================
@@ -513,29 +547,125 @@ void RISCV::relocate(uint8_t *loc, const Relocation
&rel, uint64_t val) const {
break;
case R_RISCV_RELAX:
- return; // Ignored (for now)
-
+ return;
+ case R_RISCV_TLSDESC:
+ // The addend is stored in the second word.
+ if (config->is64)
+ write64le(loc + 8, val);
+ else
+ write32le(loc + 4, val);
+ break;
default:
llvm_unreachable("unknown relocation");
}
}
+static void tlsdescToIe(uint8_t *loc, const Relocation &rel, uint64_t val) {
+ switch (rel.type) {
+ case R_RISCV_TLSDESC_HI20:
+ case R_RISCV_TLSDESC_LOAD_LO12:
+ write32le(loc, 0x00000013); // nop
+ break;
+ case R_RISCV_TLSDESC_ADD_LO12:
+ write32le(loc, utype(AUIPC, X_A0, hi20(val))); // auipc a0,<hi20>
+ break;
+ case R_RISCV_TLSDESC_CALL:
+ if (config->is64)
+ write32le(loc, itype(LD, X_A0, X_A0, lo12(val))); // ld a0,<lo12>(a0)
+ else
+ write32le(loc, itype(LW, X_A0, X_A0, lo12(val))); // lw a0,<lo12>(a0)
+ break;
+ default:
+ llvm_unreachable("unsupported relocation for TLSDESC to IE");
+ }
+}
+
+static void tlsdescToLe(uint8_t *loc, const Relocation &rel, uint64_t val) {
+ switch (rel.type) {
+ case R_RISCV_TLSDESC_HI20:
+ case R_RISCV_TLSDESC_LOAD_LO12:
+ write32le(loc, 0x00000013); // nop
+ return;
+ case R_RISCV_TLSDESC_ADD_LO12:
+ if (isInt<12>(val))
+ write32le(loc, 0x00000013); // nop
+ else
+ write32le(loc, utype(LUI, X_A0, hi20(val))); // lui a0,<hi20>
+ return;
+ case R_RISCV_TLSDESC_CALL:
+ if (isInt<12>(val))
+ write32le(loc, itype(ADDI, X_A0, 0, val)); // addi a0,zero,<lo12>
+ else
+ write32le(loc, itype(ADDI, X_A0, X_A0, lo12(val))); // addi a0,a0,<lo12>
+ return;
+ default:
+ llvm_unreachable("unsupported relocation for TLSDESC to LE");
+ }
+}
+
void RISCV::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
uint64_t secAddr = sec.getOutputSection()->addr;
if (auto *s = dyn_cast<InputSection>(&sec))
secAddr += s->outSecOff;
else if (auto *ehIn = dyn_cast<EhInputSection>(&sec))
secAddr += ehIn->getParent()->outSecOff;
- for (size_t i = 0, size = sec.relocs().size(); i != size; ++i) {
- const Relocation &rel = sec.relocs()[i];
+ uint64_t tlsdescVal = 0;
+ bool isToLe = false;
+ const ArrayRef<Relocation> relocs = sec.relocs();
+ for (size_t i = 0, size = relocs.size(); i != size; ++i) {
+ const Relocation &rel = relocs[i];
uint8_t *loc = buf + rel.offset;
- const uint64_t val =
+ uint64_t val =
sec.getRelocTargetVA(sec.file, rel.type, rel.addend,
secAddr + rel.offset, *rel.sym, rel.expr);
switch (rel.expr) {
case R_RELAX_HINT:
+ continue;
+ case R_TLSDESC_PC:
+ // For R_RISCV_TLSDESC_HI20, store &got(sym)-PC to be used by the
+ // following two instructions L[DW] and ADDI.
+ if (rel.type == R_RISCV_TLSDESC_HI20)
+ tlsdescVal = val;
+ else
+ val = tlsdescVal;
break;
+ case R_RELAX_TLS_GD_TO_IE:
+ // Only R_RISCV_TLSDESC_HI20 reaches here. tlsdescVal will be finalized
+ // after we see R_RISCV_TLSDESC_ADD_LO12 in the R_RELAX_TLS_GD_TO_LE
case.
+ // The net effect is that tlsdescVal will be smaller than `val` to take
+ // into account of NOP instructions (in the absence of R_RISCV_RELAX)
+ // before AUIPC.
+ tlsdescVal = val + rel.offset;
+ isToLe = false;
+ if (!(i + 1 != relocs.size() && relocs[i + 1].type == R_RISCV_RELAX))
+ tlsdescToIe(loc, rel, val);
+ continue;
+ case R_RELAX_TLS_GD_TO_LE:
+ // See the comment in handleTlsRelocation. For TLSDESC=>IE,
+ // R_RISCV_TLSDESC_{LOAD_LO12,ADD_LO12,CALL} also reach here. If isToIe
is
+ // true, this is actually TLSDESC=>IE optimization.
+ if (rel.type == R_RISCV_TLSDESC_HI20) {
+ tlsdescVal = val;
+ isToLe = true;
+ } else {
+ if (!isToLe && rel.type == R_RISCV_TLSDESC_ADD_LO12)
+ tlsdescVal -= rel.offset;
+ val = tlsdescVal;
+ }
+ // When NOP conversion is eligible and R_RISCV_RELAX is present, don't
+ // write a NOP in case an unrelated instruction follows the current
+ // instruction.
+ if ((rel.type == R_RISCV_TLSDESC_HI20 ||
+ rel.type == R_RISCV_TLSDESC_LOAD_LO12 ||
+ (rel.type == R_RISCV_TLSDESC_ADD_LO12 && isToLe && !hi20(val))) &&
+ i + 1 != relocs.size() && relocs[i + 1].type == R_RISCV_RELAX)
----------------
ilovepi wrote:
This is a pretty complicated condition ... I know its a one off, but do you
think it makes sense to use a helper, just for the readability aspect? Maybe
`canReplaceTlLSDESCWithNop()` or `isTLSDESCRelocElegibleForNop()`?
It may make sense to at least use a helper for
`!(i + 1 != relocs.size() && relocs[i + 1].type == R_RISCV_RELAX` since its
used another time.
I'm fine either way, since this is a style choice(and is really a nit), but I
think it would be easier to understand of some of the complexity was abstracted
away.
https://github.com/llvm/llvm-project/pull/79239
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