On Thu, 26 Apr 2012, Richard Guenther wrote:
On Wed, Apr 25, 2012 at 3:58 PM, Marc Glisse <marc.gli...@inria.fr> wrote:
Here is take 2 on this patch, which seems cleaner. Bootstrapped and
regression tested.
gcc/ChangeLog
2012-04-25 Marc Glisse <marc.gli...@inria.fr>
PR middle-end/27139
* tree-ssa-forwprop.c (combine_conversions): Handle INT->FP->INT.
gcc/testsuite/ChangeLog
2012-04-25 Marc Glisse <marc.gli...@inria.fr>
PR middle-end/27139
* gcc.dg/tree-ssa/forwprop-18.c: New test.
In my patch, the lines with gimple_assign_* are vaguely guessed from what is
around, I don't pretend to understand them.
;)
The patch looks good to me - on a 2nd thought folding the case back in
to the if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))
block to benefit from the local vars therein makes sense (but as separate
sub-if () as it is now).
Like the attached? (c,c++ bootstrapped, make -k check, no regression)
I changed the types in the testcase to make it really unlikely that a
platform needs to skip it (it would require a long double that can't
represent all signed char, or a float that can represent all unsigned long
long).
--
Marc Glisse
Index: testsuite/gcc.dg/tree-ssa/forwprop-18.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/forwprop-18.c (revision 0)
+++ testsuite/gcc.dg/tree-ssa/forwprop-18.c (revision 0)
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-forwprop1" } */
+
+signed char f1(signed char n)
+{
+ return (long double)n;
+}
+unsigned long long f2(signed char n)
+{
+ return (long double)n;
+}
+
+unsigned long long g1(unsigned long long n)
+{
+ return (float)n;
+}
+signed char g2(unsigned long long n)
+{
+ return (float)n;
+}
+
+/* { dg-final { scan-tree-dump-times "\\\(float\\\)" 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-not "\\\(long double\\\)" "forwprop1" } } */
+/* { dg-final { cleanup-tree-dump "forwprop1" } } */
Property changes on: testsuite/gcc.dg/tree-ssa/forwprop-18.c
___________________________________________________________________
Added: svn:keywords
+ Author Date Id Revision URL
Added: svn:eol-style
+ native
Index: tree-ssa-forwprop.c
===================================================================
--- tree-ssa-forwprop.c (revision 186876)
+++ tree-ssa-forwprop.c (working copy)
@@ -2403,10 +2403,11 @@ combine_conversions (gimple_stmt_iterato
{
gimple stmt = gsi_stmt (*gsi);
gimple def_stmt;
tree op0, lhs;
enum tree_code code = gimple_assign_rhs_code (stmt);
+ enum tree_code code2;
gcc_checking_assert (CONVERT_EXPR_CODE_P (code)
|| code == FLOAT_EXPR
|| code == FIX_TRUNC_EXPR);
@@ -2423,11 +2424,13 @@ combine_conversions (gimple_stmt_iterato
def_stmt = SSA_NAME_DEF_STMT (op0);
if (!is_gimple_assign (def_stmt))
return 0;
- if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))
+ code2 = gimple_assign_rhs_code (def_stmt);
+
+ if (CONVERT_EXPR_CODE_P (code2) || code2 == FLOAT_EXPR)
{
tree defop0 = gimple_assign_rhs1 (def_stmt);
tree type = TREE_TYPE (lhs);
tree inside_type = TREE_TYPE (defop0);
tree inter_type = TREE_TYPE (op0);
@@ -2551,10 +2554,33 @@ combine_conversions (gimple_stmt_iterato
else
gimple_assign_set_rhs_from_tree (gsi, tem);
update_stmt (gsi_stmt (*gsi));
return 1;
}
+
+ /* If we are converting an integer to a floating-point that can
+ represent it exactly and back to an integer, we can skip the
+ floating-point conversion. */
+ if (inside_int && inter_float && final_int &&
+ (unsigned) significand_size (TYPE_MODE (inter_type))
+ >= inside_prec - !inside_unsignedp)
+ {
+ if (useless_type_conversion_p (type, inside_type))
+ {
+ gimple_assign_set_rhs1 (stmt, unshare_expr (defop0));
+ gimple_assign_set_rhs_code (stmt, TREE_CODE (defop0));
+ update_stmt (stmt);
+ return remove_prop_source_from_use (op0) ? 2 : 1;
+ }
+ else
+ {
+ gimple_assign_set_rhs1 (stmt, defop0);
+ gimple_assign_set_rhs_code (stmt, CONVERT_EXPR);
+ update_stmt (stmt);
+ return remove_prop_source_from_use (op0) ? 2 : 1;
+ }
+ }
}
return 0;
}
