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[PATCH] Introduce fortran loop preheader
- From: Martin LiÅka <mliska at suse dot cz>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Jan Hubicka <hubicka at ucw dot cz>
- Date: Thu, 16 Jun 2016 18:05:29 +0200
- Subject: [PATCH] Introduce fortran loop preheader
- Authentication-results: sourceware.org; auth=none
Hello.
Following patch introduces FORTRAN_LOOP_PREHEADER predictor for all
Fortran loops that are transformed to:
[Evaluate loop bounds and step]
dovar = from;
if ((step > 0) ? (dovar <= to) : (dovar => to))
{
for (;;)
{
body;
cycle_label:
cond = (dovar == to);
dovar += step;
if (cond) goto end_label;
}
}
end_label:
The first condition can be predicted as satisfied in most situations.
I've also measured the predictor on SPEC2006 and was 99%, which I've
picked up as the hitrate. The patch is pre-approved by Honza.
Patch survives reg&bootstrap on x86_64-linux-gnu.
Installed as r237533.
Martin
>From 6072b4e4a215b876da99ebb37132852bdfd033ee Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Wed, 15 Jun 2016 14:45:12 +0200
Subject: [PATCH 2/2] Introduce fortran loop preheader
gcc/ChangeLog:
2016-06-15 Martin Liska <mliska@suse.cz>
* predict.def: Add fortran loop preheader predictor.
* gimple-fold.c (gimple_fold_stmt_to_constant_1): Properly
fold IFN_BUILTIN_EXPECT with a known constant argument.
gcc/fortran/ChangeLog:
2016-06-15 Martin Liska <mliska@suse.cz>
* trans-stmt.c (gfc_trans_simple_do): Predict the edge.
gcc/testsuite/ChangeLog:
2016-06-16 Martin Liska <mliska@suse.cz>
* gfortran.dg/predict-1.f90: New test.
---
gcc/fortran/trans-stmt.c | 4 +++-
gcc/gimple-fold.c | 8 ++++++++
gcc/predict.def | 6 ++++++
gcc/testsuite/gfortran.dg/predict-1.f90 | 12 ++++++++++++
4 files changed, 29 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gfortran.dg/predict-1.f90
diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index 7d3cf8c..84bf749 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -1938,7 +1938,9 @@ gfc_trans_simple_do (gfc_code * code, stmtblock_t *pblock, tree dovar,
else
cond = fold_build2_loc (loc, GE_EXPR, boolean_type_node, dovar,
to);
- tmp = fold_build3_loc (loc, COND_EXPR, void_type_node, cond, tmp,
+
+ tmp = fold_build3_loc (loc, COND_EXPR, void_type_node,
+ gfc_likely (cond, PRED_FORTRAN_LOOP_PREHEADER), tmp,
build_empty_stmt (loc));
gfc_add_expr_to_block (pblock, tmp);
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 885367e..fa03e89 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -5250,6 +5250,14 @@ gimple_fold_stmt_to_constant_1 (gimple *stmt, tree (*valueize) (tree),
case IFN_UBSAN_CHECK_MUL:
subcode = MULT_EXPR;
break;
+ case IFN_BUILTIN_EXPECT:
+ {
+ tree arg0 = gimple_call_arg (stmt, 0);
+ tree op0 = (*valueize) (arg0);
+ if (TREE_CODE (op0) == INTEGER_CST)
+ return op0;
+ return NULL_TREE;
+ }
default:
return NULL_TREE;
}
diff --git a/gcc/predict.def b/gcc/predict.def
index 3e3a43a..a0d0ba9 100644
--- a/gcc/predict.def
+++ b/gcc/predict.def
@@ -199,3 +199,9 @@ DEF_PREDICTOR (PRED_FORTRAN_INVALID_BOUND, "Fortran invalid bound", \
which in turn has an optional argument. */
DEF_PREDICTOR (PRED_FORTRAN_ABSENT_DUMMY, "Fortran absent dummy", \
HITRATE (60), 0)
+
+/* Fortran DO statement generates a pre-header guard:
+ empty = (step > 0 ? to < from : to > from), which can be predicted
+ to be very likely. */
+DEF_PREDICTOR (PRED_FORTRAN_LOOP_PREHEADER, "Fortran loop preheader", \
+ HITRATE (99), 0)
diff --git a/gcc/testsuite/gfortran.dg/predict-1.f90 b/gcc/testsuite/gfortran.dg/predict-1.f90
new file mode 100644
index 0000000..81f0436
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/predict-1.f90
@@ -0,0 +1,12 @@
+! { dg-do compile }
+! { dg-options "-O2 -fdump-tree-profile_estimate" }
+
+subroutine test(block, array)
+integer :: i, block(9), array(2)
+
+do i = array(1), array(2)
+ block(i) = i
+end do
+end subroutine test
+
+! { dg-final { scan-tree-dump-times "Fortran loop preheader heuristics of edge\[^:\]*: 99.0%" 1 "profile_estimate" } }
--
2.8.3