Fix PR94185: Do not reuse insn alternative after changing memory subreg.

2020-03-16  Vladimir Makarov  <vmakarov@redhat.com>

	PR target/94185
	* lra-spills.c (remove_pseudos): Do not reuse insn alternative
	after changing memory subreg.

2020-03-16  Vladimir Makarov  <vmakarov@redhat.com>

	PR target/94185
	* g++.target/i386/pr94185.C: New test.

gcc/ChangeLog

+2020-03-16  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR target/94185
+	* lra-spills.c (remove_pseudos): Do not reuse insn alternative
+	after changing memory subreg.
+
 2020-03-16  Andre Vieira  <andre.simoesdiasvieira@arm.com>
             Srinath Parvathaneni  <srinath.parvathaneni@arm.com>
 

gcc/lra-spills.c

@@ -427,7 +427,17 @@ remove_pseudos (rtx *loc, rtx_insn *insn)
          and avoid LRA cycling in case of subreg memory reload.  */
       res = remove_pseudos (&SUBREG_REG (*loc), insn);
       if (GET_CODE (SUBREG_REG (*loc)) == MEM)
-	alter_subreg (loc, false);
+	{
+	  alter_subreg (loc, false);
+	  if (GET_CODE (*loc) == MEM)
+	    {
+	      lra_get_insn_recog_data (insn)->used_insn_alternative = -1;
+	      if (lra_dump_file != NULL)
+		fprintf (lra_dump_file,
+			 "Memory subreg was simplified in in insn #%u\n",
+			 INSN_UID (insn));
+	    }
+	}
       return res;
     }
   else if (code == REG && (i = REGNO (*loc)) >= FIRST_PSEUDO_REGISTER

gcc/testsuite/ChangeLog

+2020-03-16  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR target/94185
+	* g++.target/i386/pr94185.C: New test.
+
 2020-03-16  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* gcc.target/aarch64/sve/acle/general-c/sizeless-1.c: Add a test

gcc/testsuite/g++.target/i386/pr94185.C

+/* { dg-do compile } */
+/* { dg-options "-O2 -fPIE -fstack-protector-strong" } */
+
+struct a {
+  int b;
+  int c();
+  a() : b(c()) {}
+  ~a();
+  char *e();
+};
+struct f {
+  void g(int);
+};
+struct ar {
+  int au[256];
+  f h(int);
+} bb;
+a i();
+a j(int);
+long k(int, ar);
+int d;
+void l(char *, ar m, long n) {
+  switch (m.au[d])
+  case 0:
+    n &= 4294967295;
+  bb.h(0).g(n);
+}
+void o() {
+  ar bd;
+  a bh, bi, attrname = j(0) = i();
+  int be = k(0, bd);
+  l(attrname.e(), bd, be);
+}