[llvm-branch-commits] [lld] release/18.x: [lld/ELF][X86] Respect outSecOff when checking if GOTPCREL can be relaxed (#86334) (PR #86688)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/86688

Backport 48048051323d5dd74057dc5f32df8c3c323afcd5

Requested by: @EugeneZelenko

>From 439503ebeb126b44b7fcc8fa73a6912216074745 Mon Sep 17 00:00:00 2001
From: Arthur Eubanks <aeubanks at google.com>
Date: Sun, 24 Mar 2024 11:43:15 -0600
Subject: [PATCH] [lld/ELF][X86] Respect outSecOff when checking if GOTPCREL
 can be relaxed (#86334)

The existing implementation didn't handle when the input text section
was some offset from the output section.

This resulted in an assert in relaxGot() with an lld built with asserts
for some large binaries, or even worse, a silently broken binary with an
lld without asserts.

(cherry picked from commit 48048051323d5dd74057dc5f32df8c3c323afcd5)
---
 lld/ELF/Arch/X86_64.cpp                   |  7 ++++---
 lld/test/ELF/x86-64-gotpc-relax-too-far.s | 12 +++++++++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/lld/ELF/Arch/X86_64.cpp b/lld/ELF/Arch/X86_64.cpp
index de459013595fed..a85bf3aa0c09d1 100644
--- a/lld/ELF/Arch/X86_64.cpp
+++ b/lld/ELF/Arch/X86_64.cpp
@@ -328,9 +328,10 @@ bool X86_64::relaxOnce(int pass) const {
         if (rel.expr != R_RELAX_GOT_PC)
           continue;
 
-        uint64_t v = sec->getRelocTargetVA(
-            sec->file, rel.type, rel.addend,
-            sec->getOutputSection()->addr + rel.offset, *rel.sym, rel.expr);
+        uint64_t v = sec->getRelocTargetVA(sec->file, rel.type, rel.addend,
+                                           sec->getOutputSection()->addr +
+                                               sec->outSecOff + rel.offset,
+                                           *rel.sym, rel.expr);
         if (isInt<32>(v))
           continue;
         if (rel.sym->auxIdx == 0) {
diff --git a/lld/test/ELF/x86-64-gotpc-relax-too-far.s b/lld/test/ELF/x86-64-gotpc-relax-too-far.s
index 74aa6d8f65a0d8..ba41faab67de5c 100644
--- a/lld/test/ELF/x86-64-gotpc-relax-too-far.s
+++ b/lld/test/ELF/x86-64-gotpc-relax-too-far.s
@@ -5,7 +5,10 @@
 # RUN: llvm-objdump --no-print-imm-hex -d %t/bin | FileCheck --check-prefix=DISASM %s
 # RUN: llvm-readelf -S %t/bin | FileCheck --check-prefixes=GOT %s
 # RUN: ld.lld -T %t/lds2 %t/a.o -o %t/bin2
-# RUN: llvm-readelf -S %t/bin2 | FileCheck --check-prefixes=UNNECESSARY-GOT %s
+# RUN: llvm-objdump --no-print-imm-hex -d %t/bin2 | FileCheck --check-prefix=DISASM %s
+# RUN: llvm-readelf -S %t/bin2 | FileCheck --check-prefixes=GOT %s
+# RUN: ld.lld -T %t/lds3 %t/a.o -o %t/bin3
+# RUN: llvm-readelf -S %t/bin3 | FileCheck --check-prefixes=UNNECESSARY-GOT %s
 
 # DISASM:      <_foo>:
 # DISASM-NEXT: movl    2097146(%rip), %eax
@@ -47,6 +50,13 @@ SECTIONS {
   data 0x80200000 : { *(data) }
 }
 #--- lds2
+SECTIONS {
+  .text.foo 0x100000 : { *(.text.foo) }
+  .text 0x1ff000 : { . = . + 0x1000 ; *(.text) }
+  .got 0x300000 : { *(.got) }
+  data 0x80200000 : { *(data) }
+}
+#--- lds3
 SECTIONS {
   .text.foo 0x100000 : { *(.text.foo) }
   .text 0x200000 : { *(.text) }