S/390: Hotpatch: Remove special handling of nested functions.

gcc/
2015-03-31  Dominik Vogt  <vogt@linux.vnet.ibm.com>

	    * config/s390/s390.c (s390_function_num_hotpatch_hw): Allow hotpatching
	    nested functions.
	    (s390_reorg): Adapt to new signature of s390_function_num_hotpatch_hw.
	    (s390_asm_output_function_label): Adapt to new signature of
	    s390_function_num_hotpatch_hw
	    Optimise the code generating assembler output.
	    Add comments to assembler file.

gcc/testsuite
2015-03-31  Dominik Vogt  <vogt@linux.vnet.ibm.com>

	    * gcc.target/s390/hotpatch-25.c: New test.
	    * gcc.target/s390/hotpatch-1.c: Update test.
	    * gcc.target/s390/hotpatch-10.c: Update test.
	    * gcc.target/s390/hotpatch-11.c: Update test.
	    * gcc.target/s390/hotpatch-12.c: Update test.
	    * gcc.target/s390/hotpatch-13.c: Update test.
	    * gcc.target/s390/hotpatch-14.c: Update test.
	    * gcc.target/s390/hotpatch-15.c: Update test.
	    * gcc.target/s390/hotpatch-16.c: Update test.
	    * gcc.target/s390/hotpatch-17.c: Update test.
	    * gcc.target/s390/hotpatch-18.c: Update test.
	    * gcc.target/s390/hotpatch-19.c: Update test.
	    * gcc.target/s390/hotpatch-2.c: Update test.
	    * gcc.target/s390/hotpatch-21.c: Update test.
	    * gcc.target/s390/hotpatch-22.c: Update test.
	    * gcc.target/s390/hotpatch-23.c: Update test.
	    * gcc.target/s390/hotpatch-24.c: Update test.
	    * gcc.target/s390/hotpatch-3.c: Update test.
	    * gcc.target/s390/hotpatch-4.c: Update test.
	    * gcc.target/s390/hotpatch-5.c: Update test.
	    * gcc.target/s390/hotpatch-6.c: Update test.
	    * gcc.target/s390/hotpatch-7.c: Update test.
	    * gcc.target/s390/hotpatch-8.c: Update test.
	    * gcc.target/s390/hotpatch-9.c: Update test.
	    * gcc.target/s390/hotpatch-compile-16.c: Update test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_8-branch@221792 138bc75d-0d04-0410-961f-82ee72b054a4

28 files changed, 154 insertions, 44 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 847266ff864..56050af696d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,15 @@
 2015-03-31  Dominik Vogt  <vogt@linux.vnet.ibm.com>
 
+	* config/s390/s390.c (s390_function_num_hotpatch_hw): Allow hotpatching
+	nested functions.
+	(s390_reorg): Adapt to new signature of s390_function_num_hotpatch_hw.
+	(s390_asm_output_function_label): Adapt to new signature of
+	s390_function_num_hotpatch_hw
+	Optimise the code generating assembler output.
+	Add comments to assembler file.
+
+2015-03-31  Dominik Vogt  <vogt@linux.vnet.ibm.com>
+
 	* config/s390/s390.c (s390_function_num_hotpatch_hw): Remove special
 	cases for not hotpatching main () and artificial functions.
 
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index fc884e55146..57cd8bdbca9 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -5432,51 +5432,35 @@ get_some_local_dynamic_name (void)
   gcc_unreachable ();
 }
 
-/* Returns false if the function should not be made hotpatchable.
-   Otherwise it assigns the number of NOP halfwords to be emitted
-   before and after the function label to hw_before and hw_after.
-   Both must not be NULL.  */
+/* Assigns the number of NOP halfwords to be emitted before and after the
+   function label to *HW_BEFORE and *HW_AFTER.  Both pointers must not be NULL.
+   If hotpatching is disabled for the function, the values are set to zero.
+*/
 
-static bool
+static void
 s390_function_num_hotpatch_hw (tree decl,
 			       int *hw_before,
 			       int *hw_after)
 {
   tree attr;
 
-  *hw_before = 0;
-  *hw_after = 0;
-
   attr = lookup_attribute ("hotpatch", DECL_ATTRIBUTES (decl));
 
-  /* Handle the arguments of the hotpatch attribute.  The values
-     specified via attribute might override the cmdline argument
-     values.  */
   if (attr)
     {
       tree args = TREE_VALUE (attr);
 
+      /* If the hotpatch attribute is present, its values are used even if the
+	 -mhotpatch cmdline option is used.  */
       *hw_before = TREE_INT_CST_LOW (TREE_VALUE (args));
       *hw_after = TREE_INT_CST_LOW (TREE_VALUE (TREE_CHAIN (args)));
     }
   else
     {
-      /* Use the values specified by the cmdline arguments.  */
+      /* Values specified by the -mhotpatch cmdline option.  */
       *hw_before = s390_hotpatch_hw_before_label;
       *hw_after = s390_hotpatch_hw_after_label;
     }
-
-  if (*hw_before == 0 && *hw_after == 0)
-    return false;
-
-  if (decl_function_context (decl) != NULL_TREE)
-    {
-      warning_at (DECL_SOURCE_LOCATION (decl), OPT_mhotpatch_,
-		  "hotpatching is not compatible with nested functions");
-      return false;
-    }
-
-  return true;
 }
 
 
@@ -5487,36 +5471,45 @@ s390_asm_output_function_label (FILE *asm_out_file, const char *fname,
 				tree decl)
 {
   int hw_before, hw_after;
-  bool hotpatch_p = (decl
-		     ? s390_function_num_hotpatch_hw (decl,
-						      &hw_before, &hw_after)
-		     : false);
 
-  if (hotpatch_p)
+  s390_function_num_hotpatch_hw (decl, &hw_before, &hw_after);
+  if (hw_before > 0)
     {
       unsigned int function_alignment;
       int i;
 
-      /* Add a trampoline code area before the function label and initialize it
-	 with two-byte nop instructions.  This area can be overwritten with code
+      /* Add trampoline code area before the function label and initialize it
+	 with two-byte NOP instructions.  This area can be overwritten with code
 	 that jumps to a patched version of the function.  */
-      for (i = 0; i < hw_before; i++)
-	asm_fprintf (asm_out_file, "\tnopr\t%%r7\n");
+      asm_fprintf (asm_out_file, "\tnopr\t%%r7"
+		   "\t# pre-label NOPs for hotpatch (%d halfwords)\n",
+		   hw_before);
+      for (i = 1; i < hw_before; i++)
+	fputs ("\tnopr\t%r7\n", asm_out_file);
+
       /* Note:  The function label must be aligned so that (a) the bytes of the
-	 following nop do not cross a cacheline boundary, and (b) a jump address
+	 following NOP do not cross a cacheline boundary, and (b) a jump address
 	 (eight bytes for 64 bit targets, 4 bytes for 32 bit targets) can be
 	 stored directly before the label without crossing a cacheline
 	 boundary.  All this is necessary to make sure the trampoline code can
-	 be changed atomically.  */
+	 be changed atomically.
+	 This alignment is done automatically using the FOUNCTION_BOUNDARY
+	 macro, but if there are NOPs before the function label, the alignment
+	 is placed before them.  So it is necessary to duplicate the alignment
+	 after the NOPs.  */
       function_alignment = MAX (8, DECL_ALIGN (decl) / BITS_PER_UNIT);
       if (! DECL_USER_ALIGN (decl))
 	function_alignment = MAX (function_alignment,
 				  (unsigned int) align_functions);
+      fputs ("\t# alignment for hotpatch\n", asm_out_file);
       ASM_OUTPUT_ALIGN (asm_out_file, floor_log2 (function_alignment));
     }
 
   ASM_OUTPUT_LABEL (asm_out_file, fname);
-
+  if (hw_after > 0)
+    asm_fprintf (asm_out_file,
+		 "\t# post-label NOPs for hotpatch (%d halfwords)\n",
+		 hw_after);
 }
 
 /* Output machine-dependent UNSPECs occurring in address constant X
@@ -11268,7 +11261,7 @@ s390_reorg (void)
     {
       rtx insn;
 
-      /* Inject nops for hotpatching. */
+      /* Insert NOPs for hotpatching. */
       for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
 	{
 	  if (NOTE_P (insn) && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index dd7039bdb4a..cf8b0bd47d0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,33 @@
 2015-03-31  Dominik Vogt  <vogt@linux.vnet.ibm.com>
 
+	* gcc.target/s390/hotpatch-25.c: New test.
+	* gcc.target/s390/hotpatch-1.c: Update test.
+	* gcc.target/s390/hotpatch-10.c: Update test.
+	* gcc.target/s390/hotpatch-11.c: Update test.
+	* gcc.target/s390/hotpatch-12.c: Update test.
+	* gcc.target/s390/hotpatch-13.c: Update test.
+	* gcc.target/s390/hotpatch-14.c: Update test.
+	* gcc.target/s390/hotpatch-15.c: Update test.
+	* gcc.target/s390/hotpatch-16.c: Update test.
+	* gcc.target/s390/hotpatch-17.c: Update test.
+	* gcc.target/s390/hotpatch-18.c: Update test.
+	* gcc.target/s390/hotpatch-19.c: Update test.
+	* gcc.target/s390/hotpatch-2.c: Update test.
+	* gcc.target/s390/hotpatch-21.c: Update test.
+	* gcc.target/s390/hotpatch-22.c: Update test.
+	* gcc.target/s390/hotpatch-23.c: Update test.
+	* gcc.target/s390/hotpatch-24.c: Update test.
+	* gcc.target/s390/hotpatch-3.c: Update test.
+	* gcc.target/s390/hotpatch-4.c: Update test.
+	* gcc.target/s390/hotpatch-5.c: Update test.
+	* gcc.target/s390/hotpatch-6.c: Update test.
+	* gcc.target/s390/hotpatch-7.c: Update test.
+	* gcc.target/s390/hotpatch-8.c: Update test.
+	* gcc.target/s390/hotpatch-9.c: Update test.
+	* gcc.target/s390/hotpatch-compile-16.c: Update test.
+
+2015-03-31  Dominik Vogt  <vogt@linux.vnet.ibm.com>
+
 	* gcc.target/s390/hotpatch-compile-16.c: Remove include of stdio.h.
 
 2015-03-26  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-1.c b/gcc/testsuite/gcc.target/s390/hotpatch-1.c
index 4e29817991e..b14fa9010a8 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-1.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-1.c
@@ -11,6 +11,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-10.c b/gcc/testsuite/gcc.target/s390/hotpatch-10.c
index 352c9d500d7..a990c4cad6e 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-10.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-10.c
@@ -11,6 +11,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-11.c b/gcc/testsuite/gcc.target/s390/hotpatch-11.c
index beb8738c653..6f8a52b26d3 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-11.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-11.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler "pre-label.*(1 halfwords)" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-12.c b/gcc/testsuite/gcc.target/s390/hotpatch-12.c
index d109478b04f..b73ca90fd3d 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-12.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-12.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler "pre-label.*(999 halfwords)" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 999 } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-13.c b/gcc/testsuite/gcc.target/s390/hotpatch-13.c
index 9ac9f842d63..150667a1c66 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-13.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-13.c
@@ -12,6 +12,10 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler "pre-label.*(1 halfwords)" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler "alignment for hotpatch" } } */
+/* { dg-final { scan-assembler-times "\.align\t8" 2 } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-14.c b/gcc/testsuite/gcc.target/s390/hotpatch-14.c
index 209e4ac5e47..c5f118c1cc6 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-14.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-14.c
@@ -12,6 +12,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(2 halfwords)" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-15.c b/gcc/testsuite/gcc.target/s390/hotpatch-15.c
index 109034ef019..ef0fb746227 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-15.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-15.c
@@ -12,6 +12,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler "pre-label.*(1 halfwords)" } } */
+/* { dg-final { scan-assembler "post-label.*(2 halfwords)" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-16.c b/gcc/testsuite/gcc.target/s390/hotpatch-16.c
index b01c1c32254..a34bf95c3cb 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-16.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-16.c
@@ -12,6 +12,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler "pre-label.*(1 halfwords)" } } */
+/* { dg-final { scan-assembler "post-label.*(2 halfwords)" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-17.c b/gcc/testsuite/gcc.target/s390/hotpatch-17.c
index ce0b950f8d3..66ac725d16a 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-17.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-17.c
@@ -12,6 +12,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-18.c b/gcc/testsuite/gcc.target/s390/hotpatch-18.c
index 9a24d5e6a77..8b076a4e175 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-18.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-18.c
@@ -11,6 +11,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler-not "post-label NOPs" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-19.c b/gcc/testsuite/gcc.target/s390/hotpatch-19.c
index 3586da29a89..6993c7e855c 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-19.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-19.c
@@ -18,6 +18,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler "pre-label.*(1 halfwords)" } } */
+/* { dg-final { scan-assembler "post-label.*(2 halfwords)" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-2.c b/gcc/testsuite/gcc.target/s390/hotpatch-2.c
index 18be5aa2383..67189f8a28b 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-2.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-2.c
@@ -11,7 +11,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(1 halfwords)" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
-/* { dg-final { scan-assembler-times "\.align\t8" 2 } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-21.c b/gcc/testsuite/gcc.target/s390/hotpatch-21.c
index d72dee318cf..e9099900855 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-21.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-21.c
@@ -11,4 +11,4 @@ void __attribute__ ((aligned(512))) hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
-/* { dg-final { scan-assembler-times "\.align\t512" 2 } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-22.c b/gcc/testsuite/gcc.target/s390/hotpatch-22.c
index 65074661023..d89d7790426 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-22.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-22.c
@@ -11,4 +11,4 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
-/* { dg-final { scan-assembler-times "\.align\t1024" 2 } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-23.c b/gcc/testsuite/gcc.target/s390/hotpatch-23.c
index 7dce5b8b0fa..1e05d123c22 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-23.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-23.c
@@ -11,4 +11,4 @@ void __attribute__ ((aligned(2048))) hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
-/* { dg-final { scan-assembler-times "\.align\t2048" 2 } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-24.c b/gcc/testsuite/gcc.target/s390/hotpatch-24.c
index 4d6815cb516..fc6427479d8 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-24.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-24.c
@@ -11,4 +11,4 @@ void __attribute__ ((aligned(4096))) hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
-/* { dg-final { scan-assembler-times "\.align\t4096" 2 } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-25.c b/gcc/testsuite/gcc.target/s390/hotpatch-25.c
new file mode 100644
index 00000000000..e9257e3744e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-25.c
@@ -0,0 +1,33 @@
+/* Functional tests for the function hotpatching feature.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O3 -mzarch" } */
+
+typedef long (*fn_t)(void);
+
+__attribute__ ((hotpatch(1,2)))
+fn_t outer(void)
+{
+  __attribute__ ((hotpatch(4,8)))
+  long nested1(void)
+  {
+    __attribute__ ((hotpatch(16,32)))
+    long nested2(void)
+    {
+      return 2;
+    }
+    return (long)(void *)nested2;
+  }
+
+  return nested1;
+}
+
+/* { dg-final { scan-assembler "pre-label.*(1 halfwords)" } } */
+/* { dg-final { scan-assembler "pre-label.*(4 halfwords)" } } */
+/* { dg-final { scan-assembler "pre-label.*(16 halfwords)" } } */
+/* { dg-final { scan-assembler "post-label.*(2 halfwords)" } } */
+/* { dg-final { scan-assembler "post-label.*(8 halfwords)" } } */
+/* { dg-final { scan-assembler "post-label.*(32 halfwords)" } } */
+/* { dg-final { scan-assembler-times "alignment for hotpatch" 3 } } */
+/* { dg-final { scan-assembler-times "\.align\t8" 6 } } */
+/* { dg-final { scan-assembler "nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr.*\n.*nopr" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-3.c b/gcc/testsuite/gcc.target/s390/hotpatch-3.c
index 8a2ab538e8d..ec4a978f72e 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-3.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-3.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(2 halfwords)" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-4.c b/gcc/testsuite/gcc.target/s390/hotpatch-4.c
index 9a69459797e..d55e71d3d69 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-4.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-4.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(3 halfwords)" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-times "brcl\t0, 0" 1 } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-5.c b/gcc/testsuite/gcc.target/s390/hotpatch-5.c
index b3d990f499a..f77d83aea07 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-5.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-5.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(4 halfwords)" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-times "brcl\t0, 0" 1 } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-6.c b/gcc/testsuite/gcc.target/s390/hotpatch-6.c
index 10ba5580b0d..330cf5d011f 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-6.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-6.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(5 halfwords)" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-times "brcl\t0, 0" 1 } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-7.c b/gcc/testsuite/gcc.target/s390/hotpatch-7.c
index edf67d3e22e..2f24e3cc152 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-7.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-7.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(6 halfwords)" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-not "nop\t0" } } */
 /* { dg-final { scan-assembler-times "brcl\t0, 0" 2 } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-8.c b/gcc/testsuite/gcc.target/s390/hotpatch-8.c
index a179c4a633c..7b266bd463e 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-8.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-8.c
@@ -11,6 +11,9 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(3 halfwords)" } } */
 /* { dg-final { scan-assembler-times "nopr\t%r7" 1 } } */
 /* { dg-final { scan-assembler-times "nop\t0" 1 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
+/* { dg-final { scan-assembler-not "alignment for hotpatch" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-9.c b/gcc/testsuite/gcc.target/s390/hotpatch-9.c
index c4e21f2d3de..c0ad319c0bb 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-9.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-9.c
@@ -11,6 +11,8 @@ void hp1(void)
 }
 
 /* Check number of occurences of certain instructions.  */
+/* { dg-final { scan-assembler-not "pre-label NOPs" } } */
+/* { dg-final { scan-assembler "post-label.*(4 halfwords)" } } */
 /* { dg-final { scan-assembler-not "nopr\t%r7" } } */
 /* { dg-final { scan-assembler-times "nop\t0" 2 } } */
 /* { dg-final { scan-assembler-not "brcl\t0, 0" } } */
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-compile-16.c b/gcc/testsuite/gcc.target/s390/hotpatch-compile-16.c
index 3c5c7827206..2e8291ede34 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-compile-16.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-compile-16.c
@@ -1,4 +1,4 @@
-/* A warning will be issued when requesting hotpatching on a nested function.  */
+/* Functional tests for the function hotpatching feature.  */
 
 /* { dg-do compile } */
 /* { dg-options "-O3 -mzarch" } */
@@ -17,7 +17,7 @@ fn_t hp1(void)
 fn_t hp2(void)
 {
   __attribute__ ((hotpatch(1,2)))
-  int nested2(void) /* { dg-warning "hotpatching is not compatible with nested functions" } */
+  int nested2(void)
   { return 2; }
 
   return nested2;