This was noticed while trying to test -msave-restore support. The
save/restore routines use the alternate return register t0/x5 which is
clobbered by the PLT header, so we can't use them in shared libraries.
This patch disables -msave-restore when -fpic (and -mplt), and emits a
warning if the user explicitly turned on -msave-restore.
Tested with a riscv64-linux cross compiler build and make check with the
option -msave-restore hardwired on. There are thousands of failures without
the patch. With the patch I get a reasonable number of failures. Also
tested by hand to verify I get the warning when the user specifies the option.
Committed.
Jim
gcc/
* config/riscv/riscv.c (riscv_option_override): If -msave-restore
and -fpic and -mplt then disable -msave-restore and warn.
---
gcc/config/riscv/riscv.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/gcc/config/riscv/riscv.c b/gcc/config/riscv/riscv.c
index 9b16a1eb9c2..1e7528f1cb9 100644
--- a/gcc/config/riscv/riscv.c
+++ b/gcc/config/riscv/riscv.c
@@ -4636,6 +4636,16 @@ riscv_option_override (void)
error ("%<-mriscv-attribute%> RISC-V ELF attribute requires GNU as 2.32"
" [%<-mriscv-attribute%>]");
#endif
+
+ /* The save-restore routines use t0 which is clobbered by the plt header,
+ so we can't use them when building shared libraries. */
+ if (TARGET_SAVE_RESTORE && flag_pic && TARGET_PLT)
+ {
+ target_flags &= ~MASK_SAVE_RESTORE;
+ if (target_flags_explicit & MASK_SAVE_RESTORE)
+ warning (0, "%<-msave-restore%> disabled; not supported with PLT "
+ "based shared libraries");
+ }
}
/* Implement TARGET_CONDITIONAL_REGISTER_USAGE. */
--
2.17.1
