================
@@ -312,6 +313,196 @@ bool X86_64::deleteFallThruJmpInsn(InputSection &is,
return true;
}
+void X86_64::relaxCFIJumpTables() const {
+ // Relax CFI jump tables.
+ // - Split jump table into pieces and place target functions inside the jump
+ // table if small enough.
+ // - Move jump table before last called function and delete last branch
+ // instruction.
+ DenseMap<InputSection *, SmallVector<InputSection *, 0>> sectionReplacements;
+ SmallVector<InputSection *, 0> storage;
+ for (OutputSection *osec : ctx.outputSections) {
+ if (!(osec->flags & SHF_EXECINSTR))
+ continue;
+ for (InputSection *sec : getInputSections(*osec, storage)) {
+ if (sec->type != SHT_LLVM_CFI_JUMP_TABLE || sec->entsize == 0 ||
+ sec->size % sec->entsize != 0)
+ continue;
+
+ // We're going to replace the jump table with this list of sections. This
+ // list will be made up of slices of the original section and function
+ // bodies that were moved into the jump table.
+ SmallVector<InputSection *, 0> replacements;
+
+ // r is the only relocation in a jump table entry. Figure out whether it
+ // is a branch pointing to the start of a statically known section that
+ // hasn't already been moved while processing a different jump table
+ // section, and if so return it.
+ auto getMovableSection = [&](Relocation &r) -> InputSection * {
+ if (r.type != R_X86_64_PC32 && r.type != R_X86_64_PLT32)
+ return nullptr;
+ auto *sym = dyn_cast<Defined>(r.sym);
+ if (!sym || sym->isPreemptible || sym->isGnuIFunc() ||
+ sym->value + r.addend != -4ull)
----------------
pcc wrote:
Done
https://github.com/llvm/llvm-project/pull/147424
_______________________________________________
llvm-branch-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
