On Thu, Oct 6, 2011 at 4:25 PM, Kai Tietz <kti...@redhat.com> wrote:
> Hi,
>
> I modified the patch so, that it always just converts two leafs of a
> TRUTH(AND|OR)IF chain into a TRUTH_(AND|OR) expression, if branch costs are
> high and leafs are simple without side-effects.
>
> Additionally I added some testcases for it.
>
> 2011-10-06 Kai Tietz <kti...@redhat.com>
>
> * fold-const.c (fold_truth_andor): Convert TRUTH_(AND|OR)IF_EXPR
> to TRUTH_OR_EXPR, if suitable.
>
> 2011-10-06 Kai Tietz <kti...@redhat.com>
>
> * gcc.dg/tree-ssa/ssa-ifbranch-1.c: New test.
> * gcc.dg/tree-ssa/ssa-ifbranch-2.c: New test.
> * gcc.dg/tree-ssa/ssa-ifbranch-3.c: New test.
> * gcc.dg/tree-ssa/ssa-ifbranch-4.c: New test.
>
> Bootstrapped and tested for all languages (including Ada and Obj-C++) on host
> x86_64-unknown-linux-gnu. Ok for apply?
>
> Regards,
> Kai
>
> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-1.c
> ===================================================================
> --- /dev/null
> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-1.c
> @@ -0,0 +1,18 @@
> +/* Skip on MIPS, S/390, and AVR due LOGICAL_OP_NON_SHORT_CIRCUIT, and
> + lower values in BRANCH_COST. */
> +/* { dg-do compile { target { ! "mips*-*-* s390*-*-* avr-*-* mn10300-*-*" }
> } } */
> +/* { dg-options "-O2 -fdump-tree-gimple" } */
> +/* { dg-options "-O2 -fdump-tree-gimple -march=i586" { target { i?86-*-* &&
> ilp32 } } } */
> +
> +extern int doo1 (void);
> +extern int doo2 (void);
> +
> +int bar (int a, int b, int c)
> +{
> + if (a && b && c)
> + return doo1 ();
> + return doo2 ();
> +}
> +
> +/* { dg-final { scan-tree-dump-times "if " 2 "gimple" } } */
> +/* { dg-final { cleanup-tree-dump "gimple" } } */
> Index: gcc-head/gcc/fold-const.c
> ===================================================================
> --- gcc-head.orig/gcc/fold-const.c
> +++ gcc-head/gcc/fold-const.c
> @@ -8387,6 +8387,45 @@ fold_truth_andor (location_t loc, enum t
> if ((tem = fold_truthop (loc, code, type, arg0, arg1)) != 0)
> return tem;
>
> + if ((code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
> + && !TREE_SIDE_EFFECTS (arg1)
> + && LOGICAL_OP_NON_SHORT_CIRCUIT
> + /* floats might trap. */
> + && !FLOAT_TYPE_P (TREE_TYPE (arg1))
Floats don't "trap" on their own. If possibly trapping trees don't have
TREE_SIDE_EFFECTS set then you want
&& !tree_could_trap_p (arg1)
here.
> + && ((TREE_CODE_CLASS (TREE_CODE (arg1)) != tcc_comparison
> + && TREE_CODE (arg1) != TRUTH_NOT_EXPR
> + && simple_operand_p (arg1))
As I said previously simple_operand_p already rejects covers
comparisons and TRUTH_NOT_EXPR. Also arg1 had better
TREE_SIDE_EFFECTS set if the comparison might trap, as
it might just be hidden in something more complicated - so
the simple check isn't enough anyway (and if simple_operand_p
would cover it, the check would be better placed there).
> + || ((TREE_CODE_CLASS (TREE_CODE (arg1)) == tcc_comparison
> + || TREE_CODE (arg1) == TRUTH_NOT_EXPR)
> + /* Float comparison might trap. */
> + && !FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0)))
> + && simple_operand_p (TREE_OPERAND (arg1, 0)))))
> + {
> + /* We want to combine truth-comparison for
> + ((W TRUTH-ANDOR X) TRUTH-ANDORIF Y) TRUTH-ANDORIF Z,
> + if Y and Z are simple operands and have no side-effect to
> + ((W TRUTH-ANDOR X) TRUTH-IF (Y TRUTH-ANDOR Z). */
No we don't. See down-thread.
> + if (TREE_CODE (arg0) == code
> + && !TREE_SIDE_EFFECTS (TREE_OPERAND (arg0, 1))
> + && simple_operand_p (TREE_OPERAND (arg0, 1)))
> + {
> + tem = build2_loc (loc,
> + (code == TRUTH_ANDIF_EXPR ? TRUTH_AND_EXPR
> + : TRUTH_OR_EXPR),
> + type, TREE_OPERAND (arg0, 1), arg1);
> + return build2_loc (loc, code, type, TREE_OPERAND (arg0, 0),
> + tem);
All trees should be folded, don't use plain build without a good reason.
> + }
> + /* Convert X TRUTH-ANDORIF Y to X TRUTH-ANDOR Y, if X and Y
> + are simple operands and have no side-effects. */
> + if (simple_operand_p (arg0)
> + && !TREE_SIDE_EFFECTS (arg0))
Again, the checks you do for arg0 do not match those for arg1. OTOH
it doesn't matter whether arg0 is simple or not or has side-effects or
not for this transformation, so why check it at all?
In fold_truthop we still have the same (albeit more restricted transform),
but guarded with
if (BRANCH_COST (optimize_function_for_speed_p (cfun),
false) >= 2
too. Why not here? Please delete redundant code in fold_truthop.
It's also odd that this is only called from fold_truth_andor but has
a more generic name, so maybe rename it to fold_truth_andor_1 on the way.
Richard.
> + return build2_loc (loc,
> + (code == TRUTH_ANDIF_EXPR ? TRUTH_AND_EXPR
> + : TRUTH_OR_EXPR),
> + type, arg0, arg1);
> + }
> +
> return NULL_TREE;
> }
>
> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-2.c
> ===================================================================
> --- /dev/null
> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-2.c
> @@ -0,0 +1,18 @@
> +/* Skip on MIPS, S/390, and AVR due LOGICAL_OP_NON_SHORT_CIRCUIT, and
> + lower values in BRANCH_COST. */
> +/* { dg-do compile { target { ! "mips*-*-* s390*-*-* avr-*-* mn10300-*-*" }
> } } */
> +/* { dg-options "-O2 -fdump-tree-gimple" } */
> +/* { dg-options "-O2 -fdump-tree-gimple -march=i586" { target { i?86-*-* &&
> ilp32 } } } */
> +
> +extern int doo1 (void);
> +extern int doo2 (void);
> +
> +int bar (int a, int b, int c, int d)
> +{
> + if (a && b && c && d)
> + return doo1 ();
> + return doo2 ();
> +}
> +
> +/* { dg-final { scan-tree-dump-times "if " 2 "gimple" } } */
> +/* { dg-final { cleanup-tree-dump "gimple" } } */
> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-3.c
> ===================================================================
> --- /dev/null
> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-3.c
> @@ -0,0 +1,18 @@
> +/* Skip on MIPS, S/390, and AVR due LOGICAL_OP_NON_SHORT_CIRCUIT, and
> + lower values in BRANCH_COST. */
> +/* { dg-do compile { target { ! "mips*-*-* s390*-*-* avr-*-* mn10300-*-*" }
> } } */
> +/* { dg-options "-O2 -fdump-tree-gimple" } */
> +/* { dg-options "-O2 -fdump-tree-gimple -march=i586" { target { i?86-*-* &&
> ilp32 } } } */
> +
> +extern int doo1 (void);
> +extern int doo2 (void);
> +
> +int bar (int a, int c)
> +{
> + if (a && c)
> + return doo1 ();
> + return doo2 ();
> +}
> +
> +/* { dg-final { scan-tree-dump-times "if " 1 "gimple" } } */
> +/* { dg-final { cleanup-tree-dump "gimple" } } */
> Index: gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-4.c
> ===================================================================
> --- /dev/null
> +++ gcc-head/gcc/testsuite/gcc.dg/tree-ssa/ssa-ifbranch-4.c
> @@ -0,0 +1,18 @@
> +/* Skip on MIPS, S/390, and AVR due LOGICAL_OP_NON_SHORT_CIRCUIT, and
> + lower values in BRANCH_COST. */
> +/* { dg-do compile { target { ! "mips*-*-* s390*-*-* avr-*-* mn10300-*-*" }
> } } */
> +/* { dg-options "-O2 -fdump-tree-gimple" } */
> +/* { dg-options "-O2 -fdump-tree-gimple -march=i586" { target { i?86-*-* &&
> ilp32 } } } */
> +
> +extern int doo1 (void);
> +extern int doo2 (void);
> +
> +int bar (int a, int b, int c, int d)
> +{
> + if ((a && b) && (c && d))
> + return doo1 ();
> + return doo2 ();
> +}
> +
> +/* { dg-final { scan-tree-dump-times "if " 2 "gimple" } } */
> +/* { dg-final { cleanup-tree-dump "gimple" } } */
>
