The following committed patch solves
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92303
The patch was successfully bootstrapped and tested on x86-64.
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d63b83194d5..4ea81e6c404 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-13 Vladimir Makarov <vmaka...@redhat.com>
+
+ PR rtl-optimization/92303
+ * lra-spills.c (remove_pseudos): Try to simplify memory subreg.
+
2020-03-13 Segher Boessenkool <seg...@kernel.crashing.org>
PR rtl-optimization/94148
diff --git a/gcc/lra-spills.c b/gcc/lra-spills.c
index 0022611785c..01256e711bc 100644
--- a/gcc/lra-spills.c
+++ b/gcc/lra-spills.c
@@ -421,7 +421,16 @@ remove_pseudos (rtx *loc, rtx_insn *insn)
if (*loc == NULL_RTX)
return res;
code = GET_CODE (*loc);
- if (code == REG && (i = REGNO (*loc)) >= FIRST_PSEUDO_REGISTER
+ if (code == SUBREG && REG_P (SUBREG_REG (*loc)))
+ {
+ /* Try to remove memory subregs to simplify LRA job
+ 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);
+ return res;
+ }
+ else if (code == REG && (i = REGNO (*loc)) >= FIRST_PSEUDO_REGISTER
&& lra_get_regno_hard_regno (i) < 0
/* We do not want to assign memory for former scratches because
it might result in an address reload for some targets. In
