[lld] ELF: Introduce --randomize-section-padding option. (PR #117653)

[via llvm-commits]

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@@ -0,0 +1,125 @@
+# REQUIRES: x86
+# RUN: split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %t/a.s -o %t/a.o
+
+## --randomize-section-padding= inserts segment offset padding and pre-section
+## padding, and does not affect flags. Segment offset padding is only inserted
+## when PT_LOAD changes, as shown by .bss size (.data and .bss share a PT_LOAD).
+
+# RUN: ld.lld --randomize-section-padding=6 %t/a.o -o %t/a.out
+# RUN: llvm-readelf -sS -x .rodata -x .text -x .data %t/a.out | FileCheck --check-prefix=PAD6 %s
+
+# PAD6: .rodata           PROGBITS        0000000000200158 000158 000b8d 00   A  0   0  1
+# PAD6: .text             PROGBITS        0000000000201ce8 000ce8 000270 00  AX  0   0  4
+# PAD6: .data             PROGBITS        0000000000202f58 000f58 000941 00  WA  0   0  1
+# PAD6: .bss              NOBITS          0000000000203899 001899 000003 00  WA  0   0  1
+
+# PAD6: 0000000000203899     0 NOTYPE  LOCAL  DEFAULT     4 a
+# PAD6: 000000000020389a     0 NOTYPE  LOCAL  DEFAULT     4 b
+# PAD6: 000000000020389b     0 NOTYPE  LOCAL  DEFAULT     4 c
+
+# PAD6: Hex dump of section '.rodata':
+# PAD6: 0x00200cd8 00000000 00000000 00000102 03
----------------
pcc wrote:

This one can't use -NEXT (at least not without a lot of boilerplate) because it is preceded by this:
```
Hex dump of section '.rodata':
0x00200158 00000000 00000000 00000000 00000000 ................
0x00200168 00000000 00000000 00000000 00000000 ................
0x00200178 00000000 00000000 00000000 00000000 ................
0x00200188 00000000 00000000 00000000 00000000 ................
0x00200198 00000000 00000000 00000000 00000000 ................
0x002001a8 00000000 00000000 00000000 00000000 ................
...
```

https://github.com/llvm/llvm-project/pull/117653