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* [gcc r12-1836] tree-optimization/101173 - fix interchange dependence checking
@ 2021-06-28 6:33 Richard Biener
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From: Richard Biener @ 2021-06-28 6:33 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:0ad9d88a3d7170b3d864693c9eb512f89a5096ff
commit r12-1836-g0ad9d88a3d7170b3d864693c9eb512f89a5096ff
Author: Richard Biener <rguenther@suse.de>
Date: Wed Jun 23 09:59:28 2021 +0200
tree-optimization/101173 - fix interchange dependence checking
This adjusts the loop interchange dependence checking to disallow
an outer loop dependence distance of zero.
2021-06-23 Richard Biener <rguenther@suse.de>
PR tree-optimization/101173
* gimple-loop-interchange.cc
(tree_loop_interchange::valid_data_dependences): Disallow outer
loop dependence distance of zero.
* gcc.dg/torture/pr101173.c: New testcase.
Diff:
---
gcc/gimple-loop-interchange.cc | 4 ++--
gcc/testsuite/gcc.dg/torture/pr101173.c | 18 ++++++++++++++++++
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/gcc/gimple-loop-interchange.cc b/gcc/gimple-loop-interchange.cc
index 80f749b6071..43045c5455e 100644
--- a/gcc/gimple-loop-interchange.cc
+++ b/gcc/gimple-loop-interchange.cc
@@ -1043,8 +1043,8 @@ tree_loop_interchange::valid_data_dependences (unsigned i_idx, unsigned o_idx,
continue;
/* Be conservative, skip case if either direction at i_idx/o_idx
- levels is not '=' or '<'. */
- if (dist_vect[i_idx] < 0 || dist_vect[o_idx] < 0)
+ levels is not '=' (for the inner loop) or '<'. */
+ if (dist_vect[i_idx] < 0 || dist_vect[o_idx] <= 0)
return false;
}
}
diff --git a/gcc/testsuite/gcc.dg/torture/pr101173.c b/gcc/testsuite/gcc.dg/torture/pr101173.c
new file mode 100644
index 00000000000..0c9090d6686
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr101173.c
@@ -0,0 +1,18 @@
+/* { dg-do run } */
+/* { dg-additional-options "-floop-interchange" } */
+
+int a[6][9];
+int main()
+{
+ a[1][3] = 8;
+ for (int b = 1; b <= 5; b++)
+ for (int d = 0; d <= 5; d++)
+#pragma GCC unroll 0
+ for (int c = 0; c <= 5; c++)
+ a[b][c] = a[b][c + 2] & 216;
+ for (int e = 0; e < 6; e++)
+ for (int f = 0; f < 9; f++)
+ if (a[e][f] != 0)
+ __builtin_abort ();
+ return 0;
+}
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