ipa-fnsummary: Remove inconsistent bp_pack_value

There is one inconsistent bit-field streaming out and in.
On the side of streaming in:

    bp_pack_value (&bp, info->inlinable, 1);
    bp_pack_value (&bp, false, 1);
    bp_pack_value (&bp, info->fp_expressions, 1);

while on the side of the streaming out:

    info->inlinable = bp_unpack_value (&bp, 1);
    info->fp_expressions = bp_unpack_value (&bp, 1)

The removal of Cilk Plus support r8-4956 missed to remove
the streaming out of the bit, instead just change the value
for streaming out to be always false.

By hacking fp_expression_p to always return true, I can see
it reads the wrong fp_expressions value (false) out in wpa.

GCC12 adopts commit 63c6446f77b9001d26f973114450d790749f282b
which removes the inconsistent streaming out instead.

gcc/ChangeLog:

	* ipa-fnsummary.c (inline_read_section): Unpack a dummy bit
	to keep consistent with the side of streaming out.

diff --git a/gcc/ipa-fnsummary.c b/gcc/ipa-fnsummary.c
index 18bbae145b9bd0a5fc754d54c884bc84a80b8810..bf635c1f78aa72c73b90e9a3af89bc33e6ae8e97 100644 (file)
--- a/gcc/ipa-fnsummary.c
+++ b/gcc/ipa-fnsummary.c
@@ -4403,13 +4403,20 @@ inline_read_section (struct lto_file_decl_data *file_data, const char *data,
       bp = streamer_read_bitpack (&ib);
       if (info)
        {
-          info->inlinable = bp_unpack_value (&bp, 1);
-          info->fp_expressions = bp_unpack_value (&bp, 1);
+         info->inlinable = bp_unpack_value (&bp, 1);
+         /* On the side of streaming out, there is still one bit
+            streamed out between inlinable and fp_expressions bits,
+            which was used for cilk+ before but now always false.
+            To remove the bit packing need to bump LTO minor version,
+            so unpack a dummy bit here to keep consistent instead.  */
+         bp_unpack_value (&bp, 1);
+         info->fp_expressions = bp_unpack_value (&bp, 1);
        }
       else
        {
-          bp_unpack_value (&bp, 1);
-          bp_unpack_value (&bp, 1);
+         bp_unpack_value (&bp, 1);
+         bp_unpack_value (&bp, 1);
+         bp_unpack_value (&bp, 1);
        }
 
       count2 = streamer_read_uhwi (&ib);