[AArch64] Let LR register alloctable

gcc/
    * config/aarch64/aarch64.h (CALL_USED_REGISTERS): Mark LR as caller-save.
    (EPILOGUE_USES): Guard the check by epilogue_completed.
    * config/aarch64/aarch64.c (aarch64_layout_frame): Explictly check for LR.
    (aarch64_can_eliminate): Check LR_REGNUM liveness.

  gcc/testsuite/
    * gcc.target/aarch64/lr_free_1.c: New testcase for -fomit-frame-pointer.
    * gcc.target/aarch64/lr_free_2.c: New testcase for leaf
    -fno-omit-frame-pointer.

From-SVN: r217431

gcc/ChangeLog

@@ -1,3 +1,12 @@
+2014-11-12  Jiong Wang  <jiong.wang@arm.com>
+
+	* config/aarch64/aarch64.h (CALL_USED_REGISTERS): Mark LR as
+	caller-save.
+	(EPILOGUE_USES): Guard the check by epilogue_completed.
+	* config/aarch64/aarch64.c (aarch64_layout_frame): Explictly check for
+	LR.
+	(aarch64_can_eliminate): Check LR_REGNUM liveness.
+
 2014-11-12  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
 
 	* config/arm/arm.c (*<arith_shift_insn>_shiftsi): Fix typo.

gcc/config/aarch64/aarch64.c

@@ -1901,7 +1901,8 @@ aarch64_layout_frame (void)
   /* ... and any callee saved register that dataflow says is live.  */
   for (regno = R0_REGNUM; regno <= R30_REGNUM; regno++)
     if (df_regs_ever_live_p (regno)
-	&& !call_used_regs[regno])
+	&& (regno == R30_REGNUM
+	    || !call_used_regs[regno]))
       cfun->machine->frame.reg_offset[regno] = SLOT_REQUIRED;
 
   for (regno = V0_REGNUM; regno <= V31_REGNUM; regno++)
@@ -4418,6 +4419,16 @@ 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_leaf_frame_pointer
+	  && df_regs_ever_live_p (LR_REGNUM))
+	return false;
+    }
 
   return true;
 }

gcc/config/aarch64/aarch64.h

@@ -272,7 +272,7 @@ extern unsigned long aarch64_tune_flags;
     1, 1, 1, 1,   1, 1, 1, 1,	/* R0 - R7 */		\
     1, 1, 1, 1,   1, 1, 1, 1,	/* R8 - R15 */		\
     1, 1, 1, 0,   0, 0, 0, 0,	/* R16 - R23 */		\
-    0, 0, 0, 0,   0, 1, 0, 1,	/* R24 - R30, SP */	\
+    0, 0, 0, 0,   0, 1, 1, 1,	/* R24 - R30, SP */	\
     1, 1, 1, 1,   1, 1, 1, 1,	/* V0 - V7 */		\
     0, 0, 0, 0,   0, 0, 0, 0,	/* V8 - V15 */		\
     1, 1, 1, 1,   1, 1, 1, 1,   /* V16 - V23 */         \
@@ -331,7 +331,7 @@ extern unsigned long aarch64_tune_flags;
    considered live at the start of the called function.  */
 
 #define EPILOGUE_USES(REGNO) \
-  ((REGNO) == LR_REGNUM)
+  (epilogue_completed && (REGNO) == LR_REGNUM)
 
 /* EXIT_IGNORE_STACK should be nonzero if, when returning from a function,
    the stack pointer does not matter.  The value is tested only in

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2014-11-12  Jiong Wang  <jiong.wang@arm.com>
+
+	* gcc.target/aarch64/lr_free_1.c: New testcase for -fomit-frame-pointer.
+	* gcc.target/aarch64/lr_free_2.c: New testcase for leaf
+	-fno-omit-frame-pointer.
+
 2014-11-12  Marek Polacek  <polacek@redhat.com>
 
 	* lib/gcc-dg.exp (${tool}_load): Call prune_file_path instead

gcc/testsuite/gcc.target/aarch64/lr_free_1.c

@@ -0,0 +1,38 @@
+/* { dg-do run } */
+/* { dg-options "-fno-inline -O2 -fomit-frame-pointer -ffixed-x2 -ffixed-x3 -ffixed-x4 -ffixed-x5 -ffixed-x6 -ffixed-x7 -ffixed-x8 -ffixed-x9 -ffixed-x10 -ffixed-x11 -ffixed-x12 -ffixed-x13 -ffixed-x14 -ffixed-x15 -ffixed-x16 -ffixed-x17 -ffixed-x18 -ffixed-x19 -ffixed-x20 -ffixed-x21 -ffixed-x22 -ffixed-x23 -ffixed-x24 -ffixed-x25 -ffixed-x26 -ffixed-x27 -ffixed-28 -ffixed-29 --save-temps -mgeneral-regs-only -fno-ipa-cp" } */
+
+extern void abort ();
+
+int
+dec (int a, int b)
+{
+  return a + b;
+}
+
+int
+cal (int a, int b)
+{
+  int sum1 = a * b;
+  int sum2 = a / b;
+  int sum = dec (sum1, sum2);
+  return a + b + sum + sum1 + sum2;
+}
+
+int
+main (int argc, char **argv)
+{
+  int ret = cal (2, 1);
+
+  if (ret != 11)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-assembler-times "str\tx30, \\\[sp, -\[0-9\]+\\\]!" 2 } } */
+/* { dg-final { scan-assembler "str\tw30, \\\[sp, \[0-9\]+\\\]" } } */
+
+/* { dg-final { scan-assembler "ldr\tw30, \\\[sp, \[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler-times "ldr\tx30, \\\[sp\\\], \[0-9\]+" 2 } } */
+
+/* { dg-final { cleanup-saved-temps } } */

gcc/testsuite/gcc.target/aarch64/lr_free_2.c

@@ -0,0 +1,29 @@
+/* { dg-do run } */
+/* { dg-options "-fno-inline -O2 -ffixed-x2 -ffixed-x3 -ffixed-x4 -ffixed-x5 -ffixed-x6 -ffixed-x7 -ffixed-x8 -ffixed-x9 -ffixed-x10 -ffixed-x11 -ffixed-x12 -ffixed-x13 -ffixed-x14 -ffixed-x15 -ffixed-x16 -ffixed-x17 -ffixed-x18 -ffixed-x19 -ffixed-x20 -ffixed-x21 -ffixed-x22 -ffixed-x23 -ffixed-x24 -ffixed-x25 -ffixed-x26 -ffixed-x27 -ffixed-x28 --save-temps -mgeneral-regs-only -fno-ipa-cp -fdump-rtl-ira" } */
+
+extern void abort ();
+
+int
+cal (int a, int b)
+{
+  /* { dg-final { scan-assembler-times "stp\tx29, x30, \\\[sp, -\[0-9\]+\\\]!" 2 } } */
+  int sum = a + b;
+  int sum1 = a * b;
+  /* { dg-final { scan-assembler-times "ldp\tx29, x30, \\\[sp\\\], \[0-9\]+" 2 } } */
+  /* { dg-final { scan-rtl-dump "assign reg 30" "ira" } } */
+  return (a + b + sum + sum1);
+}
+
+int
+main (int argc, char **argv)
+{
+  int ret = cal (1, 2);
+
+  if (ret != 8)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { cleanup-saved-temps } } */
+/* { dg-final { cleanup-rtl-dump "ira" } } */