https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86517
--- Comment #7 from Jan Hubicka <hubicka at ucw dot cz> ---
Hi,
I am attaching patch I am testing and also table generated by a script that
walks through individual combinations of options. The combination rules are as
follows.
I tried to take into account that targets may default to some form of PIC or
PIE. That is why, for example combining -fpic and empty options results in
empty options and no no-pic.
Note that in addition to lto-wrapper option merging we now have logic that
disables PIC/PIE when final binary is built based on lto-plugion output (it
knows if it builds binary, relocatable binary, library or incrementally links).
Still we rely on the merging to choose particular form of PIC/PIE and we need
it right in incremental link where linker does not help us.
-fpic + -fpic => -fpic
-fpic + -fPIC => -fpic
-fpic + -fpie => -fpie
-fpic + -fPIE => -fpie
-fpic + -fno-pic => -fno-pic
-fpic + -fno-pie =>
-fpic + =>
-fPIC + -fpic => -fpic
-fPIC + -fPIC => -fPIC
-fPIC + -fpie => -fpie
-fPIC + -fPIE => -fPIE
-fPIC + -fno-pic => -fno-pic
-fPIC + -fno-pie =>
-fPIC + =>
-fpie + -fpic => -fpie
-fpie + -fPIC => -fpie
-fpie + -fpie => -fpie
-fpie + -fPIE => -fpie
-fpie + -fno-pic =>
-fpie + -fno-pie =>
-fpie + =>
-fPIE + -fpic => -fpie
-fPIE + -fPIC => -fPIE
-fPIE + -fpie => -fpie
-fPIE + -fPIE => -fPIE
-fPIE + -fno-pic =>
-fPIE + -fno-pie =>
-fPIE + =>
-fno-pic + -fpic => -fno-pic
-fno-pic + -fPIC => -fno-pic
-fno-pic + -fpie => -fno-pic
-fno-pic + -fPIE => -fno-pic
-fno-pic + -fno-pic => -fno-pic
-fno-pic + -fno-pie => -fno-pic
-fno-pic + => -fno-pic
-fno-pie + -fpic => -fno-pie
-fno-pie + -fPIC => -fno-pie
-fno-pie + -fpie => -fno-pie
-fno-pie + -fPIE => -fno-pie
-fno-pie + -fno-pic => -fno-pie
-fno-pie + -fno-pie => -fno-pie
-fno-pie + => -fno-pie
-fpic + =>
-fPIC + =>
-fpie + =>
-fPIE + =>
-fno-pic + =>
-fno-pie + =>
+ =>
Index: lto-wrapper.c
===================================================================
--- lto-wrapper.c (revision 262682)
+++ lto-wrapper.c (working copy)
@@ -408,6 +408,11 @@ merge_and_complain (struct cl_decoded_op
It is a common mistake to mix few -fPIC compiled objects into otherwise
non-PIC code. We do not want to build everything with PIC then.
+ Similarly we merge PIE options, however in addition we keep
+ -fPIC + -fPIE = -fPIE
+ -fpic + -fPIE = -fpie
+ -fPIC/-fpic + -fpie = -fpie
+
It would be good to warn on mismatches, but it is bit hard to do as
we do not know what nothing translates to. */
@@ -415,11 +420,34 @@ merge_and_complain (struct cl_decoded_op
if ((*decoded_options)[j].opt_index == OPT_fPIC
|| (*decoded_options)[j].opt_index == OPT_fpic)
{
- if (!pic_option
- || (pic_option->value > 0) != ((*decoded_options)[j].value > 0))
- remove_option (decoded_options, j, decoded_options_count);
- else if (pic_option->opt_index == OPT_fPIC
- && (*decoded_options)[j].opt_index == OPT_fpic)
+ /* -fno-pic in one unit implies -fno-pic everywhere. */
+ if ((*decoded_options)[j].value == 0)
+ j++;
+ /* If we have no pic option or merge in -fno-pic, we still may turn
+ existing pic/PIC mode into pie/PIE if -fpie/-fPIE is present. */
+ else if ((pic_option && pic_option->value == 0)
+ || !pic_option)
+ {
+ if (pie_option && pie_option->value > 0)
+ {
+ bool big = (*decoded_options)[j].opt_index == OPT_fPIC
+ && pie_option->opt_index == OPT_fPIE;
+ (*decoded_options)[j].opt_index = big ? OPT_fPIE : OPT_fpie;
+ (*decoded_options)[j].canonical_option[0] = big ? "-fPIE" :
"-fpie";
+ j++;
+ }
+ else if (pic_option)
+ {
+ (*decoded_options)[j] = *pic_option;
+ j++;
+ }
+ /* We do not know if target defaults to pic or not, so just remove
+ option if it is missing in one unit but enabled in other. */
+ else
+ remove_option (decoded_options, j, decoded_options_count);
+ }
+ else if (pic_option->opt_index == OPT_fpic
+ && (*decoded_options)[j].opt_index == OPT_fPIC)
{
(*decoded_options)[j] = *pic_option;
j++;
@@ -430,11 +458,37 @@ merge_and_complain (struct cl_decoded_op
else if ((*decoded_options)[j].opt_index == OPT_fPIE
|| (*decoded_options)[j].opt_index == OPT_fpie)
{
- if (!pie_option
- || pie_option->value != (*decoded_options)[j].value)
- remove_option (decoded_options, j, decoded_options_count);
- else if (pie_option->opt_index == OPT_fPIE
- && (*decoded_options)[j].opt_index == OPT_fpie)
+ /* -fno-pie in one unit implies -fno-pie everywhere. */
+ if ((*decoded_options)[j].value == 0)
+ j++;
+ /* If we have no pie option or merge in -fno-pie, we still preserve
+ PIE/pie if pic/PIC is present. */
+ else if ((pie_option && pie_option->value == 0)
+ || !pie_option)
+ {
+ /* If -fPIC/-fpic is given, merge it with -fPIE/-fpie. */
+ if (pic_option && pic_option->value > 0)
+ {
+ if (pic_option->opt_index == OPT_fpic
+ && (*decoded_options)[j].opt_index == OPT_fPIE)
+ {
+ (*decoded_options)[j].opt_index = OPT_fpie;
+ (*decoded_options)[j].canonical_option[0] = "-fpie";
+ }
+ j++;
+ }
+ /* Target may default to pic. */
+ else if (pie_option && pic_option)
+ {
+ (*decoded_options)[j] = *pie_option;
+ j++;
+ }
+ /* Target may default to pie. */
+ else
+ remove_option (decoded_options, j, decoded_options_count);
+ }
+ else if (pie_option->opt_index == OPT_fpie
+ && (*decoded_options)[j].opt_index == OPT_fPIE)
{
(*decoded_options)[j] = *pie_option;
j++;
