AVR: target/114132 - Code sets up a frame pointer without need.

The condition CUMULATIVE_ARGS.nregs == 0 in avr_frame_pointer_required_p()
means that no more argument registers are left, but that's not the same
condition that tells whether an argument pointer is required.

	PR target/114132
gcc/
	* config/avr/avr.h (CUMULATIVE_ARGS) <has_stack_args>: New field.
	* config/avr/avr.cc (avr_init_cumulative_args): Initialize it.
	(avr_function_arg): Set it.
	(avr_frame_pointer_required_p): Use it instead of .nregs.

gcc/testsuite/
	* gcc.target/avr/pr114132-1.c: New test.
	* gcc.target/avr/torture/pr114132-2.c: New test.

4 files changed, 47 insertions, 1 deletions

diff --git a/gcc/config/avr/avr.cc b/gcc/config/avr/avr.cc
index 655a8e8..478463b 100644
--- a/gcc/config/avr/avr.cc
+++ b/gcc/config/avr/avr.cc
@@ -3565,6 +3565,7 @@ avr_init_cumulative_args (CUMULATIVE_ARGS *cum, tree fntype, rtx libname,
 {
   cum->nregs = AVR_TINY ? 6 : 18;
   cum->regno = FIRST_CUM_REG;
+  cum->has_stack_args = 0;
   if (!libname && stdarg_p (fntype))
     cum->nregs = 0;
 
@@ -3605,6 +3606,8 @@ avr_function_arg (cumulative_args_t cum_v, const function_arg_info &arg)
   if (cum->nregs && bytes <= cum->nregs)
     return gen_rtx_REG (arg.mode, cum->regno - bytes);
 
+  cum->has_stack_args = 1;
+
   return NULL_RTX;
 }
 
@@ -6014,6 +6017,8 @@ out_movhi_mr_r (rtx_insn *insn, rtx op[], int *plen)
   return "";
 }
 
+
+/* Implement `TARGET_FRAME_POINTER_REQUIRED'.  */
 /* Return 1 if frame pointer for current function required.  */
 
 static bool
@@ -6022,7 +6027,7 @@ avr_frame_pointer_required_p (void)
   return (cfun->calls_alloca
 	  || cfun->calls_setjmp
 	  || cfun->has_nonlocal_label
-	  || crtl->args.info.nregs == 0
+	  || crtl->args.info.has_stack_args
 	  || get_frame_size () > 0);
 }
 
diff --git a/gcc/config/avr/avr.h b/gcc/config/avr/avr.h
index ff2738d..56211fa 100644
--- a/gcc/config/avr/avr.h
+++ b/gcc/config/avr/avr.h
@@ -333,6 +333,10 @@ typedef struct avr_args
 
   /* Next available register number */
   int regno;
+
+  /* Whether some of the arguments are passed on the stack,
+     and hence an arg pointer is needed.  */
+  int has_stack_args;
 } CUMULATIVE_ARGS;
 
 #define INIT_CUMULATIVE_ARGS(CUM, FNTYPE, LIBNAME, FNDECL, N_NAMED_ARGS) \
diff --git a/gcc/testsuite/gcc.target/avr/pr114132-1.c b/gcc/testsuite/gcc.target/avr/pr114132-1.c
new file mode 100644
index 0000000..209eca8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/avr/pr114132-1.c
@@ -0,0 +1,15 @@
+/* { dg-additional-options "-Os -std=c99" } */
+
+#ifdef __AVR_TINY__
+int func (int a, int b, char c)
+#else
+int func (long long a, long long b, char c)
+#endif
+{
+    (void) a;
+    (void) b;
+
+    return c;
+}
+
+/* { dg-final { scan-assembler-not "push r28" } } */
diff --git a/gcc/testsuite/gcc.target/avr/torture/pr114132-2.c b/gcc/testsuite/gcc.target/avr/torture/pr114132-2.c
new file mode 100644
index 0000000..c2bcbac
--- /dev/null
+++ b/gcc/testsuite/gcc.target/avr/torture/pr114132-2.c
@@ -0,0 +1,22 @@
+/* { dg-do run } */
+/* { dg-additional-options "-std=c99" } */
+
+__attribute__((noinline,noclone))
+#ifdef __AVR_TINY__
+int func (int a, int b, char c)
+#else
+int func (long long a, long long b, char c)
+#endif
+{
+    (void) a;
+    (void) b;
+    return 10 + c;
+}
+
+int main (void)
+{
+    if (func (0, 0, 91) != 101)
+        __builtin_abort();
+    return 0;
+}
+