[AArch64] Remove aarch64_frame_pointer_required

To implement -fomit-leaf-frame-pointer, there are 2 places where we need
to check whether we have to use a frame chain (since register allocation
may allocate LR in a leaf function that omits the frame pointer, but if
LR is spilled we must emit a frame chain).  To simplify this do not force
frame_pointer_needed via aarch64_frame_pointer_required, but enable the
frame chain in aarch64_layout_frame.  Now aarch64_frame_pointer_required
can be removed and aarch64_can_eliminate is simplified.

    gcc/
	* config/aarch64/aarch64.c (aarch64_frame_pointer_required)
	Remove.
	(aarch64_layout_frame): Initialise emit_frame_chain.
	(aarch64_can_eliminate): Remove omit leaf frame pointer code.
	(TARGET_FRAME_POINTER_REQUIRED): Remove define.

    testsuite/
	* gcc.target/aarch64/dwarf-cfa-reg.c: Update.

From-SVN: r254533

gcc/ChangeLog

+2017-11-08  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* config/aarch64/aarch64.c (aarch64_frame_pointer_required)
+	Remove.
+	(aarch64_layout_frame): Initialise emit_frame_chain.
+	(aarch64_can_eliminate): Remove omit leaf frame pointer code.
+	(TARGET_FRAME_POINTER_REQUIRED): Remove define.
+
 2017-11-08  Martin Liska  <mliska@suse.cz>
 
 	* gimplify.c (expand_FALLTHROUGH_r): Simplify usage

gcc/config/aarch64/aarch64.c

@@ -2891,21 +2891,6 @@ aarch64_output_probe_stack_range (rtx reg1, rtx reg2)
   return "";
 }
 
-static bool
-aarch64_frame_pointer_required (void)
-{
-  /* Use the frame pointer if enabled and it is not a leaf function, unless
-     leaf frame pointer omission is disabled.  If the frame pointer is enabled,
-     force the frame pointer in leaf functions which use LR.  */
-  if (flag_omit_frame_pointer == 2
-      && !(flag_omit_leaf_frame_pointer
-	   && crtl->is_leaf
-	   && !df_regs_ever_live_p (LR_REGNUM)))
-    return true;
-
-  return false;
-}
-
 /* Mark the registers that need to be saved by the callee and calculate
    the size of the callee-saved registers area and frame record (both FP
    and LR may be omitted).  */
@@ -2922,6 +2907,14 @@ aarch64_layout_frame (void)
   cfun->machine->frame.emit_frame_chain
     = frame_pointer_needed || crtl->calls_eh_return;
 
+  /* Emit a frame chain if the frame pointer is enabled.
+     If -momit-leaf-frame-pointer is used, do not use a frame chain
+     in leaf functions which do not use LR.  */
+  if (flag_omit_frame_pointer == 2
+      && !(flag_omit_leaf_frame_pointer && crtl->is_leaf
+	   && !df_regs_ever_live_p (LR_REGNUM)))
+    cfun->machine->frame.emit_frame_chain = true;
+
 #define SLOT_NOT_REQUIRED (-2)
 #define SLOT_REQUIRED     (-1)
 
@@ -5939,17 +5932,6 @@ aarch64_can_eliminate (const int from, const int to)
 
       return false;
     }
-  else
-    {
-      /* If we decided that we didn't need a leaf frame pointer but then used
-	 LR in the function, then we'll want a frame pointer after all, so
-	 prevent this elimination to ensure a frame pointer is used.  */
-      if (to == STACK_POINTER_REGNUM
-	  && flag_omit_frame_pointer == 2
-	  && flag_omit_leaf_frame_pointer
-	  && df_regs_ever_live_p (LR_REGNUM))
-	return false;
-    }
 
   return true;
 }
@@ -15261,9 +15243,6 @@ aarch64_run_selftests (void)
 #undef TARGET_FUNCTION_VALUE_REGNO_P
 #define TARGET_FUNCTION_VALUE_REGNO_P aarch64_function_value_regno_p
 
-#undef TARGET_FRAME_POINTER_REQUIRED
-#define TARGET_FRAME_POINTER_REQUIRED aarch64_frame_pointer_required
-
 #undef TARGET_GIMPLE_FOLD_BUILTIN
 #define TARGET_GIMPLE_FOLD_BUILTIN aarch64_gimple_fold_builtin
 

gcc/testsuite/ChangeLog

+2017-11-08  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* gcc.target/aarch64/dwarf-cfa-reg.c: Update.
+
 2017-11-08  Javier Miranda  <miranda@adacore.com>
 
 	* gnat.dg/overriding_ops2.adb, gnat.dg/overriding_ops2.ads,

gcc/testsuite/gcc.target/aarch64/dwarf-cfa-reg.c

@@ -3,7 +3,7 @@
 /* { dg-options "-O0 -gdwarf-2" } */
 /* { dg-final { scan-assembler ".cfi_restore 30" } } */
 /* { dg-final { scan-assembler ".cfi_restore 29" } } */
-/* { dg-final { scan-assembler ".cfi_def_cfa 31, 0" } } */
+/* { dg-final { scan-assembler ".cfi_def_cfa_offset 0" } } */
 /* { dg-final { scan-assembler "ret" } } */
 
 int bar (unsigned int);