config.gcc: Added support for --with-divide=[breaks|traps] for mips targets.

2004-09-07  David Daney  <ddaney@avtrex.com>

	* config.gcc: Added support for --with-divide=[breaks|traps] for
	mips targets.
	* config/mips/mips.h (MASK_DIVIDE_BREAKS): New target_flags bit.
	(TARGET_DIVIDE_TRAPS): New macro.
	(TARGET_SWITCHES): Added -mdivide-traps and -mdivide-breaks.
	(OPTION_DEFAULT_SPECS): Added --with-divide= support.
	* config/mips/mips.c (mips_idiv_insns): Generate proper count on
	GENERATE_DIVIDE_TRAPS.
	(mips_output_division): Emit conditional trap if
	GENERATE_DIVIDE_TRAPS is set.
	* doc/install.texi: Document --with-divide.
	* doc/invoke.texi: Document -mdivide-traps and -mdivide-breaks.

From-SVN: r87153

6 files changed, 93 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 732e788..476069b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,18 @@
+2004-09-07  David Daney  <ddaney@avtrex.com>
+
+	* config.gcc: Added support for --with-divide=[breaks|traps] for
+	mips targets.
+	* config/mips/mips.h (MASK_DIVIDE_BREAKS): New target_flags bit.
+	(TARGET_DIVIDE_TRAPS): New macro.
+	(TARGET_SWITCHES): Added -mdivide-traps and -mdivide-breaks.
+	(OPTION_DEFAULT_SPECS): Added --with-divide= support.
+	* config/mips/mips.c (mips_idiv_insns): Generate proper count on
+	GENERATE_DIVIDE_TRAPS.
+	(mips_output_division): Emit conditional trap if
+	GENERATE_DIVIDE_TRAPS is set.
+	* doc/install.texi: Document --with-divide.
+	* doc/invoke.texi: Document -mdivide-traps and -mdivide-breaks.
+
 2004-09-07  Caroline Tice  <ctice@apple.com>
 
 	* cfgrtl.c (rtl_verify_flow_info_1):  Add new edge flag,
diff --git a/gcc/config.gcc b/gcc/config.gcc
index 4f955a0..3c5b845 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -2425,7 +2425,7 @@ fi
 		;;
 
 	mips*-*-*)
-		supported_defaults="abi arch float tune"
+		supported_defaults="abi arch float tune divide"
 
 		case ${with_float} in
 		"" | soft | hard)
@@ -2446,6 +2446,15 @@ fi
 			exit 1
 			;;
 		esac
+
+		case ${with_divide} in
+		"" | breaks | traps)
+			# OK
+			;;
+		*)
+			echo "Unknown division check type use in --with-divide=$with_divide" 1>&2
+			exit 1
+		esac
 		;;
 
 	powerpc*-*-* | rs6000-*-*)
@@ -2687,7 +2696,7 @@ fi
 	esac
 
 	t=
-	all_defaults="abi cpu arch tune schedule float mode fpu"
+	all_defaults="abi cpu arch tune schedule float mode fpu divide"
 	for option in $all_defaults
 	do
 		eval "val=\$with_$option"
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 5f7e149..ea0eb7b 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -1375,7 +1375,13 @@ mips_idiv_insns (void)
 
   count = 1;
   if (TARGET_CHECK_ZERO_DIV)
-    count += 2;
+    {
+      if (GENERATE_DIVIDE_TRAPS)
+        count++;
+      else
+        count += 2;
+    }
+  
   if (TARGET_FIX_R4000 || TARGET_FIX_R4400)
     count++;
   return count;
@@ -8805,6 +8811,11 @@ mips_output_division (const char *division, rtx *operands)
 	  output_asm_insn (s, operands);
 	  s = "bnez\t%2,1f\n\tbreak\t7\n1:";
 	}
+      else if (GENERATE_DIVIDE_TRAPS)
+        {
+	  output_asm_insn (s, operands);
+	  s = "teq\t%2,%.,7";
+        }
       else
 	{
 	  output_asm_insn ("%(bne\t%2,%.,1f", operands);
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 8862e58..f9104bd 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -160,7 +160,8 @@ extern const struct mips_cpu_info *mips_tune_info;
 #define MASK_FIX_VR4120	   0x01000000   /* Work around VR4120 errata.  */
 #define MASK_VR4130_ALIGN  0x02000000	/* Perform VR4130 alignment opts.  */
 #define MASK_FP_EXCEPTIONS 0x04000000   /* FP exceptions are enabled.  */
-
+#define MASK_DIVIDE_BREAKS 0x08000000   /* Divide by zero check uses
+                                           break instead of trap. */
 #define MASK_PAIRED_SINGLE 0x10000000   /* Support paired-single FPU.  */
 #define MASK_MIPS3D        0x20000000   /* Support MIPS-3D instructions.  */
 
@@ -222,6 +223,7 @@ extern const struct mips_cpu_info *mips_tune_info;
 #define TARGET_4300_MUL_FIX     ((target_flags & MASK_4300_MUL_FIX) != 0)
 
 #define TARGET_CHECK_ZERO_DIV   ((target_flags & MASK_NO_CHECK_ZERO_DIV) == 0)
+#define TARGET_DIVIDE_TRAPS     ((target_flags & MASK_DIVIDE_BREAKS) == 0)
 
 #define TARGET_BRANCHLIKELY	((target_flags & MASK_BRANCHLIKELY) != 0)
 
@@ -632,6 +634,10 @@ extern const struct mips_cpu_info *mips_tune_info;
      N_("Trap on integer divide by zero")},				\
   {"no-check-zero-division", MASK_NO_CHECK_ZERO_DIV,			\
      N_("Don't trap on integer divide by zero")},			\
+  {"divide-traps", -MASK_DIVIDE_BREAKS,					\
+     N_("Use trap to check for integer divide by zero")},		\
+  {"divide-breaks", MASK_DIVIDE_BREAKS,					\
+     N_("Use break to check for integer divide by zero")},		\
   { "branch-likely",      MASK_BRANCHLIKELY,				\
       N_("Use Branch Likely instructions, overriding default for arch")}, \
   { "no-branch-likely",  -MASK_BRANCHLIKELY,				\
@@ -782,13 +788,19 @@ extern const struct mips_cpu_info *mips_tune_info;
    --with-tune is ignored if -mtune is specified.
    --with-abi is ignored if -mabi is specified.
    --with-float is ignored if -mhard-float or -msoft-float are
-     specified.  */
+     specified.
+   --with-divide is ignored if -mdivide-traps or -mdivide-breaks are
+     specified. */
 #define OPTION_DEFAULT_SPECS \
   {"arch", "%{!march=*:%{mips16:-march=%(VALUE)}%{!mips*:-march=%(VALUE)}}" }, \
   {"tune", "%{!mtune=*:-mtune=%(VALUE)}" }, \
   {"abi", "%{!mabi=*:-mabi=%(VALUE)}" }, \
-  {"float", "%{!msoft-float:%{!mhard-float:-m%(VALUE)-float}}" }
+  {"float", "%{!msoft-float:%{!mhard-float:-m%(VALUE)-float}}" }, \
+  {"divide", "%{!mdivide-traps:%{!mdivide-breaks:-mdivide-%(VALUE)}}" }
+
 
+#define GENERATE_DIVIDE_TRAPS (TARGET_DIVIDE_TRAPS \
+                               && ISA_HAS_COND_TRAP)
 
 #define GENERATE_BRANCHLIKELY   (TARGET_BRANCHLIKELY                    \
 				 && !TARGET_SR71K                       \
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index dfad815..01cbb47 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -959,6 +959,18 @@ options and for @option{-mhard-float} or @option{-msoft-float}.  As with
 @option{--with-cpu}, which switches will be accepted and acceptable values
 of the arguments depend on the target.
 
+@item --with-divide=@var{type}
+Specify how the compiler should generate code for checking for
+division by zero.  This option is only supported on the MIPS target.
+The possibilities for @var{type} are:
+@table @code
+@item traps
+Division by zero checks use conditional traps (this is the default on
+systems that support conditional traps).
+@item breaks
+Division by zero checks use the break instruction.
+@end table
+
 @item --enable-altivec
 Specify that the target supports AltiVec vector enhancements.  This
 option will adjust the ABI for AltiVec enhancements, as well as generate
@@ -3201,6 +3213,16 @@ configure for @samp{mipsel-elf} as a workaround.  The
 @samp{mips*-*-linux*} target continues to use the MIPS II routines.  More
 work on this is expected in future releases.
 
+MIPS systems check for division by zero (unless
+@option{-mno-check-zero-division} is passed to the compiler) by
+generating either a conditional trap or a break instruction.  Using
+trap results in smaller code, but is only supported on MIPS II and
+later.  Also, some versions of the Linux kernel have a bug that
+prevents trap from generating the proper signal (SIGFPE).  To enable
+the use of break, use the @option{--with-divide=breaks}
+@command{configure} option when configuring GCC.  The default is to
+use traps on systems that support them.
+
 Cross-compilers for the Mips as target using the Mips assembler
 currently do not work, because the auxiliary programs
 @file{mips-tdump.c} and @file{mips-tfile.c} can't be compiled on
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ea5f983..b757e26 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -545,6 +545,7 @@ Objective-C and Objective-C++ Dialects}.
 -msplit-addresses  -mno-split-addresses  @gol
 -mexplicit-relocs  -mno-explicit-relocs  @gol
 -mcheck-zero-division  -mno-check-zero-division @gol
+-mdivide-traps  -mdivide-breaks @gol
 -mmemcpy  -mno-memcpy  -mlong-calls  -mno-long-calls @gol
 -mmad  -mno-mad  -mfused-madd  -mno-fused-madd  -nocpp @gol
 -mfix-r4000  -mno-fix-r4000  -mfix-r4400  -mno-fix-r4400 @gol
@@ -9500,6 +9501,23 @@ to use an assembler that supports relocation operators.
 Trap (do not trap) on integer division by zero.  The default is
 @option{-mcheck-zero-division}.
 
+@item -mdivide-traps
+@itemx -mdivide-breaks
+@opindex mdivide-traps
+@opindex mdivide-breaks
+MIPS systems check for division by zero by generating either a
+conditional trap or a break instruction.  Using traps results in
+smaller code, but is only supported on MIPS II and later.  Also, some
+versions of the Linux kernel have a bug that prevents trap from
+generating the proper signal (SIGFPE).  Use @option{-mdivide-traps} to
+allow conditional traps on architectures that support them and
+@option{-mdivide-breaks} to force the use of breaks.
+
+The default is usually @option{-mdivide-traps}, but this can be
+overridden at configure time using @option{--with-divide=breaks}.
+Divide-by-zero checks can be completely disabled using
+@option{-mno-check-zero-division}.
+
 @item -mmemcpy
 @itemx -mno-memcpy
 @opindex mmemcpy