67 lines
2.3 KiB
Diff
67 lines
2.3 KiB
Diff
From dc238e97a75835231939e77e8568ccd9bc5187d5 Mon Sep 17 00:00:00 2001
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From: zhanghaijian <z.zhanghaijian@huawei.com>
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Date: Mon, 12 Jul 2021 10:46:16 +0800
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Subject: [PATCH 05/13] [Backport]tree-optimization: Fix load eliding in SM
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Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=0424a5ece5307cc22bbc0fe97edf4707d7a798ed
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This fixes the case of not using the multithreaded model when
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only conditionally storing to the destination. We cannot elide
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the load in this case.
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diff --git a/gcc/testsuite/gcc.dg/torture/pr94949.c b/gcc/testsuite/gcc.dg/torture/pr94949.c
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new file mode 100755
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index 00000000000..6182d77b3cd
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--- /dev/null
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+++ b/gcc/testsuite/gcc.dg/torture/pr94949.c
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@@ -0,0 +1,17 @@
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+/* { dg-do run } */
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+/* { dg-additional-options "-fallow-store-data-races" } */
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+
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+static int x = 1;
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+static volatile int y = -1;
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+int
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+main()
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+{
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+ for (int i = 0; i < 128; ++i)
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+ {
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+ if (i == y)
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+ x = i;
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+ }
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+ if (x != 1)
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+ __builtin_abort ();
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+ return 0;
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+}
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diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
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index b3fd1647fbd..8c33735b1fa 100644
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--- a/gcc/tree-ssa-loop-im.c
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+++ b/gcc/tree-ssa-loop-im.c
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@@ -2128,9 +2128,9 @@ execute_sm (class loop *loop, vec<edge> exits, im_mem_ref *ref)
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fmt_data.orig_loop = loop;
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for_each_index (&ref->mem.ref, force_move_till, &fmt_data);
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+ bool always_stored = ref_always_accessed_p (loop, ref, true);
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if (bb_in_transaction (loop_preheader_edge (loop)->src)
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- || (! flag_store_data_races
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- && ! ref_always_accessed_p (loop, ref, true)))
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+ || (! flag_store_data_races && ! always_stored))
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multi_threaded_model_p = true;
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if (multi_threaded_model_p)
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@@ -2145,8 +2145,10 @@ execute_sm (class loop *loop, vec<edge> exits, im_mem_ref *ref)
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/* Avoid doing a load if there was no load of the ref in the loop.
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Esp. when the ref is not always stored we cannot optimize it
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- away later. */
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- if (ref->loaded && bitmap_bit_p (ref->loaded, loop->num))
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+ away later. But when it is not always stored we must use a conditional
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+ store then. */
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+ if ((!always_stored && !multi_threaded_model_p)
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+ || (ref->loaded && bitmap_bit_p (ref->loaded, loop->num)))
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{
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load = gimple_build_assign (tmp_var, unshare_expr (ref->mem.ref));
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lim_data = init_lim_data (load);
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--
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2.21.0.windows.1
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