[PATCH] i386: Relax extract location operand mode requirements [PR108516]

[PATCH] i386: Relax extract location operand mode requirements [PR108516]

[Uros Bizjak]

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Combine pass simplifies zero-extend of a zero-extract to:

Trying 16 -> 6:
   16: r86:QI#0=zero_extract(r87:HI,0x8,0x8)
      REG_DEAD r87:HI
    6: r84:SI=zero_extend(r86:QI)
      REG_DEAD r86:QI
Failed to match this instruction:
(set (reg:SI 84 [ s.e2 ])
    (zero_extract:SI (reg:HI 87)
        (const_int 8 [0x8])
        (const_int 8 [0x8])))

which fails instruction recognision.  The pattern is valid, since there
is no requirement on the mode of the location operand.

The patch relaxes location operand mode requirements of *extzv and *extv
insn patterns to allow all supported integer modes.  The patch also
adds support for a related sign-extend from zero-extracted operand.

2023-02-13  Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog:

    PR target/108516
    * config/i386/predicates.md (extr_register_operand):
    New special predicate.
    * config/i386/i386.md (*extv<mode>): Use extr_register_operand
    as operand 1 predicate.
    (*exzv<mode>): Ditto.
    (*extendqi<SWI24:mode>_ext_1): New insn pattern.

gcc/testsuite/ChangeLog:

    PR target/108516
    * gcc.target/i386/pr108516-1.c: New test.
    * gcc.target/i386/pr108516-2.c: Ditto.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Pushed to master.

Uros.

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diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index e62dd07ad8b..5a946beb1c6 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -3159,7 +3159,7 @@
 
 (define_insn "*extv<mode>"
   [(set (match_operand:SWI24 0 "register_operand" "=R")
-	(sign_extract:SWI24 (match_operand:SWI24 1 "register_operand" "Q")
+	(sign_extract:SWI24 (match_operand 1 "extr_register_operand" "Q")
 			    (const_int 8)
 			    (const_int 8)))]
   ""
@@ -3202,7 +3202,7 @@
 
 (define_insn "*extzv<mode>"
   [(set (match_operand:SWI248 0 "register_operand" "=R")
-	(zero_extract:SWI248 (match_operand:SWI248 1 "register_operand" "Q")
+	(zero_extract:SWI248 (match_operand 1 "extr_register_operand" "Q")
 			     (const_int 8)
 			     (const_int 8)))]
   ""
@@ -4777,6 +4777,19 @@
      (if_then_else (eq_attr "prefix_0f" "0")
 	(const_string "0")
 	(const_string "1")))])
+
+(define_insn "*extendqi<SWI24:mode>_ext_1"
+  [(set (match_operand:SWI24 0 "register_operand" "=R")
+	(sign_extend:SWI24
+	  (subreg:QI
+	    (zero_extract:SWI248
+	      (match_operand:SWI248 1 "register_operand" "Q")
+	      (const_int 8)
+	      (const_int 8)) 0)))]
+  ""
+  "movs{b<SWI24:imodesuffix>|x}\t{%h1, %0|%0, %h1}"
+   [(set_attr "type" "imovx")
+    (set_attr "mode" "<SWI24:MODE>")])
 \f
 ;; Conversions between float and double.
 
diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
index ec1785cde49..cca64f00a6a 100644
--- a/gcc/config/i386/predicates.md
+++ b/gcc/config/i386/predicates.md
@@ -92,6 +92,14 @@
   (and (match_code "reg")
        (match_test "MASK_REGNO_P (REGNO (op))")))
 
+;; Match a DI, SI or HImode register operand for extract op.
+(define_special_predicate "extr_register_operand"
+  (and (match_operand 0 "register_operand")
+       (ior (and (match_test "TARGET_64BIT")
+		 (match_test "GET_MODE (op) == DImode"))
+	    (match_test "GET_MODE (op) == SImode")
+	    (match_test "GET_MODE (op) == HImode"))))
+
 ;; Match a DI, SI, HI or QImode nonimmediate_operand.
 (define_special_predicate "int_nonimmediate_operand"
   (and (match_operand 0 "nonimmediate_operand")
diff --git a/gcc/testsuite/gcc.target/i386/pr108516-1.c b/gcc/testsuite/gcc.target/i386/pr108516-1.c
new file mode 100644
index 00000000000..d5344ef23e7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr108516-1.c
@@ -0,0 +1,19 @@
+/* PR target/108516 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -dp" } */
+/* { dg-additional-options "-mregparm=1" { target ia32 } } */
+
+struct S
+{
+  unsigned char e1;
+  unsigned char e2;
+  unsigned char e3;
+};
+
+unsigned int
+f2 (struct S s)
+{
+  return s.e2;
+}
+
+/* { dg-final { scan-assembler-not "\\*zero_extend" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr108516-2.c b/gcc/testsuite/gcc.target/i386/pr108516-2.c
new file mode 100644
index 00000000000..3e709e8c738
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr108516-2.c
@@ -0,0 +1,19 @@
+/* PR target/108516 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -dp" } */
+/* { dg-additional-options "-mregparm=1" { target ia32 } } */
+
+struct S
+{
+  signed char e1;
+  signed char e2;
+  signed char e3;
+};
+
+int
+f2 (struct S s)
+{
+  return s.e2;
+}
+
+/* { dg-final { scan-assembler-not "\\*extzv" } } */