[AArch64] Enable shrink wrapping.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@215508 138bc75d-0d04-0410-961f-82ee72b054a4

3 files changed, 34 insertions, 0 deletions

diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 367253b0d78..e32ef645b68 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -213,6 +213,7 @@ bool aarch64_simd_valid_immediate (rtx, enum machine_mode, bool,
 				   struct simd_immediate_info *);
 bool aarch64_symbolic_address_p (rtx);
 bool aarch64_uimm12_shift (HOST_WIDE_INT);
+bool aarch64_use_return_insn_p (void);
 const char *aarch64_output_casesi (rtx *);
 const char *aarch64_rewrite_selected_cpu (const char *name);
 
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 15c7be697d3..348308109a9 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -2340,6 +2340,26 @@ aarch64_expand_prologue (void)
     }
 }
 
+/* Return TRUE if we can use a simple_return insn.
+
+   This function checks whether the callee saved stack is empty, which
+   means no restore actions are need. The pro_and_epilogue will use
+   this to check whether shrink-wrapping opt is feasible.  */
+
+bool
+aarch64_use_return_insn_p (void)
+{
+  if (!reload_completed)
+    return false;
+
+  if (crtl->profile)
+    return false;
+
+  aarch64_layout_frame ();
+
+  return cfun->machine->frame.frame_size == 0;
+}
+
 /* Generate the epilogue instructions for returning from a function.  */
 void
 aarch64_expand_epilogue (bool for_sibcall)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index f15a516bb05..74b554ec4df 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -360,6 +360,19 @@
   [(set_attr "type" "branch")]
 )
 
+(define_expand "return"
+  [(simple_return)]
+  "aarch64_use_return_insn_p ()"
+  ""
+)
+
+(define_insn "simple_return"
+  [(simple_return)]
+  ""
+  "ret"
+  [(set_attr "type" "branch")]
+)
+
 (define_insn "eh_return"
   [(unspec_volatile [(match_operand:DI 0 "register_operand" "r")]
     UNSPECV_EH_RETURN)]