[PATCH, ARM] Enable tail call optimization for long call

[Jiong Wang <jiong dot wang at arm dot com>]

This patch enables tail call optimization for long call on arm.

Previously we have too strict check on arm_function_ok_for_sibcall and
be lack of the support on sibcall/sibcall_value expand that long call tail oppportunities are lost.

OK for next next stage 1?

thanks.

--
Jiong


gcc/
  * config/arm/predicates.md (call_insn_operand): Add long_call check.
  * config/arm/arm.md (sibcall, sibcall_value): Force the address to reg for long_call.
  * config/aarch64/aarch64.c (arm_function_ok_for_sibcall): Remove long_call restriction.

gcc/testsuite
  gcc.target/arm/tail-long-call.c: New test.

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index d5f9ff3..8dcdfa8 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -6087,11 +6087,6 @@ arm_function_ok_for_sibcall (tree decl, tree exp)
   if (TARGET_VXWORKS_RTP && flag_pic && !targetm.binds_local_p (decl))
     return false;
 
-  /* Cannot tail-call to long calls, since these are out of range of
-     a branch instruction.  */
-  if (decl && arm_is_long_call_p (decl))
-    return false;
-
   /* If we are interworking and the function is not declared static
      then we can't tail-call it unless we know that it exists in this
      compilation unit (since it might be a Thumb routine).  */
diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 2ddda02..fe285f0 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -9444,8 +9444,10 @@
   "TARGET_32BIT"
   "
   {
-    if (!REG_P (XEXP (operands[0], 0))
-       && (GET_CODE (XEXP (operands[0], 0)) != SYMBOL_REF))
+    if ((!REG_P (XEXP (operands[0], 0))
+	 && GET_CODE (XEXP (operands[0], 0)) != SYMBOL_REF)
+	|| (GET_CODE (XEXP (operands[0], 0)) == SYMBOL_REF
+	    && arm_is_long_call_p (SYMBOL_REF_DECL (XEXP (operands[0], 0)))))
      XEXP (operands[0], 0) = force_reg (SImode, XEXP (operands[0], 0));
 
     if (operands[2] == NULL_RTX)
@@ -9462,8 +9464,10 @@
   "TARGET_32BIT"
   "
   {
-    if (!REG_P (XEXP (operands[1], 0)) &&
-       (GET_CODE (XEXP (operands[1],0)) != SYMBOL_REF))
+    if ((!REG_P (XEXP (operands[1], 0))
+	 && GET_CODE (XEXP (operands[1], 0)) != SYMBOL_REF)
+	|| (GET_CODE (XEXP (operands[1], 0)) == SYMBOL_REF
+	    && arm_is_long_call_p (SYMBOL_REF_DECL (XEXP (operands[1], 0)))))
      XEXP (operands[1], 0) = force_reg (SImode, XEXP (operands[1], 0));
 
     if (operands[3] == NULL_RTX)
diff --git a/gcc/config/arm/predicates.md b/gcc/config/arm/predicates.md
index ce5c9a8..3673343 100644
--- a/gcc/config/arm/predicates.md
+++ b/gcc/config/arm/predicates.md
@@ -673,5 +673,6 @@
        (match_code "reg" "0")))
 
 (define_predicate "call_insn_operand"
-  (ior (match_code "symbol_ref")
+  (ior (and (match_code "symbol_ref")
+	    (match_test "!arm_is_long_call_p (SYMBOL_REF_DECL (op))"))
        (match_operand 0 "s_register_operand")))
diff --git a/gcc/testsuite/gcc.target/arm/tail-long-call.c b/gcc/testsuite/gcc.target/arm/tail-long-call.c
new file mode 100644
index 0000000..9b27468
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/tail-long-call.c
@@ -0,0 +1,12 @@
+/* { dg-skip-if "need at least armv5te" { *-*-* } { "-march=armv[234]*" "-mthumb" } { "" } } */
+/* { dg-options "-O2 -march=armv5te -marm" } */
+/* { dg-final { scan-assembler "bx" } } */
+/* { dg-final { scan-assembler-not "blx" } } */
+
+int lcal (int) __attribute__ ((long_call));
+
+int
+dec (int a)
+{
+  return lcal (a);
+}