[PATCH] MIPS: Fixed the problem that the nop instruction is inserted at the wrong position after enabling '-fpatchable-function-entry='

[Lulu Cheng]

Because MIPS function symbol is generated in the prologue function,
this nop generation should be done in prologue.

OK for trunk?

        PR target/99217
gcc/ChangeLog:

        * config/mips/mips.cc (mips_start_function_definition):
        Implements the functionality of '-fpatchable-function-entry='.
        (mips_print_patchable_function_entry): Define empty function.
        (TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY): Define macro.

Change-Id: If156e635568edb6560d9230f6967e01d207d46b2
---
 gcc/config/mips/mips.cc | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
index 492fa285477..7478e376fdf 100644
--- a/gcc/config/mips/mips.cc
+++ b/gcc/config/mips/mips.cc
@@ -7478,6 +7478,9 @@ static void
 mips_start_function_definition (const char *name, bool mips16_p,
                                tree decl ATTRIBUTE_UNUSED)
 {
+  unsigned HOST_WIDE_INT patch_area_size = crtl->patch_area_size;
+  unsigned HOST_WIDE_INT patch_area_entry = crtl->patch_area_entry;
+
   if (mips16_p)
     fprintf (asm_out_file, "\t.set\tmips16\n");
   else
@@ -7490,6 +7493,10 @@ mips_start_function_definition (const char *name, bool 
mips16_p,
     fprintf (asm_out_file, "\t.set\tnomicromips\n");
 #endif
 
+  /* Emit the patching area before the entry label, if any.  */
+  if (patch_area_entry > 0)
+    default_print_patchable_function_entry (asm_out_file,
+                                           patch_area_entry, true);
   if (!flag_inhibit_size_directive)
     {
       fputs ("\t.ent\t", asm_out_file);
@@ -7501,6 +7508,13 @@ mips_start_function_definition (const char *name, bool 
mips16_p,
 
   /* Start the definition proper.  */
   ASM_OUTPUT_FUNCTION_LABEL (asm_out_file, name, decl);
+
+  /* And the area after the label.  Record it if we haven't done so yet.  */
+  if (patch_area_size > patch_area_entry)
+    default_print_patchable_function_entry (asm_out_file,
+                                           patch_area_size
+                                           - patch_area_entry,
+                                           patch_area_entry == 0);
 }
 
 /* End a function definition started by mips_start_function_definition.  */
@@ -23314,6 +23328,20 @@ mips_bit_clear_p (enum machine_mode mode, unsigned 
HOST_WIDE_INT m)
   return false;
 }
 
+/* define TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY */
+
+/* The MIPS function start is implemented in the prologue function.
+   TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY needs to be inserted
+   before or after the function name, so this function does not
+   use a public implementation. This function is implemented in
+   mips_start_function_definition. */
+
+void
+mips_print_patchable_function_entry (FILE *file,
+                                    unsigned HOST_WIDE_INT patch_area_size,
+                                    bool record_p)
+{}
+
 /* Initialize the GCC target structure.  */
 #undef TARGET_ASM_ALIGNED_HI_OP
 #define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
@@ -23627,6 +23655,10 @@ mips_bit_clear_p (enum machine_mode mode, unsigned 
HOST_WIDE_INT m)
 #undef TARGET_DOCUMENTATION_NAME
 #define TARGET_DOCUMENTATION_NAME "MIPS"
 
+#undef TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY
+#define TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY \
+mips_print_patchable_function_entry
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-mips.h"
-- 
2.34.1