S/390: Fix a problem with the bswap vector pattern

arch13 introduced instructions to perform vector element-wise byte
swaps on the way from or to memory.  For a byte swap between vector
registers the vector permute instruction is required which needs a
permute pattern to be loaded into a vector register first.

With the current implementation there is a potential problem when the
decision for the reg-reg variant is made very late.  This patch is
supposed to fix that.

With the patch the required permute pattern is generated already in
the expander and attached to the bswap pattern as USE operand.  The
predicate in the insn_and_split pattern accepts it although the
permute constant as such is not a valid constant.  For the reg-reg
variant only the vector register constraint is used for the permute
constant forcing LRA to a) push the constant into literal pool and b)
load the literal pool constant into a vector register.

gcc/ChangeLog:

2019-04-12  Andreas Krebbel  <krebbel@linux.ibm.com>

	* config/s390/predicates.md (permute_pattern_operand): New
	predicate.
	* config/s390/vector.md ("*vec_splats_bswap_vec<mode>"): Add USE
	operand for the permute pattern.
	("*vec_perm<mode>"): New insn definition.
	("bswap<mode>"): Generate the permute pattern operand in the
	expander and perform the operand reloads for pre arch13 level
	already.
	("*bswap<mode>_emu"): Rename to ...
	("*bswap<mode>"): ... this. And make the splitter vxe2 only.
	* config/s390/vx-builtins.md ("*vec_insert_and_zero_bswap<mode>"):
	Add the USE operand for the permute pattern.
	("*vec_set_bswap_vec<mode>"): Likewise.

From-SVN: r270306

4 files changed, 105 insertions, 46 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e728a9a1692..fd3e7c631b4 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,19 @@
+2019-04-12  Andreas Krebbel  <krebbel@linux.ibm.com>
+
+	* config/s390/predicates.md (permute_pattern_operand): New
+	predicate.
+	* config/s390/vector.md ("*vec_splats_bswap_vec<mode>"): Add USE
+	operand for the permute pattern.
+	("*vec_perm<mode>"): New insn definition.
+	("bswap<mode>"): Generate the permute pattern operand in the
+	expander and perform the operand reloads for pre arch13 level
+	already.
+	("*bswap<mode>_emu"): Rename to ...
+	("*bswap<mode>"): ... this. And make the splitter vxe2 only.
+	* config/s390/vx-builtins.md ("*vec_insert_and_zero_bswap<mode>"):
+	Add the USE operand for the permute pattern.
+	("*vec_set_bswap_vec<mode>"): Likewise.
+
 2019-04-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/89946
diff --git a/gcc/config/s390/predicates.md b/gcc/config/s390/predicates.md
index 9a3d99e7897..92c602e4add 100644
--- a/gcc/config/s390/predicates.md
+++ b/gcc/config/s390/predicates.md
@@ -46,6 +46,16 @@
   (and (match_code "symbol_ref, label_ref, const, const_int, const_wide_int, const_double, const_vector")
        (match_test "CONSTANT_P (op)")))
 
+; An operand used as vector permutation pattern
+
+; This in particular accepts constants which would otherwise be
+; rejected.  These constants require special post reload handling
+
+(define_special_predicate "permute_pattern_operand"
+  (and (match_code "const_vector,mem,reg,subreg")
+       (match_test "GET_MODE (op) == V16QImode")
+       (match_test "!MEM_P (op) || s390_mem_constraint (\"R\", op)")))
+
 ;; Return true if OP is a valid S-type operand.
 
 (define_predicate "s_operand"
diff --git a/gcc/config/s390/vector.md b/gcc/config/s390/vector.md
index 8f02af4d20f..a2c10124577 100644
--- a/gcc/config/s390/vector.md
+++ b/gcc/config/s390/vector.md
@@ -551,9 +551,10 @@
 
 ; vlbrreph, vlbrrepf, vlbrrepg
 (define_insn "*vec_splats_bswap_vec<mode>"
-  [(set (match_operand:V_HW_HSD                           0 "register_operand" "=v")
+  [(set (match_operand:V_HW_HSD                           0 "register_operand"        "=v")
 	(bswap:V_HW_HSD
-	 (vec_duplicate:V_HW_HSD (match_operand:<non_vec> 1 "memory_operand"    "R"))))]
+	 (vec_duplicate:V_HW_HSD (match_operand:<non_vec> 1 "memory_operand"           "R"))))
+   (use (match_operand:V16QI                              2 "permute_pattern_operand"  "X"))]
   "TARGET_VXE2"
   "vlbrrep<bhfgq>\t%v0,%1"
   [(set_attr "op_type" "VRX")])
@@ -655,6 +656,17 @@
   "vperm\t%v0,%v1,%v2,%v3"
   [(set_attr "op_type" "VRR")])
 
+(define_insn "*vec_perm<mode>"
+  [(set (match_operand:VT_HW                                            0 "register_operand" "=v")
+	(subreg:VT_HW (unspec:V16QI [(subreg:V16QI (match_operand:VT_HW 1 "register_operand"  "v") 0)
+				     (subreg:V16QI (match_operand:VT_HW 2 "register_operand"  "v") 0)
+				     (match_operand:V16QI               3 "register_operand"  "v")]
+				    UNSPEC_VEC_PERM) 0))]
+  "TARGET_VX"
+  "vperm\t%v0,%v1,%v2,%v3"
+  [(set_attr "op_type" "VRR")])
+
+
 ; vec_perm_const for V2DI using vpdi?
 
 ;;
@@ -2073,35 +2085,11 @@
 ; FIXME: The bswap rtl standard name currently does not appear to be
 ; used for vector modes.
 (define_expand "bswap<mode>"
-  [(set (match_operand:VT_HW_HSDT                   0 "nonimmediate_operand" "")
-	(bswap:VT_HW_HSDT (match_operand:VT_HW_HSDT 1 "nonimmediate_operand" "")))]
-  "TARGET_VX")
-
-; vlbrh, vlbrf, vlbrg, vlbrq, vstbrh, vstbrf, vstbrg, vstbrq
-(define_insn "*bswap<mode>"
-  [(set (match_operand:VT_HW_HSDT                   0 "nonimmediate_operand" "=v,v,R")
-	(bswap:VT_HW_HSDT (match_operand:VT_HW_HSDT 1 "nonimmediate_operand"  "v,R,v")))]
-  "TARGET_VXE2"
-  "@
-   #
-   vlbr<bhfgq>\t%v0,%v1
-   vstbr<bhfgq>\t%v1,%v0"
-  [(set_attr "op_type" "*,VRX,VRX")])
-
-(define_insn_and_split "*bswap<mode>_emu"
-  [(set (match_operand:VT_HW_HSDT                   0 "nonimmediate_operand" "=vR")
-	(bswap:VT_HW_HSDT (match_operand:VT_HW_HSDT 1 "nonimmediate_operand" "vR")))]
-  "TARGET_VX && can_create_pseudo_p ()"
-  "#"
-  "&& ((!memory_operand (operands[1], <MODE>mode)
-        && !memory_operand (operands[0], <MODE>mode))
-        || !TARGET_VXE2)"
-  [(set (match_dup 3)
-	(unspec:V16QI [(match_dup 4)
-		       (match_dup 4)
-		       (match_dup 2)]
-		      UNSPEC_VEC_PERM))
-   (set (match_dup 0) (subreg:VT_HW_HSDT (match_dup 3) 0))]
+  [(parallel
+    [(set (match_operand:VT_HW_HSDT                   0 "nonimmediate_operand" "")
+	  (bswap:VT_HW_HSDT (match_operand:VT_HW_HSDT 1 "nonimmediate_operand" "")))
+     (use (match_dup 2))])]
+  "TARGET_VX"
 {
   static char p[4][16] =
     { { 1,  0,  3,  2,  5,  4,  7, 6, 9,  8,  11, 10, 13, 12, 15, 14 },   /* H */
@@ -2109,7 +2097,7 @@
       { 7,  6,  5,  4,  3,  2,  1, 0, 15, 14, 13, 12, 11, 10, 9,  8  },   /* D */
       { 15, 14, 13, 12, 11, 10, 9, 8, 7,  6,  5,  4,  3,  2,  1,  0  } }; /* T */
   char *perm;
-  rtx perm_rtx[16], constv;
+  rtx perm_rtx[16];
 
   switch (GET_MODE_SIZE (GET_MODE_INNER (<MODE>mode)))
     {
@@ -2122,14 +2110,57 @@
   for (int i = 0; i < 16; i++)
     perm_rtx[i] = GEN_INT (perm[i]);
 
-  operands[1] = force_reg (<MODE>mode, operands[1]);
-  operands[2] = gen_reg_rtx (V16QImode);
-  operands[3] = gen_reg_rtx (V16QImode);
-  operands[4] = simplify_gen_subreg (V16QImode, operands[1], <MODE>mode, 0);
-  constv = force_const_mem (V16QImode, gen_rtx_CONST_VECTOR (V16QImode, gen_rtvec_v (16, perm_rtx)));
-  emit_move_insn (operands[2], constv);
+  operands[2] = gen_rtx_CONST_VECTOR (V16QImode, gen_rtvec_v (16, perm_rtx));
+
+  /* Without vxe2 we do not have byte swap instructions dealing
+     directly with memory operands.  So instead of waiting until
+     reload to fix that up switch over to vector permute right
+     now.  */
+  if (!TARGET_VXE2)
+    {
+      rtx in = force_reg (V16QImode, simplify_gen_subreg (V16QImode, operands[1], <MODE>mode, 0));
+      rtx permute = force_reg (V16QImode, force_const_mem (V16QImode, operands[2]));
+      rtx out = gen_reg_rtx (V16QImode);
+
+      emit_insn (gen_vec_permv16qi (out, in, in, permute));
+      emit_move_insn (operands[0], simplify_gen_subreg (<MODE>mode, out, V16QImode, 0));
+      DONE;
+    }
 })
 
+; Switching late to the reg-reg variant requires the vector permute
+; pattern to be pushed into literal pool and allocating a vector
+; register to load it into.  We rely on both being provided by LRA
+; when fixing up the v constraint for operand 2.
+
+; permute_pattern_operand: general_operand would reject the permute
+; pattern constants since these are not accepted by
+; s390_legimitate_constant_p
+
+; ^R: Prevent these alternatives from being chosen if it would require
+; pushing the operand into memory first
+
+; vlbrh, vlbrf, vlbrg, vlbrq, vstbrh, vstbrf, vstbrg, vstbrq
+(define_insn_and_split "*bswap<mode>"
+  [(set (match_operand:VT_HW_HSDT                   0 "nonimmediate_operand"    "=v, v,^R")
+	(bswap:VT_HW_HSDT (match_operand:VT_HW_HSDT 1 "nonimmediate_operand"     "v,^R, v")))
+   (use (match_operand:V16QI                        2 "permute_pattern_operand"  "v, X, X"))]
+  "TARGET_VXE2"
+  "@
+   #
+   vlbr<bhfgq>\t%v0,%v1
+   vstbr<bhfgq>\t%v1,%v0"
+  "&& reload_completed
+   && !memory_operand (operands[0], <MODE>mode)
+   && !memory_operand (operands[1], <MODE>mode)"
+  [(set (match_dup 0)
+	(subreg:VT_HW_HSDT
+	 (unspec:V16QI [(subreg:V16QI (match_dup 1) 0)
+			(subreg:V16QI (match_dup 1) 0)
+			(match_dup 2)]
+		       UNSPEC_VEC_PERM) 0))]
+  ""
+  [(set_attr "op_type"      "*,VRX,VRX")])
 
 ; reduc_smin
 ; reduc_smax
diff --git a/gcc/config/s390/vx-builtins.md b/gcc/config/s390/vx-builtins.md
index 22189ff2414..3020bc94d3e 100644
--- a/gcc/config/s390/vx-builtins.md
+++ b/gcc/config/s390/vx-builtins.md
@@ -183,10 +183,11 @@
 ; vec_revb (vec_insert_and_zero(x))             bswap-and-replicate-1.c
 ; vllebrzh, vllebrzf, vllebrzg
 (define_insn "*vec_insert_and_zero_bswap<mode>"
-  [(set (match_operand:V_HW_HSD                    0 "register_operand" "=v")
+  [(set (match_operand:V_HW_HSD                    0 "register_operand"       "=v")
 	(bswap:V_HW_HSD (unspec:V_HW_HSD
-			 [(match_operand:<non_vec> 1 "memory_operand"    "R")]
-			 UNSPEC_VEC_INSERT_AND_ZERO)))]
+			 [(match_operand:<non_vec> 1 "memory_operand"          "R")]
+			 UNSPEC_VEC_INSERT_AND_ZERO)))
+   (use (match_operand:V16QI                       2 "permute_pattern_operand" "X"))]
   "TARGET_VXE2"
   "vllebrz<bhfgq>\t%v0,%1"
   [(set_attr "op_type" "VRX")])
@@ -2243,12 +2244,13 @@
 ; vec_revb (vec_insert (*a, vec_revb (b), 1))      set-element-bswap-1.c
 ; vlebrh, vlebrf, vlebrg
 (define_insn "*vec_set_bswap_vec<mode>"
-  [(set (match_operand:V_HW_HSD                                     0 "register_operand" "=v")
+  [(set (match_operand:V_HW_HSD                                     0 "register_operand"       "=v")
 	(bswap:V_HW_HSD
-	 (unspec:V_HW_HSD [(match_operand:<non_vec>                 1 "memory_operand"    "R")
-		           (match_operand:SI                        2 "const_int_operand" "C")
-			   (bswap:V_HW_HSD (match_operand:V_HW_HSD  3 "register_operand"  "0"))]
-			  UNSPEC_VEC_SET)))]
+	 (unspec:V_HW_HSD [(match_operand:<non_vec>                 1 "memory_operand"          "R")
+		           (match_operand:SI                        2 "const_int_operand"       "C")
+			   (bswap:V_HW_HSD (match_operand:V_HW_HSD  3 "register_operand"        "0"))]
+			  UNSPEC_VEC_SET)))
+   (use (match_operand:V16QI                                        4 "permute_pattern_operand" "X"))]
   "TARGET_VXE2 && UINTVAL (operands[2]) < GET_MODE_NUNITS (<V_HW_HSD:MODE>mode)"
   "vlebr<bhfgq>\t%v0,%1,%2"
   [(set_attr "op_type" "VRX")])