[PATCH] pragma: Update target option node when optimization changes [PR103515]

["Kewen.Lin" <linkw@linux.ibm.com>]

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Hi,

For a function with optimize pragma, it's possible that the target
options change as optimization options change.  Now we create one
optimization option node when parsing pragma optimize, but don't
create target option node for possible target option changes.  It
makes later processing not detect the target options have actually
changed and doesn't update the target options accordingly.

This patch is to check whether target options have changed when
creating one optimization option node for pragma optimize, and
make one target option node if needed.  The associated test case
shows the difference.  Without this patch, the function foo1 will
perform unrolling which is unexpected.  The reason is that flag
unroll_only_small_loops isn't correctly set for it.  The value
is updated after parsing function foo2, but doesn't get restored
later since both decls don't have DECL_FUNCTION_SPECIFIC_TARGET
set and the hook think we don't need to switch.  With this patch,
there is no unrolling for foo1, which is also consistent with the
behavior by replacing pragma by attribute whether w/ and w/o this
patch.

Bootstrapped and regtested on x86_64-redhat-linux, aarch64-linux-gnu
and powerpc64{,le}-linux-gnu.

Is it ok for trunk?

BR,
Kewen
---
gcc/ChangeLog:

	PR target/103515
	* attribs.c (decl_attributes): Check if target options change and
	create one node if so.

gcc/testsuite/ChangeLog:

	PR target/103515
	* gcc.target/powerpc/pr103515.c: New test.

-----

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---
 gcc/attribs.c                               | 13 ++++++++-
 gcc/testsuite/gcc.target/powerpc/pr103515.c | 30 +++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pr103515.c

diff --git a/gcc/attribs.c b/gcc/attribs.c
index c252f5af07b..761d9760769 100644
--- a/gcc/attribs.c
+++ b/gcc/attribs.c
@@ -607,7 +607,18 @@ decl_attributes (tree *node, tree attributes, int flags,
   if (TREE_CODE (*node) == FUNCTION_DECL
       && optimization_current_node != optimization_default_node
       && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
-    DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
+    {
+      DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
+      tree cur_tree
+	= build_target_option_node (&global_options, &global_options_set);
+      tree old_tree = DECL_FUNCTION_SPECIFIC_TARGET (*node);
+      if (!old_tree)
+	old_tree = target_option_default_node;
+      /* The changes on optimization options can cause the changes in
+	 target options, update it accordingly if it's changed.  */
+      if (old_tree != cur_tree)
+	DECL_FUNCTION_SPECIFIC_TARGET (*node) = cur_tree;
+    }
 
   /* If this is a function and the user used #pragma GCC target, add the
      options to the attribute((target(...))) list.  */
diff --git a/gcc/testsuite/gcc.target/powerpc/pr103515.c b/gcc/testsuite/gcc.target/powerpc/pr103515.c
new file mode 100644
index 00000000000..698b9a93037
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr103515.c
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-loop2_unroll-optimized" } */
+
+/* The pragma specified for foo2 should not affect foo1.
+   Verify compiler won't perform unrolling for foo1.  */
+
+#define N 1024
+extern int a1[N], b1[N], c1[N];
+extern int a2[N], b2[N], c2[N];
+extern int n;
+
+void
+foo1 ()
+{
+  int i;
+  for (i = 0; i < n; i++)
+    c1[i] += a1[i] + b1[i];
+}
+
+#pragma GCC optimize("O3,unroll-loops")
+void
+foo2 ()
+{
+  int i;
+  for (i = 0; i < n; i++)
+    c2[i] += a2[i] + b2[i];
+}
+
+/* { dg-final { scan-rtl-dump-times "optimized: loop unrolled" 1 "loop2_unroll" } } */
+
-- 
2.27.0