/gcc/config/xtensa/predicates.md
@@ -147,8 +147,9 @@
 	       (match_test "!constantpool_mem_p (op)
 			    || GET_MODE_SIZE (mode) % UNITS_PER_WORD == 0")))
      (ior (and (match_code "const_int")
-	       (match_test "GET_MODE_CLASS (mode) == MODE_INT
-			    && xtensa_simm12b (INTVAL (op))"))
+	       (match_test "(GET_MODE_CLASS (mode) == MODE_INT
+			     && xtensa_simm12b (INTVAL (op)))
+			    || can_create_pseudo_p ()"))
 	  (and (match_code "const_int,const_double,const,symbol_ref,label_ref")
 	       (match_test "(TARGET_CONST16 || TARGET_AUTO_LITPOOLS)
 			    && CONSTANT_P (op)
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index d6f08b11648..c5d00acdf2c 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -1182,7 +1182,8 @@ xtensa_emit_move_sequence (rtx *operands, machine_mode mode)
 	  return 1;
 	}
 
-      if (! TARGET_AUTO_LITPOOLS && ! TARGET_CONST16)
+      if (! TARGET_AUTO_LITPOOLS && ! TARGET_CONST16
+	  && ! (CONST_INT_P (src) && can_create_pseudo_p ()))
 	{
 	  src = force_const_mem (SImode, src);
 	  operands[1] = src;