[lld][ELF] Allow Arm PC-relative relocations in PIC links (#77304)
The relocations that map to R_ARM_PCA are equivalent to R_PC. They are
PC-relative and safe to use in shared libraries, but have a different
relocation code as they are evaluated differently. Now that LLVM may
generate these relocations in object files, they may occur in
shared libraries or position-independent executables.
GitOrigin-RevId: d21fb06a6e36048e6729c51c351ff8c4055e8381
diff --git a/ELF/Relocations.cpp b/ELF/Relocations.cpp
index 20eb02b..af974d0 100644
--- a/ELF/Relocations.cpp
+++ b/ELF/Relocations.cpp
@@ -210,10 +210,10 @@
// True if this expression is of the form Sym - X, where X is a position in the
// file (PC, or GOT for example).
static bool isRelExpr(RelExpr expr) {
- return oneof<R_PC, R_GOTREL, R_GOTPLTREL, R_MIPS_GOTREL, R_PPC64_CALL,
- R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC, R_RELAX_GOT_PC,
- R_RISCV_PC_INDIRECT, R_PPC64_RELAX_GOT_PC, R_LOONGARCH_PAGE_PC>(
- expr);
+ return oneof<R_PC, R_GOTREL, R_GOTPLTREL, R_ARM_PCA, R_MIPS_GOTREL,
+ R_PPC64_CALL, R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC,
+ R_RELAX_GOT_PC, R_RISCV_PC_INDIRECT, R_PPC64_RELAX_GOT_PC,
+ R_LOONGARCH_PAGE_PC>(expr);
}
static RelExpr toPlt(RelExpr expr) {
diff --git a/test/ELF/arm-adr.s b/test/ELF/arm-adr.s
index 05e8cc2..fee78f9 100644
--- a/test/ELF/arm-adr.s
+++ b/test/ELF/arm-adr.s
@@ -1,6 +1,8 @@
// REQUIRES: arm
// RUN: llvm-mc --triple=armv7a-none-eabi --arm-add-build-attributes -filetype=obj -o %t.o %s
// RUN: ld.lld %t.o -o %t
+/// R_ARM_ALU_PC_G0 referencing a non-preemptible symbol can be used in PIC links.
+// RUN: ld.lld %t.o --shared -o /dev/null
// RUN: llvm-objdump -d --no-show-raw-insn --triple=armv7a-none-eabi %t | FileCheck %s
/// Test the short range cases of R_ARM_ALU_PC_G0. The range of the instruction
