[𝘀𝗽𝗿] changes introduced through rebase

Created using spr 1.3.6-beta.1

[skip ci]

Author: pcc

lld/ELF/Arch/X86_64.cpp

@@ -376,6 +376,13 @@ void X86_64::relaxCFIJumpTables() const {
       // because the last entry controls which output section the jump table is
       // placed into, which affects move eligibility for other sections.
       auto *lastSec = [&]() -> InputSection * {
+        // If the jump table section is more aligned than the entry size, skip
+        // this because there's no guarantee that we'll be able to emit a
+        // padding section that places the last entry at a correctly aligned
+        // address.
+        if (sec->addralign > sec->entsize)
+          return nullptr;
+
         Relocation *lastReloc = sec->relocs().end();
         while (lastReloc != sec->relocs().begin() &&
                (lastReloc - 1)->offset >= sec->size - sec->entsize)

lld/test/ELF/x86_64-relax-jump-tables.s

@@ -109,6 +109,23 @@ jmp f12.cfi
 f13:
 jmp f13.cfi
 
+// Jumptable alignment > entsize prevents it from being moved before last
+// function, but moving non-last functions into the jumptable should work.
+// CHECK: <f14>:
+// CHECK-NEXT: <f14.cfi>:
+// CHECK-NEXT: retq $0xe
+.section .text.jt5,"ax",@llvm_cfi_jump_table,8
+.balign 16
+f14:
+jmp f14.cfi
+.balign 8, 0xcc
+
+// CHECK: <f15>:
+// CHECK-NEXT: jmp {{.*}} <f15.cfi>
+f15:
+jmp f15.cfi
+.balign 8, 0xcc
+
 // CHECK: <f1>:
 // CHECK-NEXT: <f1.cfi>:
 // CHECK-NEXT: retq $0x1
@@ -180,5 +197,15 @@ ret $12
 f13.cfi:
 ret $13
 
+.section .text.f14,"ax",@progbits
+f14.cfi:
+ret $14
+
+.section .text.f15,"ax",@progbits
+.balign 64
+f15.cfi:
+ret $15
+.zero 16
+
 // CHECK: <.iplt>:
 // CHECK-NEXT: [[IPLT]]: