[gcc(refs/vendors/ibm/heads/perf)] Fix PR94185: Do not reuse insn alternative after changing memory subreg.

[Jiu Fu Guo]

https://gcc.gnu.org/g:bae7b38cf8a21e068ad5c0bab089dedb78af3346

commit bae7b38cf8a21e068ad5c0bab089dedb78af3346
Author: Vladimir N. Makarov <vmakarov@redhat.com>
Date:   Mon Mar 16 16:42:19 2020 -0400

    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.

Diff:
---
 gcc/ChangeLog                           |  6 ++++++
 gcc/lra-spills.c                        | 12 +++++++++++-
 gcc/testsuite/ChangeLog                 |  5 +++++
 gcc/testsuite/g++.target/i386/pr94185.C | 33 +++++++++++++++++++++++++++++++++
 4 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 03ac0d439da..25a27f8070d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+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>
 
diff --git a/gcc/lra-spills.c b/gcc/lra-spills.c
index 01256e711bc..a4b955ac3d4 100644
--- a/gcc/lra-spills.c
+++ b/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
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c3d6eccea0c..3b277cecac3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+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
diff --git a/gcc/testsuite/g++.target/i386/pr94185.C b/gcc/testsuite/g++.target/i386/pr94185.C
new file mode 100644
index 00000000000..587b7bac6db
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr94185.C
@@ -0,0 +1,33 @@
+/* { 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);
+}