Microblaze: Fixed missing save of r18 in fast_interrupt. Register 18 is used as…

Microblaze: Fixed missing save of r18 in fast_interrupt. Register 18 is used as a clobber register, and must be stored when entering a fast_interrupt. Before this fix, register 18 was only saved if it was used directly in the interrupt function.

    However, if the fast_interrupt function called a function that used
    r18, the register would not be saved, and thus be mangled
    upon returning from the interrupt.

	* config/microblaze/microblaze.c (microblaze_must_save_register): Check
	for fast_interrupt.

gcc/ChangeLog

 2020-04-05 Nagaraju Mekala <nmekala@xilix.com>
-    
-        * gcc/config/microblaze/microblaze.md (trap): Update output pattern.
 
-        * gcc/testsuite/gcc.target/microblaze/others/builtin-trap.c
-        (dg-final): update in the scan-assembler instruction
+	* config/microblaze/microblaze.c (microblaze_must_save_register): Check
+	for fast_interrupt.
+ 
+	* config/microblaze/microblaze.md (trap): Update output pattern.
 
 2020-04-04  Hannes Domani  <ssbssa@yahoo.de>
 	    Jakub Jelinek  <jakub@redhat.com>

gcc/config/microblaze/microblaze.c

@@ -2035,7 +2035,7 @@ microblaze_must_save_register (int regno)
     {
       if (df_regs_ever_live_p (regno) 
 	  || regno == MB_ABI_MSR_SAVE_REG
-	  || (interrupt_handler
+	  || ((interrupt_handler || fast_interrupt)
               && (regno == MB_ABI_ASM_TEMP_REGNUM
 	          || regno == MB_ABI_EXCEPTION_RETURN_ADDR_REGNUM)))
 	return 1;