i386 fp compares fix

[Jan Hubicka <jh at suse dot cz>]

Hi
The gcc crashes quite mysteriously while compiling bb demo on refusing fp
comparison instructions created in rtl generation pass.  The problem is partly
in fp_jcc_? patterns, that should accept memory for CCFP mode comparison, but
they don't since compare code in the IF_THEN_ELSE is always VOIDmode, so I've
changed them to use SELECT_CC_MODE based test instead.

This didn't helped in the all cases, since SELECT_CC_MODE works bit differently
from the expanders, that does use ix86_fp_compare_mode.  The main difference is
that ix86_fp_compare_mode returns always CCFPmode in fast_math, but
SELECT_CC_MODE don't.  It seems to be correct to modify SELECT_CC_MODE to use
ix86_fp_compare_mode.

The ix86_fp_compare_mode works in strage way too, since it first computes
unordered and then does:
  /* ??? If we knew whether invalid-operand exceptions were masked,
     we could rely on fcom to raise an exception and take care of
     NaNs.  But we don't.  We could know this from c99 math pragmas.  */
  if (TARGET_IEEE_FP)
    unordered = 1;
So unordered is always 1 for non -ffast-math programs.  Isn't that somewhat
overactive?

Honza

Thu Mar 17 00:23:24 CET 2005  Jan Hubicka  <jh@suse.cz>
	* i386.md (jp_jcc_3, jp_jcc_4):  Use SELECT_CC_MODE instead
	of CCmode matcher.
	* i386.c (ix86_fp_compare_mode): Make global.
	* i386-protos.h (ix86_fp_compare_mode): Declare.
*** /c/egcs/gcc/config/i386/i386.md	Thu Sep  7 13:32:40 2000
--- i386.md	Mon Aug 16 12:42:45 2004
***************
*** 8125,8131 ****
  
  (define_insn "*fp_jcc_3"
    [(set (pc)
! 	(if_then_else (match_operator:CCFP 0 "comparison_operator"
  			[(match_operand 1 "register_operand" "f")
  			 (match_operand 2 "nonimmediate_operand" "fm")])
  	  (label_ref (match_operand 3 "" ""))
--- 8125,8131 ----
  
  (define_insn "*fp_jcc_3"
    [(set (pc)
! 	(if_then_else (match_operator 0 "comparison_operator"
  			[(match_operand 1 "register_operand" "f")
  			 (match_operand 2 "nonimmediate_operand" "fm")])
  	  (label_ref (match_operand 3 "" ""))
***************
*** 8136,8147 ****
    "TARGET_80387
     && (GET_MODE (operands[1]) == SFmode || GET_MODE (operands[1]) == DFmode)
     && GET_MODE (operands[1]) == GET_MODE (operands[2])
     && !ix86_use_fcomi_compare (GET_CODE (operands[0]))"
    "#")
  
  (define_insn "*fp_jcc_4"
    [(set (pc)
! 	(if_then_else (match_operator:CCFP 0 "comparison_operator"
  			[(match_operand 1 "register_operand" "f")
  			 (match_operand 2 "nonimmediate_operand" "fm")])
  	  (pc)
--- 8136,8149 ----
    "TARGET_80387
     && (GET_MODE (operands[1]) == SFmode || GET_MODE (operands[1]) == DFmode)
     && GET_MODE (operands[1]) == GET_MODE (operands[2])
+    && (SELECT_CC_MODE (GET_CODE (operands[0]), operands[1], operands[2])
+        == CCFPmode)
     && !ix86_use_fcomi_compare (GET_CODE (operands[0]))"
    "#")
  
  (define_insn "*fp_jcc_4"
    [(set (pc)
! 	(if_then_else (match_operator 0 "comparison_operator"
  			[(match_operand 1 "register_operand" "f")
  			 (match_operand 2 "nonimmediate_operand" "fm")])
  	  (pc)
***************
*** 8152,8157 ****
--- 8154,8161 ----
    "TARGET_80387
     && (GET_MODE (operands[1]) == SFmode || GET_MODE (operands[1]) == DFmode)
     && GET_MODE (operands[1]) == GET_MODE (operands[2])
+    && (SELECT_CC_MODE (GET_CODE (operands[0]), operands[1], operands[2])
+        == CCFPmode)
     && !ix86_use_fcomi_compare (GET_CODE (operands[0]))"
    "#")
  
*** /c/egcs/gcc/config/i386/i386.c	Tue Aug 29 14:04:10 2000
--- i386.c	Mon Aug 16 13:04:21 2004
*************** static void put_condition_code PARAMS ((
*** 390,396 ****
  				       int, int, FILE *));
  static enum rtx_code unsigned_comparison PARAMS ((enum rtx_code code));
  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 gen_push PARAMS ((rtx));
--- 390,395 ----
*************** ix86_expand_int_compare (code, op0, op1)
*** 4574,4580 ****
  /* Figure out whether to use ordered or unordered fp comparisons.
     Return the appropriate mode to use.  */
  
! static enum machine_mode
  ix86_fp_compare_mode (code)
       enum rtx_code code;
  {
--- 4573,4579 ----
  /* Figure out whether to use ordered or unordered fp comparisons.
     Return the appropriate mode to use.  */
  
! enum machine_mode
  ix86_fp_compare_mode (code)
       enum rtx_code code;
  {
*** /c/egcs/gcc/config/i386/i386-protos.h	Tue Aug 29 14:04:08 2000
--- i386-protos.h	Mon Aug 16 13:03:26 2004
*************** extern int ix86_adjust_cost PARAMS ((rtx
*** 123,128 ****
--- 123,129 ----
  extern void ix86_sched_init PARAMS ((FILE *, int));
  extern int ix86_sched_reorder PARAMS ((FILE *, int, rtx *, int, int));
  extern int ix86_variable_issue PARAMS ((FILE *, int, rtx, int));
+ extern enum machine_mode ix86_fp_compare_mode PARAMS ((enum rtx_code));
  
  #ifdef TREE_CODE
  extern void init_cumulative_args PARAMS ((CUMULATIVE_ARGS *, tree, rtx));
*** /c/egcs/gcc/config/i386/i386.h	Thu Sep  7 13:32:28 2000
--- i386.h	Mon Aug 16 13:03:01 2004
*************** while (0)
*** 2281,2287 ****
  
  #define SELECT_CC_MODE(OP,X,Y)				\
    (GET_MODE_CLASS (GET_MODE (X)) == MODE_FLOAT		\
!    ? (OP) == EQ || (OP) == NE ? CCFPUmode : CCFPmode	\
     : (OP) == LE || (OP) == GT ? CCmode			\
     : (Y) != const0_rtx ? CCmode				\
     : (OP) == EQ || (OP) == NE ? CCZmode : CCNOmode)
--- 2281,2287 ----
  
  #define SELECT_CC_MODE(OP,X,Y)				\
    (GET_MODE_CLASS (GET_MODE (X)) == MODE_FLOAT		\
!    ? ix86_fp_compare_mode (OP)				\
     : (OP) == LE || (OP) == GT ? CCmode			\
     : (Y) != const0_rtx ? CCmode				\
     : (OP) == EQ || (OP) == NE ? CCZmode : CCNOmode)