On Fri, 22 Jul 2011, Richard Guenther wrote:

> On Thu, 21 Jul 2011, Joseph S. Myers wrote:
> 
> > On Thu, 21 Jul 2011, Richard Guenther wrote:
> > 
> > > Patch also handling wider modes and not starting with SImode but
> > > the mode of int:
> > 
> > Use of target int for anything not about C ABIs is certainly wrong.  This 
> > might be about what operations the target does efficiently, or what 
> > functions are present in libgcc (both of which would be functions of 
> > machine modes), but it's not about the choice of C int.
> 
> Ok.  Given rths last suggestion I'm testing the following which
> checks all integer modes (but never will widen - optabs.c will do
> that if it turns out to be profitable).

Err, I should refresh the patch before sending it ... here it goes.

Richard.

2011-07-22  Richard Guenther  <rguent...@suse.de>

        PR tree-optimization/49715
        * tree-vrp.c: Include expr.h and optabs.h.
        (simplify_float_conversion_using_ranges): New function.
        (simplify_stmt_using_ranges): Call it.
        * Makefile.in (tree-vrp.o): Add $(EXPR_H) and $(OPTABS_H) dependencies.
        * optabs.c (can_float_p): Export.
        * optabs.h (can_float_p): Declare.

        * gcc.target/i386/pr49715-1.c: New testcase.
        * gcc.target/i386/pr49715-2.c: Likewise.

Index: gcc/tree-vrp.c
===================================================================
*** gcc/tree-vrp.c.orig 2011-07-21 17:46:16.000000000 +0200
--- gcc/tree-vrp.c      2011-07-22 11:09:03.000000000 +0200
*************** along with GCC; see the file COPYING3.
*** 40,45 ****
--- 40,47 ----
  #include "tree-ssa-propagate.h"
  #include "tree-chrec.h"
  #include "gimple-fold.h"
+ #include "expr.h"
+ #include "optabs.h"
  
  
  /* Type of value ranges.  See value_range_d for a description of these
*************** simplify_conversion_using_ranges (gimple
*** 7448,7453 ****
--- 7450,7520 ----
    return true;
  }
  
+ /* Simplify a conversion from integral SSA name to float in STMT.  */
+ 
+ static bool
+ simplify_float_conversion_using_ranges (gimple_stmt_iterator *gsi, gimple 
stmt)
+ {
+   tree rhs1 = gimple_assign_rhs1 (stmt);
+   value_range_t *vr = get_value_range (rhs1);
+   enum machine_mode fltmode = TYPE_MODE (TREE_TYPE (gimple_assign_lhs 
(stmt)));
+   enum machine_mode mode;
+   tree tem;
+   gimple conv;
+ 
+   /* We can only handle constant ranges.  */
+   if (vr->type != VR_RANGE
+       || TREE_CODE (vr->min) != INTEGER_CST
+       || TREE_CODE (vr->max) != INTEGER_CST)
+     return false;
+ 
+   /* Search for a mode we can use.  */
+   mode = GET_CLASS_NARROWEST_MODE (MODE_INT);
+   do
+     {
+       double_int tem;
+ 
+       /* If we cannot do a signed conversion to float from mode
+        or if the value-range does not fit in the signed type
+        try with a wider mode.  */
+       if (can_float_p (fltmode, mode, 0) != CODE_FOR_nothing)
+       {
+         tem = double_int_ext (tree_to_double_int (vr->min),
+                               GET_MODE_PRECISION (mode), 0);
+         if (double_int_equal_p (tree_to_double_int (vr->min), tem))
+           {
+             tem = double_int_ext (tree_to_double_int (vr->max),
+                                   GET_MODE_PRECISION (mode), 0);
+             if (double_int_equal_p (tree_to_double_int (vr->max), tem))
+               break;
+           }
+       }
+ 
+       mode = GET_MODE_WIDER_MODE (mode);
+       /* But do not widen the input.  Instead leave that to the
+          optabs expansion code.  */
+       if (GET_MODE_PRECISION (mode) > TYPE_PRECISION (TREE_TYPE (rhs1)))
+       return false;
+     }
+   while (mode != VOIDmode);
+ 
+   if (mode == VOIDmode)
+     return false;
+ 
+   /* It works, insert a truncation or sign-change before the
+      float conversion.  */
+   tem = create_tmp_var (build_nonstandard_integer_type
+                         (GET_MODE_PRECISION (mode), 0), NULL);
+   conv = gimple_build_assign_with_ops (NOP_EXPR, tem, rhs1, NULL_TREE);
+   tem = make_ssa_name (tem, conv);
+   gimple_assign_set_lhs (conv, tem);
+   gsi_insert_before (gsi, conv, GSI_SAME_STMT);
+   gimple_assign_set_rhs1 (stmt, tem);
+   update_stmt (stmt);
+ 
+   return true;
+ }
+ 
  /* Simplify STMT using ranges if possible.  */
  
  static bool
*************** simplify_stmt_using_ranges (gimple_stmt_
*** 7507,7512 ****
--- 7574,7585 ----
            return simplify_conversion_using_ranges (stmt);
          break;
  
+       case FLOAT_EXPR:
+         if (TREE_CODE (rhs1) == SSA_NAME
+             && INTEGRAL_TYPE_P (TREE_TYPE (rhs1)))
+           return simplify_float_conversion_using_ranges (gsi, stmt);
+         break;
+ 
        default:
          break;
        }
Index: gcc/testsuite/gcc.target/i386/pr49715-1.c
===================================================================
*** /dev/null   1970-01-01 00:00:00.000000000 +0000
--- gcc/testsuite/gcc.target/i386/pr49715-1.c   2011-07-21 17:46:39.000000000 
+0200
***************
*** 0 ****
--- 1,9 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O2 -msse -mfpmath=sse" } */
+ 
+ float func(unsigned x)
+ {
+   return (x & 0xfffff) * 0.01f;
+ }
+ 
+ /* { dg-final { scan-assembler-times "cvtsi2ss" 1 } } */
Index: gcc/testsuite/gcc.target/i386/pr49715-2.c
===================================================================
*** /dev/null   1970-01-01 00:00:00.000000000 +0000
--- gcc/testsuite/gcc.target/i386/pr49715-2.c   2011-07-21 17:46:39.000000000 
+0200
***************
*** 0 ****
--- 1,12 ----
+ /* { dg-do compile } */
+ /* { dg-require-effective-target lp64 } */
+ /* { dg-options "-O2" } */
+ 
+ double func(unsigned long long x)
+ {
+   if (x <= 0x7ffffffffffffffeULL)
+     return (x + 1) * 0.01;
+   return 0.0;
+ }
+ 
+ /* { dg-final { scan-assembler-times "cvtsi2sdq" 1 } } */
Index: gcc/Makefile.in
===================================================================
*** gcc/Makefile.in.orig        2011-07-19 12:59:09.000000000 +0200
--- gcc/Makefile.in     2011-07-22 11:09:16.000000000 +0200
*************** tree-vrp.o : tree-vrp.c $(CONFIG_H) $(SY
*** 2504,2510 ****
     $(TREE_FLOW_H) $(TREE_PASS_H) $(TREE_DUMP_H) $(DIAGNOSTIC_H) $(GGC_H) \
     $(BASIC_BLOCK_H) tree-ssa-propagate.h $(FLAGS_H) $(TREE_DUMP_H) \
     $(CFGLOOP_H) $(SCEV_H) $(TIMEVAR_H) intl.h tree-pretty-print.h \
!    gimple-pretty-print.h gimple-fold.h
  tree-cfg.o : tree-cfg.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
     $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(FLAGS_H) output.h \
     $(DIAGNOSTIC_H) $(FUNCTION_H) $(TIMEVAR_H) $(TM_H) coretypes.h \
--- 2504,2510 ----
     $(TREE_FLOW_H) $(TREE_PASS_H) $(TREE_DUMP_H) $(DIAGNOSTIC_H) $(GGC_H) \
     $(BASIC_BLOCK_H) tree-ssa-propagate.h $(FLAGS_H) $(TREE_DUMP_H) \
     $(CFGLOOP_H) $(SCEV_H) $(TIMEVAR_H) intl.h tree-pretty-print.h \
!    gimple-pretty-print.h gimple-fold.h $(OPTABS_H) $(EXPR_H)
  tree-cfg.o : tree-cfg.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
     $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(FLAGS_H) output.h \
     $(DIAGNOSTIC_H) $(FUNCTION_H) $(TIMEVAR_H) $(TM_H) coretypes.h \
Index: gcc/optabs.c
===================================================================
*** gcc/optabs.c.orig   2011-07-11 17:02:51.000000000 +0200
--- gcc/optabs.c        2011-07-22 11:04:42.000000000 +0200
*************** can_fix_p (enum machine_mode fixmode, en
*** 4626,4632 ****
    return CODE_FOR_nothing;
  }
  
! static enum insn_code
  can_float_p (enum machine_mode fltmode, enum machine_mode fixmode,
             int unsignedp)
  {
--- 4626,4632 ----
    return CODE_FOR_nothing;
  }
  
! enum insn_code
  can_float_p (enum machine_mode fltmode, enum machine_mode fixmode,
             int unsignedp)
  {
Index: gcc/optabs.h
===================================================================
*** gcc/optabs.h.orig   2011-06-22 16:01:28.000000000 +0200
--- gcc/optabs.h        2011-07-22 11:06:01.000000000 +0200
*************** extern void expand_fixed_convert (rtx, r
*** 849,854 ****
--- 849,857 ----
  /* Generate code for a FLOAT_EXPR.  */
  extern void expand_float (rtx, rtx, int);
  
+ /* Return the insn_code for a FLOAT_EXPR.  */
+ enum insn_code can_float_p (enum machine_mode, enum machine_mode, int);
+ 
  /* Generate code for a FIX_EXPR.  */
  extern void expand_fix (rtx, rtx, int);
  

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