tm.texi (TARGET_STRUCT_VALUE_RTX): Document new value 2 for incoming.

gcc/

2006-04-04  Carlos O'Donell  <carlos@codesourcery.com>

	* doc/tm.texi (TARGET_STRUCT_VALUE_RTX): Document
	new value 2 for incoming.
	* function.c (expand_function_start): Call struct_value_rtx
	with incoming as 2.
	* config/sparc/sparc.md: Comment updated_return.
	* config/sparc/sparc.opt: Add -mstd-struct-return option.
	* config/sparc/sparc.c (sparc_struct_value_rtx): Use standard
	struct return if sparc_std_struct_return and incoming is 2.
	(print_operand): Do not adjust return if
	sparc_std_struct_return.

gcc/testsuite/

2006-04-04  Carlos O'Donell  <carlos@codesourcery.com>

	* gcc.target/sparc/struct-ret-check.c: New test.

From-SVN: r112672

3 files changed, 57 insertions, 4 deletions

diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 709a92b..e880226 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -5425,7 +5425,7 @@ sparc_return_in_memory (tree type, tree fntype ATTRIBUTE_UNUSED)
    Return where to find the structure return value address.  */
 
 static rtx
-sparc_struct_value_rtx (tree fndecl ATTRIBUTE_UNUSED, int incoming)
+sparc_struct_value_rtx (tree fndecl, int incoming)
 {
   if (TARGET_ARCH64)
     return 0;
@@ -5440,6 +5440,46 @@ sparc_struct_value_rtx (tree fndecl ATTRIBUTE_UNUSED, int incoming)
 	mem = gen_rtx_MEM (Pmode, plus_constant (stack_pointer_rtx,
 						 STRUCT_VALUE_OFFSET));
 
+      /* Only follow the SPARC ABI for fixed-size structure returns. 
+         Variable size structure returns are handled per the normal 
+         procedures in GCC. This is enabled by -mstd-struct-return */
+      if (incoming == 2 
+	  && sparc_std_struct_return
+	  && TYPE_SIZE_UNIT (TREE_TYPE (fndecl))
+	  && TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (fndecl))) == INTEGER_CST)
+	{
+	  /* We must check and adjust the return address, as it is
+	     optional as to whether the return object is really
+	     provided.  */
+	  rtx ret_rtx = gen_rtx_REG (Pmode, 31);
+	  rtx scratch = gen_reg_rtx (SImode);
+	  rtx endlab = gen_label_rtx (); 
+
+	  /* Calculate the return object size */
+	  tree size = TYPE_SIZE_UNIT (TREE_TYPE (fndecl));
+	  rtx size_rtx = GEN_INT (TREE_INT_CST_LOW (size) & 0xfff);
+	  /* Construct a temporary return value */
+	  rtx temp_val = assign_stack_local (Pmode, TREE_INT_CST_LOW (size), 0);
+
+	  /* Implement SPARC 32-bit psABI callee returns struck checking
+	     requirements: 
+	    
+	      Fetch the instruction where we will return to and see if
+	     it's an unimp instruction (the most significant 10 bits
+	     will be zero).  */
+	  emit_move_insn (scratch, gen_rtx_MEM (SImode,
+						plus_constant (ret_rtx, 8)));
+	  /* Assume the size is valid and pre-adjust */
+	  emit_insn (gen_add3_insn (ret_rtx, ret_rtx, GEN_INT (4)));
+	  emit_cmp_and_jump_insns (scratch, size_rtx, EQ, const0_rtx, SImode, 0, endlab);
+	  emit_insn (gen_sub3_insn (ret_rtx, ret_rtx, GEN_INT (4)));
+	  /* Assign stack temp: 
+	     Write the address of the memory pointed to by temp_val into
+	     the memory pointed to by mem */
+	  emit_move_insn (mem, XEXP (temp_val, 0));
+	  emit_label (endlab);
+	}
+
       set_mem_alias_set (mem, struct_value_alias_set);
       return mem;
     }
@@ -6639,9 +6679,14 @@ print_operand (FILE *file, rtx x, int code)
 	 so we have to account for it.  This insn is used in the 32-bit ABI
 	 when calling a function that returns a non zero-sized structure. The
 	 64-bit ABI doesn't have it.  Be careful to have this test be the same
-	 as that used on the call.  */
+	 as that used on the call. The exception here is that when 
+	 sparc_std_struct_return is enabled, the psABI is followed exactly
+	 and the adjustment is made by the code in sparc_struct_value_rtx. 
+	 The call emitted is the same when sparc_std_struct_return is 
+	 present. */
      if (! TARGET_ARCH64
 	 && current_function_returns_struct
+	 && ! sparc_std_struct_return
 	 && (TREE_CODE (DECL_SIZE (DECL_RESULT (current_function_decl)))
 	     == INTEGER_CST)
 	 && ! integer_zerop (DECL_SIZE (DECL_RESULT (current_function_decl))))
diff --git a/gcc/config/sparc/sparc.md b/gcc/config/sparc/sparc.md
index b6ebb82..ed68f1e 100644
--- a/gcc/config/sparc/sparc.md
+++ b/gcc/config/sparc/sparc.md
@@ -7094,8 +7094,13 @@
   DONE;
 })
 
-;; This is a bit of a hack.  We're incrementing a fixed register (%i7),
-;; and parts of the compiler don't want to believe that the add is needed.
+;; Adjust the return address conditionally. If the value of op1 is equal
+;; to all zero then adjust the return address i.e. op0 = op0 + 4.
+;; This is technically *half* the check required by the 32-bit SPARC
+;; psABI. This check only ensures that an "unimp" insn was written by
+;; the caller, but doesn't check to see if the expected size matches
+;; (this is encoded in the 12 lower bits). This check is obsolete and
+;; only used by the above code "untyped_return".
 
 (define_insn "update_return"
   [(unspec:SI [(match_operand:SI 0 "register_operand" "r")
diff --git a/gcc/config/sparc/sparc.opt b/gcc/config/sparc/sparc.opt
index da50e1a..8cdf11c 100644
--- a/gcc/config/sparc/sparc.opt
+++ b/gcc/config/sparc/sparc.opt
@@ -99,6 +99,9 @@ mcmodel=
 Target RejectNegative Joined Var(sparc_cmodel_string)
 Use given SPARC-V9 code model
 
+mstd-struct-return
+Target Report RejectNegative Var(sparc_std_struct_return)
+Enable strict 32-bit psABI struct return checking.
 
 Mask(LITTLE_ENDIAN)
 ;; Generate code for little-endian