* [PATCH] Fix PR91293
@ 2019-07-31 13:16 Richard Biener
0 siblings, 0 replies; only message in thread
From: Richard Biener @ 2019-07-31 13:16 UTC (permalink / raw)
To: gcc-patches
The following fixes wrong-code when SLP ends up swapping operands
of a reduction stmt, confusing code-generation later. Fixed by
not doing such swapping.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2019-07-31 Richard Biener <rguenther@suse.de>
PR tree-optimization/91293
* tree-vect-slp.c (vect_build_slp_tree_2): Do not swap operands
of reduction stmts.
* gcc.dg/vect/pr91293-1.c: New testcase.
* gcc.dg/vect/pr91293-2.c: Likewise.
* gcc.dg/vect/pr91293-3.c: Likewise.
Index: gcc/tree-vect-slp.c
===================================================================
--- gcc/tree-vect-slp.c (revision 273930)
+++ gcc/tree-vect-slp.c (working copy)
@@ -1296,6 +1296,9 @@ vect_build_slp_tree_2 (vec_info *vinfo,
&& nops == 2
&& oprnds_info[1]->first_dt == vect_internal_def
&& is_gimple_assign (stmt_info->stmt)
+ /* Swapping operands for reductions breaks assumptions later on. */
+ && STMT_VINFO_DEF_TYPE (stmt_info) != vect_reduction_def
+ && STMT_VINFO_DEF_TYPE (stmt_info) != vect_double_reduction_def
/* Do so only if the number of not successful permutes was nor more
than a cut-ff as re-trying the recursive match on
possibly each level of the tree would expose exponential
Index: gcc/testsuite/gcc.dg/vect/pr91293-1.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr91293-1.c (nonexistent)
+++ gcc/testsuite/gcc.dg/vect/pr91293-1.c (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+/* { dg-additional-options "-msse4.1" { target { sse4_runtime } } } */
+
+long long a;
+unsigned b, c;
+int d = 62;
+void e(long long *f, int p2) { *f = p2; }
+int main()
+{
+ for (int g = 2; g <= d; g++)
+ {
+ b += g + 4;
+ c += 5 - g;
+ }
+ e(&a, b);
+ if (a != 2196)
+ __builtin_abort ();
+ return 0;
+}
Index: gcc/testsuite/gcc.dg/vect/pr91293-2.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr91293-2.c (nonexistent)
+++ gcc/testsuite/gcc.dg/vect/pr91293-2.c (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+/* { dg-additional-options "-msse4.1" { target { sse4_runtime } } } */
+
+long long a;
+unsigned b, c;
+int d = 62;
+void e(long long *f, int p2) { *f = p2; }
+int main()
+{
+ for (int g = 2; g <= d; g++)
+ {
+ c += 5 - g;
+ b += g + 4;
+ }
+ e(&a, b);
+ if (a != 2196)
+ __builtin_abort ();
+ return 0;
+}
Index: gcc/testsuite/gcc.dg/vect/pr91293-3.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr91293-3.c (nonexistent)
+++ gcc/testsuite/gcc.dg/vect/pr91293-3.c (working copy)
@@ -0,0 +1,20 @@
+/* { dg-do run } */
+/* { dg-additional-options "-msse4.1" { target { sse4_runtime } } } */
+
+long long a;
+unsigned b, c;
+int d = 62;
+void e(long long *f, int p2) { *f = p2; }
+int xx = 5, yy = 4;
+int main()
+{
+ for (int g = 2; g <= d; g++)
+ {
+ c += xx - g;
+ b += yy + g;
+ }
+ e(&a, b);
+ if (a != 2196)
+ __builtin_abort ();
+ return 0;
+}
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