From 22b25535b8b2f9961e4772b1cc7cce5dc2f60719 Mon Sep 17 00:00:00 2001
From: Andreas Krebbel <krebbel@linux.ibm.com>
Date: Wed, 22 Sep 2021 09:32:21 +0200
Subject: [PATCH] IBM Z: Fix PR102222

Avoid emitting a strict low part move if the insv target actually
affects the whole target reg.

gcc/ChangeLog:

	PR target/102222
	* config/s390/s390.c (s390_expand_insv): Emit a normal move if it
	is actually a full copy of the source operand into the target.
	Don't emit a strict low part move if source and target mode match.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/pr102222.c: New test.

(cherry picked from commit a9b3c451be58f0fe660154323ace7ba72a4211ec)
---
 gcc/config/s390/s390.c                   | 10 ++++++++++
 gcc/testsuite/gcc.target/s390/pr102222.c | 16 ++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/s390/pr102222.c

diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index 6bbeb640e1fc..c5d4c439bcc7 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -6411,6 +6411,15 @@ s390_expand_insv (rtx dest, rtx op1, rtx op2, rtx src)
   if (bitsize + bitpos > GET_MODE_BITSIZE (mode))
     return false;
 
+  /* Just a move.  */
+  if (bitpos == 0
+      && bitsize == GET_MODE_BITSIZE (GET_MODE (src))
+      && mode == GET_MODE (src))
+    {
+      emit_move_insn (dest, src);
+      return true;
+    }
+
   /* Generate INSERT IMMEDIATE (IILL et al).  */
   /* (set (ze (reg)) (const_int)).  */
   if (TARGET_ZARCH
@@ -6507,6 +6516,7 @@ s390_expand_insv (rtx dest, rtx op1, rtx op2, rtx src)
       && (bitpos & 32) == ((bitpos + bitsize - 1) & 32)
       && MEM_P (src)
       && (mode == DImode || mode == SImode)
+      && mode != smode
       && register_operand (dest, mode))
     {
       /* Emit a strict_low_part pattern if possible.  */
diff --git a/gcc/testsuite/gcc.target/s390/pr102222.c b/gcc/testsuite/gcc.target/s390/pr102222.c
new file mode 100644
index 000000000000..47d075e47fcc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/pr102222.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -m31 -mesa" } */
+
+struct squashfs_reg_inode_header_1 read_inode_inode;
+
+int read_inode_val;
+
+struct squashfs_reg_inode_header_1
+{
+  int file_size:32;
+} __attribute__((packed)) read_inode ();
+
+void foo (void)
+{
+  read_inode_inode.file_size = read_inode_val;
+}
-- 
2.47.2