[gcc12 backport] PR target/105930: Split *xordi3_doubleword after reload on x86.

[Roger Sayle]

This is a backport of the fix for PR target/105930 from mainline to the
gcc12 release branch.  This patch has been retested against the gcc12
branch on x86_64-pc-linux-gnu with make bootstrap and make -k check,
both with and without --target_board=unix{-m32} with no new failures.
Ok for the gcc12 branch?


2022-07-09  Roger Sayle  <ro...@nextmovesoftware.com>
            Uroš Bizjak  <ubiz...@gmail.com>

gcc/ChangeLog
        PR target/105930
        * config/i386/i386.md (*<any_or>di3_doubleword): Split after
        reload.  Use rtx_equal_p to avoid creating memory-to-memory moves,
        and emit NOTE_INSN_DELETED if operand[2] is zero (i.e. with -O0).


Thanks in advance,
Roger
--


diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 7c9560fc4..1c4781d 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -10400,22 +10400,25 @@
   "ix86_expand_binary_operator (<CODE>, <MODE>mode, operands); DONE;")
 
 (define_insn_and_split "*<code>di3_doubleword"
-  [(set (match_operand:DI 0 "nonimmediate_operand")
+  [(set (match_operand:DI 0 "nonimmediate_operand" "=ro,r")
        (any_or:DI
-        (match_operand:DI 1 "nonimmediate_operand")
-        (match_operand:DI 2 "x86_64_szext_general_operand")))
+        (match_operand:DI 1 "nonimmediate_operand" "0,0")
+        (match_operand:DI 2 "x86_64_szext_general_operand" "re,o")))
    (clobber (reg:CC FLAGS_REG))]
   "!TARGET_64BIT
-   && ix86_binary_operator_ok (<CODE>, DImode, operands)
-   && ix86_pre_reload_split ()"
+   && ix86_binary_operator_ok (<CODE>, DImode, operands)"
   "#"
-  "&& 1"
+  "&& reload_completed"
   [(const_int 0)]
 {
+  /* This insn may disappear completely when operands[2] == const0_rtx
+     and operands[0] == operands[1], which requires a NOTE_INSN_DELETED.  */
+  bool emit_insn_deleted_note_p = false;
+
   split_double_mode (DImode, &operands[0], 3, &operands[0], &operands[3]);
 
   if (operands[2] == const0_rtx)
-    emit_move_insn (operands[0], operands[1]);
+    emit_insn_deleted_note_p = true;
   else if (operands[2] == constm1_rtx)
     {
       if (<CODE> == IOR)
@@ -10427,7 +10430,10 @@
     ix86_expand_binary_operator (<CODE>, SImode, &operands[0]);
 
   if (operands[5] == const0_rtx)
-    emit_move_insn (operands[3], operands[4]);
+    {
+      if (emit_insn_deleted_note_p)
+       emit_note (NOTE_INSN_DELETED);
+    }
   else if (operands[5] == constm1_rtx)
     {
       if (<CODE> == IOR)