[llvm][lld] Support R_AARCH64_GOTPCREL32 #72584

PiJoules · 2023-11-16T23:19:31Z

This is the follopw implementation to
ARM-software/abi-aa#223 that supports this relocation in llvm and lld.

llvmbot · 2023-11-16T23:19:58Z

@llvm/pr-subscribers-lld-elf
@llvm/pr-subscribers-llvm-binary-utilities

@llvm/pr-subscribers-mc

Author: None (PiJoules)

Changes

This is the follopw implementation to
ARM-software/abi-aa#223 that supports this relocation in llvm and lld.

Full diff: https://github.com/llvm/llvm-project/pull/72584.diff

5 Files Affected:

(modified) lld/ELF/Arch/AArch64.cpp (+3)
(added) lld/test/ELF/aarch64-reloc-gotpcrel32.s (+36)
(modified) llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def (+2)
(modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp (+5-2)
(added) llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s (+14)

diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 048f0ec30ebd283..32cff73955028e4 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -165,6 +165,8 @@ RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
   case R_AARCH64_ADR_GOT_PAGE:
   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
     return R_AARCH64_GOT_PAGE_PC;
+  case R_AARCH64_GOTPCREL32:
+    return R_GOT_PC;
   case R_AARCH64_NONE:
     return R_NONE;
   default:
@@ -374,6 +376,7 @@ void AArch64::relocate(uint8_t *loc, const Relocation &rel,
     write32(loc, val);
     break;
   case R_AARCH64_PLT32:
+  case R_AARCH64_GOTPCREL32:
     checkInt(loc, val, 32, rel);
     write32(loc, val);
     break;
diff --git a/lld/test/ELF/aarch64-reloc-gotpcrel32.s b/lld/test/ELF/aarch64-reloc-gotpcrel32.s
new file mode 100644
index 000000000000000..7ea55bfc5b00aad
--- /dev/null
+++ b/lld/test/ELF/aarch64-reloc-gotpcrel32.s
@@ -0,0 +1,36 @@
+// REQUIRES: aarch64
+// RUN: llvm-mc -filetype=obj -triple=aarch64 %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=aarch64 %S/Inputs/abs255.s -o %t255.o
+// RUN: ld.lld %t.o -o %t.so -shared
+// RUN: llvm-readobj -S %t.so | FileCheck --check-prefix=SEC %s
+// RUN: llvm-objdump --no-print-imm-hex -s -d %t.so | FileCheck %s
+
+
+// SEC:         Name: .got (58)
+// SEC-NEXT:    Type: SHT_PROGBITS (0x1)
+// SEC-NEXT:    Flags [ (0x3)
+// SEC-NEXT:      SHF_ALLOC (0x2)
+// SEC-NEXT:      SHF_WRITE (0x1)
+// SEC-NEXT:    ]
+// SEC-NEXT:    Address: 0x20350
+// SEC-NEXT:    Offset: 0x350
+// SEC-NEXT:    Size: 8
+// SEC-NEXT:    Link: 0
+// SEC-NEXT:    Info: 0
+// SEC-NEXT:    AddressAlignment: 8
+// SEC-NEXT:    EntrySize: 0
+
+  .section .data
+  .globl bar
+bar:
+
+  .globl _start
+_start:
+// bar@GOTPCREL   = 0x20350 (got entry for `bar`) - 0x30358 (.) = 0xfffefff8
+// bar@GOTPCREL+4 = 0x20350 (got entry for `bar`) - 0x3035c (.) + 4 = 0xfffefff8
+// bar@GOTPCREL-4 = 0x20350 (got entry for `bar`) - 0x30360 (.) + 4 = 0xfffeffec
+// CHECK: Contents of section .data:
+// CHECK:  30358 f8fffeff f8fffeff ecfffeff
+  .word bar@GOTPCREL
+  .word bar@GOTPCREL+4
+  .word bar@GOTPCREL-4
diff --git a/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def b/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
index b507109b19e1b90..fcaea2aceed5209 100644
--- a/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
+++ b/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
@@ -59,6 +59,7 @@ ELF_RELOC(R_AARCH64_ADR_GOT_PAGE,                    0x137)
 ELF_RELOC(R_AARCH64_LD64_GOT_LO12_NC,                0x138)
 ELF_RELOC(R_AARCH64_LD64_GOTPAGE_LO15,               0x139)
 ELF_RELOC(R_AARCH64_PLT32,                           0x13a)
+ELF_RELOC(R_AARCH64_GOTPCREL32,                      0x13b)
 ELF_RELOC(R_AARCH64_TLSGD_ADR_PREL21,                0x200)
 ELF_RELOC(R_AARCH64_TLSGD_ADR_PAGE21,                0x201)
 ELF_RELOC(R_AARCH64_TLSGD_ADD_LO12_NC,               0x202)
@@ -166,6 +167,7 @@ ELF_RELOC(R_AARCH64_P32_ADR_GOT_PAGE,                0x01a)
 ELF_RELOC(R_AARCH64_P32_LD32_GOT_LO12_NC,            0x01b)
 ELF_RELOC(R_AARCH64_P32_LD32_GOTPAGE_LO14,           0x01c)
 ELF_RELOC(R_AARCH64_P32_PLT32,                       0x01d)
+ELF_RELOC(R_AARCH64_P32_GOTPCREL32,                  0x01e)
 ELF_RELOC(R_AARCH64_P32_TLSGD_ADR_PREL21,            0x050)
 ELF_RELOC(R_AARCH64_P32_TLSGD_ADR_PAGE21,            0x051)
 ELF_RELOC(R_AARCH64_P32_TLSGD_ADD_LO12_NC,           0x052)
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
index 9de40661298ccad..996fd1614d19f57 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
@@ -120,7 +120,8 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
 
   assert((!Target.getSymA() ||
           Target.getSymA()->getKind() == MCSymbolRefExpr::VK_None ||
-          Target.getSymA()->getKind() == MCSymbolRefExpr::VK_PLT) &&
+          Target.getSymA()->getKind() == MCSymbolRefExpr::VK_PLT ||
+          Target.getSymA()->getKind() == MCSymbolRefExpr::VK_GOTPCREL) &&
          "Should only be expression-level modifiers here");
 
   assert((!Target.getSymB() ||
@@ -202,7 +203,9 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
     case FK_Data_2:
       return R_CLS(ABS16);
     case FK_Data_4:
-      return R_CLS(ABS32);
+      return Target.getAccessVariant() == MCSymbolRefExpr::VK_GOTPCREL
+                 ? R_CLS(GOTPCREL32)
+                 : R_CLS(ABS32);
     case FK_Data_8:
       if (IsILP32) {
         Ctx.reportError(Fixup.getLoc(),
diff --git a/llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s b/llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s
new file mode 100644
index 000000000000000..afbcaad9e1dfdcc
--- /dev/null
+++ b/llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s
@@ -0,0 +1,14 @@
+// RUN: llvm-mc -triple=aarch64 -filetype=obj %s -o - | \
+// RUN:   llvm-readobj -r - | FileCheck %s
+
+        .section .data
+this:
+        .word this@GOTPCREL
+        .word extern_sym@GOTPCREL+4
+        .word negative_offset@GOTPCREL-4
+
+// CHECK:      Section ({{.*}}) .rela.data
+// CHECK-NEXT:   0x0 R_AARCH64_GOTPCREL32 this 0x0
+// CHECK-NEXT:   0x4 R_AARCH64_GOTPCREL32 extern_sym 0x4
+// CHECK-NEXT:   0x8 R_AARCH64_GOTPCREL32 negative_offset 0xFFFFFFFFFFFFFFFC
+// CHECK-NEXT: }

llvmbot · 2023-11-16T23:19:59Z

@llvm/pr-subscribers-backend-aarch64

Author: None (PiJoules)

Changes

This is the follopw implementation to
ARM-software/abi-aa#223 that supports this relocation in llvm and lld.

Full diff: https://github.com/llvm/llvm-project/pull/72584.diff

5 Files Affected:

(modified) lld/ELF/Arch/AArch64.cpp (+3)
(added) lld/test/ELF/aarch64-reloc-gotpcrel32.s (+36)
(modified) llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def (+2)
(modified) llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp (+5-2)
(added) llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s (+14)

diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 048f0ec30ebd283..32cff73955028e4 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -165,6 +165,8 @@ RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
   case R_AARCH64_ADR_GOT_PAGE:
   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
     return R_AARCH64_GOT_PAGE_PC;
+  case R_AARCH64_GOTPCREL32:
+    return R_GOT_PC;
   case R_AARCH64_NONE:
     return R_NONE;
   default:
@@ -374,6 +376,7 @@ void AArch64::relocate(uint8_t *loc, const Relocation &rel,
     write32(loc, val);
     break;
   case R_AARCH64_PLT32:
+  case R_AARCH64_GOTPCREL32:
     checkInt(loc, val, 32, rel);
     write32(loc, val);
     break;
diff --git a/lld/test/ELF/aarch64-reloc-gotpcrel32.s b/lld/test/ELF/aarch64-reloc-gotpcrel32.s
new file mode 100644
index 000000000000000..7ea55bfc5b00aad
--- /dev/null
+++ b/lld/test/ELF/aarch64-reloc-gotpcrel32.s
@@ -0,0 +1,36 @@
+// REQUIRES: aarch64
+// RUN: llvm-mc -filetype=obj -triple=aarch64 %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=aarch64 %S/Inputs/abs255.s -o %t255.o
+// RUN: ld.lld %t.o -o %t.so -shared
+// RUN: llvm-readobj -S %t.so | FileCheck --check-prefix=SEC %s
+// RUN: llvm-objdump --no-print-imm-hex -s -d %t.so | FileCheck %s
+
+
+// SEC:         Name: .got (58)
+// SEC-NEXT:    Type: SHT_PROGBITS (0x1)
+// SEC-NEXT:    Flags [ (0x3)
+// SEC-NEXT:      SHF_ALLOC (0x2)
+// SEC-NEXT:      SHF_WRITE (0x1)
+// SEC-NEXT:    ]
+// SEC-NEXT:    Address: 0x20350
+// SEC-NEXT:    Offset: 0x350
+// SEC-NEXT:    Size: 8
+// SEC-NEXT:    Link: 0
+// SEC-NEXT:    Info: 0
+// SEC-NEXT:    AddressAlignment: 8
+// SEC-NEXT:    EntrySize: 0
+
+  .section .data
+  .globl bar
+bar:
+
+  .globl _start
+_start:
+// bar@GOTPCREL   = 0x20350 (got entry for `bar`) - 0x30358 (.) = 0xfffefff8
+// bar@GOTPCREL+4 = 0x20350 (got entry for `bar`) - 0x3035c (.) + 4 = 0xfffefff8
+// bar@GOTPCREL-4 = 0x20350 (got entry for `bar`) - 0x30360 (.) + 4 = 0xfffeffec
+// CHECK: Contents of section .data:
+// CHECK:  30358 f8fffeff f8fffeff ecfffeff
+  .word bar@GOTPCREL
+  .word bar@GOTPCREL+4
+  .word bar@GOTPCREL-4
diff --git a/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def b/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
index b507109b19e1b90..fcaea2aceed5209 100644
--- a/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
+++ b/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
@@ -59,6 +59,7 @@ ELF_RELOC(R_AARCH64_ADR_GOT_PAGE,                    0x137)
 ELF_RELOC(R_AARCH64_LD64_GOT_LO12_NC,                0x138)
 ELF_RELOC(R_AARCH64_LD64_GOTPAGE_LO15,               0x139)
 ELF_RELOC(R_AARCH64_PLT32,                           0x13a)
+ELF_RELOC(R_AARCH64_GOTPCREL32,                      0x13b)
 ELF_RELOC(R_AARCH64_TLSGD_ADR_PREL21,                0x200)
 ELF_RELOC(R_AARCH64_TLSGD_ADR_PAGE21,                0x201)
 ELF_RELOC(R_AARCH64_TLSGD_ADD_LO12_NC,               0x202)
@@ -166,6 +167,7 @@ ELF_RELOC(R_AARCH64_P32_ADR_GOT_PAGE,                0x01a)
 ELF_RELOC(R_AARCH64_P32_LD32_GOT_LO12_NC,            0x01b)
 ELF_RELOC(R_AARCH64_P32_LD32_GOTPAGE_LO14,           0x01c)
 ELF_RELOC(R_AARCH64_P32_PLT32,                       0x01d)
+ELF_RELOC(R_AARCH64_P32_GOTPCREL32,                  0x01e)
 ELF_RELOC(R_AARCH64_P32_TLSGD_ADR_PREL21,            0x050)
 ELF_RELOC(R_AARCH64_P32_TLSGD_ADR_PAGE21,            0x051)
 ELF_RELOC(R_AARCH64_P32_TLSGD_ADD_LO12_NC,           0x052)
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
index 9de40661298ccad..996fd1614d19f57 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
@@ -120,7 +120,8 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
 
   assert((!Target.getSymA() ||
           Target.getSymA()->getKind() == MCSymbolRefExpr::VK_None ||
-          Target.getSymA()->getKind() == MCSymbolRefExpr::VK_PLT) &&
+          Target.getSymA()->getKind() == MCSymbolRefExpr::VK_PLT ||
+          Target.getSymA()->getKind() == MCSymbolRefExpr::VK_GOTPCREL) &&
          "Should only be expression-level modifiers here");
 
   assert((!Target.getSymB() ||
@@ -202,7 +203,9 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
     case FK_Data_2:
       return R_CLS(ABS16);
     case FK_Data_4:
-      return R_CLS(ABS32);
+      return Target.getAccessVariant() == MCSymbolRefExpr::VK_GOTPCREL
+                 ? R_CLS(GOTPCREL32)
+                 : R_CLS(ABS32);
     case FK_Data_8:
       if (IsILP32) {
         Ctx.reportError(Fixup.getLoc(),
diff --git a/llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s b/llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s
new file mode 100644
index 000000000000000..afbcaad9e1dfdcc
--- /dev/null
+++ b/llvm/test/MC/AArch64/elf-reloc-gotpcrel32.s
@@ -0,0 +1,14 @@
+// RUN: llvm-mc -triple=aarch64 -filetype=obj %s -o - | \
+// RUN:   llvm-readobj -r - | FileCheck %s
+
+        .section .data
+this:
+        .word this@GOTPCREL
+        .word extern_sym@GOTPCREL+4
+        .word negative_offset@GOTPCREL-4
+
+// CHECK:      Section ({{.*}}) .rela.data
+// CHECK-NEXT:   0x0 R_AARCH64_GOTPCREL32 this 0x0
+// CHECK-NEXT:   0x4 R_AARCH64_GOTPCREL32 extern_sym 0x4
+// CHECK-NEXT:   0x8 R_AARCH64_GOTPCREL32 negative_offset 0xFFFFFFFFFFFFFFFC
+// CHECK-NEXT: }

PiJoules · 2023-11-16T23:23:08Z

I only discovered the R_AARCH64_P32_* relocations just now. Not sure if I need another rfc for R_AARCH64_P32_GOTPCREL32.

smithp35

Other than one line about the ILP32 code LGTM.

Please do tell us if you need ILP32 support and we can add the code to the ABI.

llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def

lld/test/ELF/aarch64-reloc-gotpcrel32.s

MaskRay · 2023-11-29T05:19:40Z

lld/test/ELF/aarch64-reloc-gotpcrel32-overflow.s

@@ -0,0 +1,11 @@
+// REQUIRES: aarch64


Newer tests place overflow tests (RUN: not ld.lld ...) and regular tests (RUN: ld.lld ...) in one file so that the boundary is clearer.

aarch64-reloc-plt32.s is a good example

For PLT32 I can put all the tests in one file since foo@PLT can be relaxed to foo if it's defined in one of the other input files, but I don't think the same can work for foo@GOTPCREL since this can't be relaxed to anything that could be defined in a separate input file.

Do you perhaps have another example I can follow?

Perhaps you can use more than one symbol in a test.

Since the error message contains the bounds (in [-2147483648, 2147483647]), I think we don't need to make an extreme test.

Updated tests

smithp35 · 2023-11-29T09:53:52Z

I don't have any more comments, thanks for making the earlier changes. Happy for MaskRay to approve when his comments have been addressed.

lld/test/ELF/aarch64-reloc-gotpcrel32.s

MaskRay

I think this is mostly good, just needing some test changes.

This is the follopw implementation to ARM-software/abi-aa#223 that supports this relocation in llvm and lld.

This reverts the MC changes from commit 04a906e, which cause failures when linking with gold on arm64.

Partially revert "[llvm][lld] Support R_AARCH64_GOTPCREL32 (llvm#72584)"

…lvm#72584)"" This reverts commit f1cbfe9, which ended up causing other failures.

Revert "Partially revert "[llvm][lld] Support R_AARCH64_GOTPCREL32 (llvm#72584)""

dianqk · 2025-05-31T12:39:48Z

We have identified that some Rust projects are broken from here, such as rust-lang/rust#141737 and tikv/tikv#18465. Can we revert this until the GNU linker also supports R_AARCH64_GOTPCREL32?

nikic · 2025-05-31T14:46:05Z

We have identified that some Rust projects are broken from here, such as rust-lang/rust#141737 and tikv/tikv#18465. Can we revert this until the GNU linker also supports R_AARCH64_GOTPCREL32?

You're suggesting to only revert the AArch64ELFObjectWriter part, right?

MaskRay · 2025-05-31T18:05:27Z

We have identified that some Rust projects are broken from here, such as rust-lang/rust#141737 and tikv/tikv#18465. Can we revert this until the GNU linker also supports R_AARCH64_GOTPCREL32?

I don't think it's reasonable to request reverting the lld/ELF or AArch64 assembler changes. The affected code path is only used when the input IR is in a specific form. If Rust needs compatibility with GNU ld or older lld, it should stop emitting IR that triggers this path.

Additionally, the linked rust-lang/rust#141737 does not explain why you assert this is an LLVM issue rather than a Rust one.

nikic · 2025-05-31T19:00:19Z

@MaskRay Rust is not generating this pattern, LLVM is. Are you suggesting that the RelLookupTableConverter pass should be disabled on aarch64?

dianqk · 2025-05-31T19:25:40Z

@MaskRay Rust is not generating this pattern, LLVM is. Are you suggesting that the RelLookupTableConverter pass should be disabled on aarch64?

Just a question: is it reasonable, like https://github.com/rust-lang/llvm-project/pull/181/files removes unnamed_addr in the RelLookupTableConverter pass? I don't see any problem with retaining unnamed_addr on IR.

MaskRay · 2025-05-31T19:42:42Z

I don't have a Rust development environment, but these components are likely involved:

Rust LLVM IR producer
llvm/lib/Transforms/Utils/RelLookupTableConverter.cpp
llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:handleIndirectSymViaGOTPCRel This converts GOT-equivalent Constant uses to GOTPCREL style fixups.
llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp lowers GOTPCREL style fixups to relocations, where R_AARCH64_GOTPCREL32 is not supported by GNU ld or older LLD.

Implementing a workaround in LLVM's Transforms or CodeGen sections might seem appealing for broader IR producer support, but we generally aim to avoid adding linker compatibility checks...
I'm currently leaning towards Rust implementing the workaround within its IR producer...

nikic · 2025-05-31T19:44:54Z

@MaskRay Rust is not generating this pattern, LLVM is. Are you suggesting that the RelLookupTableConverter pass should be disabled on aarch64?

Just a question: is it reasonable, like https://github.com/rust-lang/llvm-project/pull/181/files removes unnamed_addr in the RelLookupTableConverter pass? I don't see any problem with retaining unnamed_addr on IR.

It looks like removing unnamed_addr avoids the use of the GOTPCREL relocations: https://llvm.godbolt.org/z/js9vx39ar

nikic · 2025-05-31T20:10:13Z

@MaskRay I don't think this can be worked around by changing the IR Rust produces. The IR that Rust generates is very boring. All the decisions that ultimately lead to the use of this unsupported relocation are made by LLVM, so this needs to be fixed in LLVM, either by not using this relocation at all, or by never producing IR that can lead to the use of this relocation. The former seems cleaner to me, but I'm ok with either variant.

MaskRay · 2025-05-31T21:24:00Z

Disabling RelLookupTableConverter.cpp looks good to me. It's a tradeoff between dynamic relocations/startup time and slightly more instructions at the single user.

nikic · 2025-05-31T21:28:37Z

Okay, in that case I think doing something along the lines of @dianqk's workaround in https://github.com/rust-lang/llvm-project/pull/181/files would be best. That allows RelLookupTableConverter to still generally work, but prevents it from generating GOTPCREL relocations.

…REL relocations (#142304) Follow #72584 (comment), the patch will drop the `unnamed_addr` attribute when generating relative lookup tables. I'm not very confident about this patch, but it does resolve rust-lang/rust#140686, rust-lang/rust#141306 and rust-lang/rust#141737. But I don't think this will result in worse problems. > LLVM provides that the calculation of such a constant initializer will not overflow at link time under the medium code model if x is an unnamed_addr function. However, it does not provide this guarantee for a constant initializer folded into a function body. This intrinsic can be used to avoid the possibility of overflows when loading from such a constant. ([‘llvm.load.relative’ Intrinsic](https://llvm.org/docs/LangRef.html#id2592)) This is my concern. I'm not sure how unnamed_addr provides this guarantee, and I haven't found any test cases.

…ating GOTPCREL relocations (#142304) Follow llvm/llvm-project#72584 (comment), the patch will drop the `unnamed_addr` attribute when generating relative lookup tables. I'm not very confident about this patch, but it does resolve rust-lang/rust#140686, rust-lang/rust#141306 and rust-lang/rust#141737. But I don't think this will result in worse problems. > LLVM provides that the calculation of such a constant initializer will not overflow at link time under the medium code model if x is an unnamed_addr function. However, it does not provide this guarantee for a constant initializer folded into a function body. This intrinsic can be used to avoid the possibility of overflows when loading from such a constant. ([‘llvm.load.relative’ Intrinsic](https://llvm.org/docs/LangRef.html#id2592)) This is my concern. I'm not sure how unnamed_addr provides this guarantee, and I haven't found any test cases.

…REL relocations (llvm#142304) Follow llvm#72584 (comment), the patch will drop the `unnamed_addr` attribute when generating relative lookup tables. I'm not very confident about this patch, but it does resolve rust-lang/rust#140686, rust-lang/rust#141306 and rust-lang/rust#141737. But I don't think this will result in worse problems. > LLVM provides that the calculation of such a constant initializer will not overflow at link time under the medium code model if x is an unnamed_addr function. However, it does not provide this guarantee for a constant initializer folded into a function body. This intrinsic can be used to avoid the possibility of overflows when loading from such a constant. ([‘llvm.load.relative’ Intrinsic](https://llvm.org/docs/LangRef.html#id2592)) This is my concern. I'm not sure how unnamed_addr provides this guarantee, and I haven't found any test cases. (cherry picked from commit aa09dbb)

…ating GOTPCREL relocations (#142304) Follow llvm/llvm-project#72584 (comment), the patch will drop the `unnamed_addr` attribute when generating relative lookup tables. I'm not very confident about this patch, but it does resolve rust-lang/rust#140686, rust-lang/rust#141306 and rust-lang/rust#141737. But I don't think this will result in worse problems. > LLVM provides that the calculation of such a constant initializer will not overflow at link time under the medium code model if x is an unnamed_addr function. However, it does not provide this guarantee for a constant initializer folded into a function body. This intrinsic can be used to avoid the possibility of overflows when loading from such a constant. ([‘llvm.load.relative’ Intrinsic](https://llvm.org/docs/LangRef.html#id2592)) This is my concern. I'm not sure how unnamed_addr provides this guarantee, and I haven't found any test cases. (cherry picked from commit aa09dbb)

…REL relocations (llvm#142304) Follow llvm#72584 (comment), the patch will drop the `unnamed_addr` attribute when generating relative lookup tables. I'm not very confident about this patch, but it does resolve rust-lang/rust#140686, rust-lang/rust#141306 and rust-lang/rust#141737. But I don't think this will result in worse problems. > LLVM provides that the calculation of such a constant initializer will not overflow at link time under the medium code model if x is an unnamed_addr function. However, it does not provide this guarantee for a constant initializer folded into a function body. This intrinsic can be used to avoid the possibility of overflows when loading from such a constant. ([‘llvm.load.relative’ Intrinsic](https://llvm.org/docs/LangRef.html#id2592)) This is my concern. I'm not sure how unnamed_addr provides this guarantee, and I haven't found any test cases.

llvmbot added lld backend:AArch64 mc Machine (object) code lld:ELF llvm:binary-utilities labels Nov 16, 2023

PiJoules requested review from petrhosek, MaskRay and smithp35 November 16, 2023 23:19

PiJoules force-pushed the aarch64-gotpcrel32 branch from a0b6255 to 958ec66 Compare November 17, 2023 00:08

smithp35 reviewed Nov 20, 2023

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MaskRay mentioned this pull request Nov 22, 2023

[llvm][lld] Support R_RISCV_GOT32_PCREL #72587

Merged

MaskRay changed the title ~~[llvm][lld] Support R_<CLS>_GOTREL32~~ [llvm][lld] Support R_AARCH64_GOTPCREL32 Nov 27, 2023

PiJoules force-pushed the aarch64-gotpcrel32 branch from 958ec66 to 718b1c5 Compare November 29, 2023 00:02

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PiJoules requested a review from MaskRay November 29, 2023 19:24

MaskRay reviewed Dec 7, 2023

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PiJoules force-pushed the aarch64-gotpcrel32 branch from 718b1c5 to 2353935 Compare January 10, 2024 20:11

[llvm][lld] Support R_<CLS>_GOTREL32

43a19d6

This is the follopw implementation to ARM-software/abi-aa#223 that supports this relocation in llvm and lld.

PiJoules force-pushed the aarch64-gotpcrel32 branch from 2353935 to 43a19d6 Compare January 10, 2024 20:41

MaskRay approved these changes Jan 10, 2024

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PiJoules merged commit 04a906e into llvm:main Jan 10, 2024

justinfargnoli pushed a commit to justinfargnoli/llvm-project that referenced this pull request Jan 28, 2024

[llvm][lld] Support R_AARCH64_GOTPCREL32 (llvm#72584)

b6d2121

This is the follopw implementation to ARM-software/abi-aa#223 that supports this relocation in llvm and lld.

smeenai mentioned this pull request Feb 15, 2024

[aaelf64] Define GOT-Relative data relocation ARM-software/abi-aa#223

Merged

bnbarham added a commit to bnbarham/llvm-project that referenced this pull request Sep 24, 2024

Partially revert "[llvm][lld] Support R_AARCH64_GOTPCREL32 (llvm#72584)"

f1cbfe9

This reverts the MC changes from commit 04a906e, which cause failures when linking with gold on arm64.

bnbarham added a commit to swiftlang/llvm-project that referenced this pull request Sep 25, 2024

Merge pull request #9288 from bnbarham/revert-gotpcrel32

e4b1c45

Partially revert "[llvm][lld] Support R_AARCH64_GOTPCREL32 (llvm#72584)"

bnbarham added a commit to bnbarham/llvm-project that referenced this pull request Sep 26, 2024

Revert "Partially revert "[llvm][lld] Support R_AARCH64_GOTPCREL32 (l…

a6cc36b

…lvm#72584)"" This reverts commit f1cbfe9, which ended up causing other failures.

bnbarham added a commit to swiftlang/llvm-project that referenced this pull request Sep 26, 2024

Merge pull request #9341 from bnbarham/revert-crel-revert

db1d216

Revert "Partially revert "[llvm][lld] Support R_AARCH64_GOTPCREL32 (llvm#72584)""

MaskRay mentioned this pull request Mar 22, 2025

[AArch64] Assembly syntax for relocation specifier in data directives #132570

Open

dianqk mentioned this pull request May 31, 2025

Enabling LTO causes miscompilation on x86_64-apple-darwin rust-lang/rust#141306

Closed

dianqk mentioned this pull request Jun 1, 2025

[RelLookupTableConverter] Drop unnamed_addr to avoid generating GOTPCREL relocations #142304

Merged

[llvm][lld] Support R_AARCH64_GOTPCREL32 #72584

[llvm][lld] Support R_AARCH64_GOTPCREL32 #72584

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