i386-protos.h (ix86_expand_compare): Add extern decl.

	* config/i386/i386-protos.h (ix86_expand_compare): Add extern decl.
	* config/i386/i386.c (ix86_expand_compare): Remove `static'.
	* config/i386/i386.md (trap, conditional_trap): New insn & expand.

From-SVN: r36019

gcc/ChangeLog

+2000-08-28  Greg McGary  <greg@mcgary.org>
+
+	* config/i386/i386-protos.h (ix86_expand_compare): Add extern decl.
+	* config/i386/i386.c (ix86_expand_compare): Remove `static'.
+	* config/i386/i386.md (trap, conditional_trap): New insn & expand.
+
 2000-08-27  Greg McGary  <greg@mcgary.org>
 
 	* cpplex.c (parse_string): Don't look for backslash

gcc/config/i386/i386-protos.h

@@ -100,6 +100,7 @@ extern int ix86_unary_operator_ok PARAMS ((enum rtx_code, enum machine_mode,
 					 rtx[]));
 extern int ix86_match_ccmode PARAMS ((rtx, enum machine_mode));
 extern rtx ix86_expand_fp_compare PARAMS ((enum rtx_code, rtx, rtx, rtx));
+extern rtx ix86_expand_compare PARAMS ((enum rtx_code));
 extern int ix86_use_fcomi_compare PARAMS ((enum rtx_code));
 extern void ix86_expand_branch PARAMS ((enum rtx_code, rtx));
 extern int ix86_expand_setcc PARAMS ((enum rtx_code, rtx));

gcc/config/i386/i386.c

@@ -402,7 +402,6 @@ static rtx ix86_expand_int_compare PARAMS ((enum rtx_code, rtx, rtx));
 static enum machine_mode ix86_fp_compare_mode PARAMS ((enum rtx_code));
 static enum rtx_code ix86_prepare_fp_compare_args PARAMS ((enum rtx_code,
 							   rtx *, rtx *));
-static rtx ix86_expand_compare PARAMS ((enum rtx_code));
 static rtx gen_push PARAMS ((rtx));
 static int memory_address_length PARAMS ((rtx addr));
 static int ix86_flags_dependant PARAMS ((rtx, rtx, enum attr_type));
@@ -4897,7 +4896,7 @@ ix86_expand_fp_compare (code, op0, op1, scratch)
 			 const0_rtx);
 }
 
-static rtx
+rtx
 ix86_expand_compare (code)
      enum rtx_code code;
 {

gcc/config/i386/i386.md

@@ -11129,3 +11129,52 @@
     return \"call\\t%*%1\";
 }"
   [(set_attr "type" "callv")])
+
+(define_insn "trap"
+  [(trap_if (const_int 1) (const_int 5))]
+  ""
+  "int\\t$5")
+
+;;; ix86 doesn't have conditional trap instructions, but we fake them
+;;; for the sake of bounds checking.  By emitting bounds checks as
+;;; conditional traps rather than as conditional jumps around
+;;; unconditional traps we avoid introducing spurious basic-block
+;;; boundaries and facilitate elimination of redundant checks.  In
+;;; honor of the too-inflexible-for-BPs `bound' instruction, we use
+;;; interrupt 5.
+;;; 
+;;; FIXME: Static branch prediction rules for ix86 are such that
+;;; forward conditional branches predict as untaken.  As implemented
+;;; below, pseudo conditional traps violate that rule.  We should use
+;;; .pushsection/.popsection to place all of the `int 5's in a special
+;;; section loaded at the end of the text segment and branch forward
+;;; there on bounds-failure, and then jump back immediately (in case
+;;; the system chooses to ignore bounds violations, or to report
+;;; violations and continue execution).
+
+(define_expand "conditional_trap"
+  [(trap_if (match_operator 0 "comparison_operator"
+	     [(match_dup 2) (const_int 0)])
+	    (match_operand 1 "const_int_operand" ""))]
+  ""
+  "
+{
+  emit_insn (gen_rtx_TRAP_IF (VOIDmode,
+			      ix86_expand_compare (GET_CODE (operands[0])),
+			      operands[1]));
+  DONE;
+}")
+
+(define_insn ""
+  [(trap_if (match_operator 0 "comparison_operator"
+	     [(reg 17) (const_int 0)])
+	    (match_operand 1 "const_int_operand" ""))]
+  ""
+  "*
+{
+  operands[2] = gen_label_rtx ();
+  output_asm_insn (\"j%c0\\t%l2\; int\\t%1\", operands);
+  ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, \"L\",
+			     CODE_LABEL_NUMBER (operands[2]));
+  RET;
+}")