commit f2d3e7b6202a91b31290eb1789a85fadbf4d6a81
author Arthur Eubanks <aeubanks@google.com> Sun Mar 24 11:43:15 2024 -0600
committer Copybara-Service <copybara-worker@google.com> Sun Mar 24 10:49:43 2024 -0700
tree 911410e8f3cb7eda761103375ea4e1c35ac61e90
parent adaf04b9e0249e861db974020e940a3ac93e7fbc

[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.

GitOrigin-RevId: 48048051323d5dd74057dc5f32df8c3c323afcd5

ELF/Arch/X86_64.cpp

diff --git a/ELF/Arch/X86_64.cpp b/ELF/Arch/X86_64.cpp
index de45901..a85bf3a 100644
--- a/ELF/Arch/X86_64.cpp
+++ b/ELF/Arch/X86_64.cpp
@@ -328,9 +328,10 @@
         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) {

test/ELF/x86-64-gotpc-relax-too-far.s

diff --git a/test/ELF/x86-64-gotpc-relax-too-far.s b/test/ELF/x86-64-gotpc-relax-too-far.s
index 74aa6d8..ba41faa 100644
--- a/test/ELF/x86-64-gotpc-relax-too-far.s
+++ b/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
@@ -49,6 +52,13 @@
 #--- 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) }
   .got 0x300000 : { *(.got) }
   data 0x400000 : { *(data) }