mips.c (mips16_build_call_stub): Add CFI information to stubs with non-sibling calls.

gcc/
	* config/mips/mips.c (mips16_build_call_stub): Add CFI information
	to stubs with non-sibling calls.

libgcc/
	* config/mips/mips16.S (CALL_STUB_RET): Add CFI information.

From-SVN: r184379

4 files changed, 48 insertions, 16 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4292690..e052b4e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-02-19  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	* config/mips/mips.c (mips16_build_call_stub): Add CFI information
+	to stubs with non-sibling calls.
+
 2012-02-18  Sandra Loosemore  <sandra@codesourcery.com>
 
 	* doc/invoke.texi (-fira-* options): Copy-edit.
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 56863fa..2dfbb4b 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -6387,7 +6387,20 @@ mips16_build_call_stub (rtx retval, rtx *fn_ptr, rtx args_size, int fp_code)
       assemble_start_function (stubdecl, stubname);
       mips_start_function_definition (stubname, false);
 
-      if (!fp_ret_p)
+      if (fp_ret_p)
+	{
+	  fprintf (asm_out_file, "\t.cfi_startproc\n");
+
+	  /* Create a fake CFA 4 bytes below the stack pointer.
+	     This works around unwinders (like libgcc's) that expect
+	     the CFA for non-signal frames to be unique.  */
+	  fprintf (asm_out_file, "\t.cfi_def_cfa 29,-4\n");
+
+	  /* "Save" $sp in itself so we don't use the fake CFA.
+	     This is: DW_CFA_val_expression r29, { DW_OP_reg29 }.  */
+	  fprintf (asm_out_file, "\t.cfi_escape 0x16,29,1,0x6d\n");
+	}
+      else
 	{
 	  /* Load the address of the MIPS16 function into $25.  Do this
 	     first so that targets with coprocessor interlocks can use
@@ -6405,12 +6418,7 @@ mips16_build_call_stub (rtx retval, rtx *fn_ptr, rtx args_size, int fp_code)
 	 registers.  */
       mips_output_args_xfer (fp_code, 't');
 
-      if (!fp_ret_p)
-	{
-	  /* Jump to the previously-loaded address.  */
-	  output_asm_insn ("jr\t%^", NULL);
-	}
-      else
+      if (fp_ret_p)
 	{
 	  /* Save the return address in $18 and call the non-MIPS16 function.
 	     The stub's caller knows that $18 might be clobbered, even though
@@ -6418,6 +6426,7 @@ mips16_build_call_stub (rtx retval, rtx *fn_ptr, rtx args_size, int fp_code)
 	  fprintf (asm_out_file, "\tmove\t%s,%s\n",
 		   reg_names[GP_REG_FIRST + 18], reg_names[RETURN_ADDR_REGNUM]);
 	  output_asm_insn (MIPS_CALL ("jal", &fn, 0, -1), &fn);
+	  fprintf (asm_out_file, "\t.cfi_register 31,18\n");
 
 	  /* Move the result from floating-point registers to
 	     general registers.  */
@@ -6470,6 +6479,12 @@ mips16_build_call_stub (rtx retval, rtx *fn_ptr, rtx args_size, int fp_code)
 	      gcc_unreachable ();
 	    }
 	  fprintf (asm_out_file, "\tjr\t%s\n", reg_names[GP_REG_FIRST + 18]);
+	  fprintf (asm_out_file, "\t.cfi_endproc\n");
+	}
+      else
+	{
+	  /* Jump to the previously-loaded address.  */
+	  output_asm_insn ("jr\t%^", NULL);
 	}
 
 #ifdef ASM_DECLARE_FUNCTION_SIZE
diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 01a3ac2..15d9b08 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,7 @@
+2012-02-19  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	* config/mips/mips16.S (CALL_STUB_RET): Add CFI information.
+
 2012-02-15  Iain Sandoe  <iains@gcc.gnu.org>
 
 	PR libitm/52220
diff --git a/libgcc/config/mips/mips16.S b/libgcc/config/mips/mips16.S
index c82a55d..1899ab2 100644
--- a/libgcc/config/mips/mips16.S
+++ b/libgcc/config/mips/mips16.S
@@ -566,15 +566,23 @@ CALL_STUB_NO_RET (__mips16_call_stub_10, 10)
    being called is 16 bits, in which case the copy is unnecessary;
    however, it's faster to always do the copy.  */
 
-#define CALL_STUB_RET(NAME, CODE, MODE)	\
-STARTFN (NAME);				\
-	move	$18,$31;		\
-	STUB_ARGS_##CODE;		\
-	.set	noreorder;		\
-	jalr	$2;			\
-	move	$25,$2;			\
-	.set	reorder;		\
-	MOVE_##MODE##_RET (f, $18);	\
+#define CALL_STUB_RET(NAME, CODE, MODE)					\
+STARTFN (NAME);								\
+	.cfi_startproc;							\
+	/* Create a fake CFA 4 bytes below the stack pointer.  */	\
+	.cfi_def_cfa 29,-4;						\
+	/* "Save" $sp in itself so we don't use the fake CFA.		\
+	   This is: DW_CFA_val_expression r29, { DW_OP_reg29 }.  */	\
+	.cfi_escape 0x16,29,1,0x6d;					\
+	move	$18,$31;						\
+	.cfi_register 31,18;						\
+	STUB_ARGS_##CODE;						\
+	.set	noreorder;						\
+	jalr	$2;							\
+	move	$25,$2;							\
+	.set	reorder;						\
+	MOVE_##MODE##_RET (f, $18);					\
+	.cfi_endproc;							\
 	ENDFN (NAME)
 
 /* First, instantiate the single-float set.  */