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[PATCH] Fix PR47271: only if-convert full writes.
- From: Sebastian Pop <sebpop at gmail dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: rguenther at suse dot de, jakub at redhat dot com, Sebastian Pop <sebpop at gmail dot com>
- Date: Mon, 24 Jan 2011 14:31:24 -0600
- Subject: [PATCH] Fix PR47271: only if-convert full writes.
Hi,
The following patch filters out before if-conversion all the loops
containing basic blocks with more than 2 predecessors or containing
basic blocks that have exactly 2 predecessors not post-dominated by
the basic block: these basic blocks may contain phi nodes that are not
full writes. The current code generation for the tree-if-conversion
does not handle these cases.
I am regstrapping this patch on amd64-linux. Ok for trunk?
Thanks,
Sebastian
2011-01-24 Sebastian Pop <sebastian.pop@amd.com>
Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/47271
* tree-if-conv.c (bb_postdominates_preds): New.
(if_convertible_bb_p): Return false when bb has more than 2
predecessors. Call bb_postdominates_preds.
(if_convertible_loop_p_1): Compute CDI_POST_DOMINATORS.
(predicate_scalar_phi): Call bb_postdominates_preds.
* gcc.dg/tree-ssa/ifc-pr47271.c: New.
---
gcc/ChangeLog | 10 +++++
gcc/testsuite/ChangeLog | 6 +++
gcc/testsuite/gcc.dg/tree-ssa/ifc-pr47271.c | 49 +++++++++++++++++++++++++++
gcc/tree-if-conv.c | 26 ++++++++++++++
4 files changed, 91 insertions(+), 0 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ifc-pr47271.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7f3148a..84fb592 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2011-01-24 Sebastian Pop <sebastian.pop@amd.com>
+ Jakub Jelinek <jakub@redhat.com>
+
+ PR tree-optimization/47271
+ * tree-if-conv.c (bb_postdominates_preds): New.
+ (if_convertible_bb_p): Return false when bb has more than 2
+ predecessors. Call bb_postdominates_preds.
+ (if_convertible_loop_p_1): Compute CDI_POST_DOMINATORS.
+ (predicate_scalar_phi): Call bb_postdominates_preds.
+
2011-01-23 Bernd Schmidt <bernds@codesourcery.com>
Richard Sandiford <rdsandiford@googlemail.com>
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 33d1cda..3238e3a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2011-01-24 Sebastian Pop <sebastian.pop@amd.com>
+ Jakub Jelinek <jakub@redhat.com>
+
+ PR tree-optimization/47271
+ * gcc.dg/tree-ssa/ifc-pr47271.c: New.
+
2011-01-24 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
* lib/scanasm.exp (dg-function-on-line): Handle mips-sgi-irix*.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ifc-pr47271.c b/gcc/testsuite/gcc.dg/tree-ssa/ifc-pr47271.c
new file mode 100644
index 0000000..bf36079
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ifc-pr47271.c
@@ -0,0 +1,49 @@
+/* { dg-options "-O3" } */
+/* { dg-do run } */
+
+extern void abort (void);
+
+void func (void)
+{
+ int i;
+ int nops;
+ char *codestr =
+ "|\000\000Ee\000\000Z\001\000d\000\000Z\002\000d\025\000Z\003\000"
+ "\t\t\t\t\t\t\t\t\t\t\t\td\026\000Z\004\000d\005\000\204\000\000Z"
+ "\005\000e\006\000e\a\000j\005\000e\b\000d\006\000\204\002\000\203"
+ "\001\000Z\t\000d\a\000\204\000\000Z\n\000d\b\000\204\000\000Z\v\000d"
+ "\t\000\204\000\000Z\f\000d\n\000\204\000\000Z\r\000e\016\000e\017\000d"
+ "\v\000\203\001\000d\f\000d\r\000\203\001\001Z\020\000e\016\000e\017"
+ "\000d\016\000\203\001\000d\f\000d\017\000\203\001\001Z\021\000e\016"
+ "\000e\017\000d\020\000\203\001\000d\f\000d\021\000\203\001\001Z\022"
+ "\000e\016\000e\017\000d\022\000\203\001\000d\f\000d\023\000\203\001"
+ "\001Z\023\000d\024\000S";
+ int codelen = 209;
+ int addrmap[500];
+
+ for (i=0, nops=0 ; i<codelen ; i += ((codestr[i] >= 90) ? 3 : 1))
+ {
+ addrmap[i] = i - nops;
+ if (codestr[i] == 9)
+ nops++;
+ }
+
+ if (addrmap[0] != 0
+ || addrmap[3] != 3
+ || addrmap[4] != 4
+ || addrmap[7] != 7
+ || addrmap[10] != 10
+ || addrmap[13] != 13
+ || addrmap[16] != 16
+ || addrmap[19] != 19
+ || addrmap[22] != 22
+ || addrmap[23] != 22
+ || addrmap[24] != 22)
+ abort ();
+}
+
+int main ()
+{
+ func ();
+ return 0;
+}
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 46b20c2..269bad9 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -716,6 +716,20 @@ if_convertible_stmt_p (gimple stmt, VEC (data_reference_p, heap) *refs)
return true;
}
+/* Return true when BB post-dominates all its predecessors. */
+
+static bool
+bb_postdominates_preds (basic_block bb)
+{
+ unsigned i;
+
+ for (i = 0; i < EDGE_COUNT (bb->preds); i++)
+ if (!dominated_by_p (CDI_POST_DOMINATORS, EDGE_PRED (bb, i)->src, bb))
+ return false;
+
+ return true;
+}
+
/* Return true when BB is if-convertible. This routine does not check
basic block's statements and phis.
@@ -774,6 +788,14 @@ if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
return false;
}
+ if (EDGE_COUNT (bb->preds) > 2)
+ return false;
+
+ if (EDGE_COUNT (bb->preds) == 2
+ && bb != loop->header
+ && !bb_postdominates_preds (bb))
+ return false;
+
return true;
}
@@ -992,6 +1014,7 @@ if_convertible_loop_p_1 (struct loop *loop,
return false;
calculate_dominance_info (CDI_DOMINATORS);
+ calculate_dominance_info (CDI_POST_DOMINATORS);
/* Allow statements that can be handled during if-conversion. */
ifc_bbs = get_loop_body_in_if_conv_order (loop);
@@ -1262,6 +1285,9 @@ predicate_scalar_phi (gimple phi, tree cond,
arg_1 = gimple_phi_arg_def (phi, 1);
}
+ gcc_checking_assert (bb == bb->loop_father->header
+ || bb_postdominates_preds (bb));
+
/* Build new RHS using selected condition and arguments. */
rhs = build3 (COND_EXPR, TREE_TYPE (res),
unshare_expr (cond), arg_0, arg_1);
--
1.7.1