[ELF][MIPS] Fix calculation of GP relative relocations in case of relocatable output

Some MIPS relocations depend on "gp" value. By default, this value has
0x7ff0 offset from a .got section. But relocatable files produced by a
compiler or a linker might redefine this default value and we have to
use it for a calculation of the relocation result. When we generate EXE
or DSO it's trivial. Generating a relocatable output is more difficult
case because the linker does calculate relocations in this case and
cannot store individual "gp" values used by each input object file.
As a workaround we add the "gp" value to the relocation addend.

This fixes https://llvm.org/pr31149

Differential revision: https://reviews.llvm.org/D45972

llvm-svn: 331772

4 files changed, 66 insertions, 9 deletions

diff --git a/lld/test/ELF/Inputs/mips-micro-gp0-non-zero.o b/lld/test/ELF/Inputs/mips-micro-gp0-non-zero.o
new file mode 100644
index 00000000000..abd67bcd262
--- /dev/null
+++ b/lld/test/ELF/Inputs/mips-micro-gp0-non-zero.o
diff --git a/lld/test/ELF/Inputs/mips-n64-gp0-non-zero.o b/lld/test/ELF/Inputs/mips-n64-gp0-non-zero.o
new file mode 100644
index 00000000000..43b930b9d9f
--- /dev/null
+++ b/lld/test/ELF/Inputs/mips-n64-gp0-non-zero.o
diff --git a/lld/test/ELF/mips-gprel32-relocs-gp0.s b/lld/test/ELF/mips-gprel32-relocs-gp0.s
index 507224e05d1..f27caa33010 100644
--- a/lld/test/ELF/mips-gprel32-relocs-gp0.s
+++ b/lld/test/ELF/mips-gprel32-relocs-gp0.s
@@ -1,8 +1,4 @@
 # Check that relocatable object produced by LLD has zero gp0 value.
-# Also check an error message if input object file has non-zero gp0 value
-# and the linker generates a relocatable object.
-# mips-gp0-non-zero.o is a relocatable object produced from the asm code
-# below and linked by GNU bfd linker.
 
 # RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
 # RUN: ld.lld -r -o %t-rel.o %t.o
@@ -12,9 +8,6 @@
 # RUN: llvm-readobj -mips-reginfo %t.so | FileCheck --check-prefix=DSO %s
 # RUN: llvm-objdump -s -t %t.so | FileCheck --check-prefix=DUMP %s
 
-# RUN: not ld.lld -r -o %t-rel.o %S/Inputs/mips-gp0-non-zero.o 2>&1 \
-# RUN:   | FileCheck --check-prefix=ERR %s
-
 # REQUIRES: mips
 
 # REL: GP: 0x0
@@ -31,8 +24,6 @@
 # DUMP: 00010004         .text          00000000 foo
 # DUMP: 00027ff0         .got           00000000 .hidden _gp
 
-# ERR: error: {{.*}}mips-gp0-non-zero.o: unsupported non-zero ri_gp_value
-
   .text
   .global  __start
 __start:
diff --git a/lld/test/ELF/mips-non-zero-gp0.s b/lld/test/ELF/mips-non-zero-gp0.s
new file mode 100644
index 00000000000..3582e3ce676
--- /dev/null
+++ b/lld/test/ELF/mips-non-zero-gp0.s
@@ -0,0 +1,66 @@
+# REQUIRES: mips
+
+# Check addend adjustment in case of generating a relocatable object
+# if some input files have non-zero GP0 value.
+
+# We have to use GNU as and ld.bfd 2.28 to generate relocatable object
+# files with non-zero GP0 value using the following command lines:
+#
+# as -mips32 -o test.o \
+#   && ld.bfd -m elf32btsmip -r test.o -o mips-gp0-non-zero.o
+# as -mips64 -mmicromips -o test.o \
+#   && ld.bfd -m elf64btsmip -r test.o -o mips-micro-gp0-non-zero.o
+# as -mips64 -o test.o \
+#   && ld.bfd -m elf64btsmip -r test.o -o mips-n64-gp0-non-zero.o
+
+# Source code for mips-gp0-non-zero.o:
+#   .text
+#   .global  __start
+# __start:
+#   lw      $t0,%call16(__start)($gp)
+# foo:
+#   nop
+# bar:
+#   nop
+#
+#   .section .rodata, "a"
+# v:
+#   .gpword foo
+#   .gpword bar
+
+# Source code for mips-n64-gp0-non-zero.o and mips-micro-gp0-non-zero.o:
+#   .text
+#   .global  __start
+# __start:
+# foo:
+#   lui     $gp,%hi(%neg(%gp_rel(foo)))
+
+# RUN: ld.lld -r -o %t-32.r %S/Inputs/mips-gp0-non-zero.o
+# RUN: llvm-readobj -mips-reginfo %t-32.r | FileCheck --check-prefix=GPVAL %s
+# RUN: llvm-objdump -s %t-32.r | FileCheck --check-prefix=ADDEND32 %s
+
+# RUN: ld.lld -r -o %t-64.r %S/Inputs/mips-n64-gp0-non-zero.o
+# RUN: llvm-readobj -mips-options %t-64.r | FileCheck --check-prefix=GPVAL %s
+# RUN: llvm-readobj -r %S/Inputs/mips-n64-gp0-non-zero.o %t-64.r \
+# RUN:   | FileCheck --check-prefix=ADDEND64 %s
+
+# RUN: ld.lld -r -o %t-micro.r %S/Inputs/mips-micro-gp0-non-zero.o
+# RUN: llvm-readobj -mips-options %t-micro.r | FileCheck --check-prefix=GPVAL %s
+# RUN: llvm-readobj -r %S/Inputs/mips-micro-gp0-non-zero.o %t-micro.r \
+# RUN:   | FileCheck --check-prefix=ADDENDMM %s
+
+# GPVAL: GP: 0x0
+
+# ADDEND32:      Contents of section .rodata:
+# ADDEND32-NEXT:  0000 00007ff4 00007ff8
+#                      ^ 4+GP0  ^ 8+GP0
+
+# ADDEND64: File: {{.*}}/Inputs/mips-n64-gp0-non-zero.o
+# ADDEND64: .text 0xFFFFFFFFFFFF8011
+# ADDEND64: File: {{.*}}/mips-non-zero-gp0.s.tmp-64.r
+# ADDEND64: .text 0x0
+
+# ADDENDMM: File: {{.*}}/Inputs/mips-micro-gp0-non-zero.o
+# ADDENDMM: .text 0xFFFFFFFFFFFF8012
+# ADDENDMM: File: {{.*}}/mips-non-zero-gp0.s.tmp-micro.r
+# ADDENDMM: .text 0x1