PR26806, Suspected linker bug with LTO

This patch reverts most of git commit 1e3b96fd6cf, so IR symbols are
again not marked def_regular or ref_regular.  That should be enough to
stop IR symbols from becoming dynamic.  To mark as-needed shared
libraries referenced by IR symbols, use the referencing BFD rather
than the ref flags.

bfd/
	PR 15146
	PR 26314
	PR 26530
	PR 26806
	* elflink.c (elf_link_add_object_symbols): Don't set def/ref flags
	for plugin syms.  Do allow plugin syms to mark as-needed libs.
ld/
	PR 26806
	* testsuite/ld-plugin/lto-19.h,
	* testsuite/ld-plugin/lto-19a.c,
	* testsuite/ld-plugin/lto-19b.c,
	* testsuite/ld-plugin/lto-19c.c: New test.
	* testsuite/ld-plugin/pr26806.c,
	* testsuite/ld-plugin/pr26806.d: New test.
	* testsuite/ld-plugin/lto.exp: Run them.

8 files changed, 74 insertions, 0 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 3f39eb4..f980e62 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,14 @@
+2020-11-02  Alan Modra  <amodra@gmail.com>
+
+	PR 26806
+	* testsuite/ld-plugin/lto-19.h,
+	* testsuite/ld-plugin/lto-19a.c,
+	* testsuite/ld-plugin/lto-19b.c,
+	* testsuite/ld-plugin/lto-19c.c: New test.
+	* testsuite/ld-plugin/pr26806.c,
+	* testsuite/ld-plugin/pr26806.d: New test.
+	* testsuite/ld-plugin/lto.exp: Run them.
+
 2020-10-30  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR gas/26703
diff --git a/ld/testsuite/ld-plugin/lto-19.h b/ld/testsuite/ld-plugin/lto-19.h
new file mode 100644
index 0000000..0ca48d1
--- /dev/null
+++ b/ld/testsuite/ld-plugin/lto-19.h
@@ -0,0 +1,6 @@
+struct re_dfa_t {
+  const int *sb_char;
+};
+struct re_dfa_t *xregcomp (void);
+struct re_dfa_t *rpl_regcomp (void);
+void rpl_regfree (struct re_dfa_t *);
diff --git a/ld/testsuite/ld-plugin/lto-19a.c b/ld/testsuite/ld-plugin/lto-19a.c
new file mode 100644
index 0000000..6213f79
--- /dev/null
+++ b/ld/testsuite/ld-plugin/lto-19a.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "lto-19.h"
+
+static const int utf8_sb_map[4] = { 0x12, 0x34, 0x56, 0x78 };
+
+struct re_dfa_t *
+rpl_regcomp ()
+{
+  struct re_dfa_t *dfa = malloc (sizeof (struct re_dfa_t));
+  dfa->sb_char = utf8_sb_map;
+  return dfa;
+}
+
+void
+rpl_regfree (struct re_dfa_t *dfa)
+{
+  puts (dfa->sb_char == utf8_sb_map ? "PASS" : "FAIL");
+}
diff --git a/ld/testsuite/ld-plugin/lto-19b.c b/ld/testsuite/ld-plugin/lto-19b.c
new file mode 100644
index 0000000..b784f84
--- /dev/null
+++ b/ld/testsuite/ld-plugin/lto-19b.c
@@ -0,0 +1,7 @@
+#include "lto-19.h"
+
+struct re_dfa_t *
+xregcomp (void)
+{
+  return rpl_regcomp ();
+}
diff --git a/ld/testsuite/ld-plugin/lto-19c.c b/ld/testsuite/ld-plugin/lto-19c.c
new file mode 100644
index 0000000..0d231ba
--- /dev/null
+++ b/ld/testsuite/ld-plugin/lto-19c.c
@@ -0,0 +1,9 @@
+#include "lto-19.h"
+
+int
+main ()
+{
+  struct re_dfa_t *dfa = xregcomp ();
+  rpl_regfree (dfa);
+  return 0;
+}
diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 9f9f2d1..23c948c 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -403,6 +403,18 @@ set lto_link_elf_tests [list \
   [list {lto-18d.o} \
    {} {-flto -O2} \
    {lto-18d.c} {} {}] \
+  [list {liblto-19.a} \
+   "$plug_opt" {-flto -O2 -fPIC} \
+   {lto-19a.c} {} {liblto-19.a}] \
+  [list {compile lto-19b.c} \
+   "$plug_opt" {-flto -O2 -fPIC} \
+   {lto-19b.c} {} {} {c}] \
+  [list {liblto-19.so} \
+   {-shared tmpdir/lto-19b.o tmpdir/liblto-19.a} {-O2 -fPIC} \
+   {dummy.c} {} {liblto-19.so}] \
+  [list {pr26806.so} \
+   {-shared} {-fpic -O2 -flto} \
+   {pr26806.c} {{nm {-D} pr26806.d}} {pr26806.so}] \
 ]
 
 # PR 14918 checks that libgcc is not spuriously included in a shared link of
@@ -584,6 +596,10 @@ set lto_run_elf_shared_tests [list \
    {-static -flto -fuse-linker-plugin} {} \
    {lto-18a.c} {lto-18-4.exe} {lto-18.out} {-flto -O2} {c} {} \
    { -Ltmpdir -llto-18b -llto-18c tmpdir/lto-18d.o}] \
+  [list {lto-19} \
+   {-Wl,--as-needed,-R,tmpdir} {} \
+   {lto-19c.c} {lto-19.exe} {pass.out} {-flto -O2} {c} {} \
+   {tmpdir/liblto-19.so tmpdir/liblto-19.a}] \
 ]
 
 # LTO run-time tests for ELF
diff --git a/ld/testsuite/ld-plugin/pr26806.c b/ld/testsuite/ld-plugin/pr26806.c
new file mode 100644
index 0000000..8bb2931
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr26806.c
@@ -0,0 +1,2 @@
+#include <unistd.h>
+int foo (int x) { if (__builtin_constant_p (x)) return getpid (); return 0; }
diff --git a/ld/testsuite/ld-plugin/pr26806.d b/ld/testsuite/ld-plugin/pr26806.d
new file mode 100644
index 0000000..16fa828
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr26806.d
@@ -0,0 +1,4 @@
+#failif
+#...
+.* _*getpid[@ ].*
+#...