[llvm] [llvm] Indirect symbol replacement with GOTPCREL for aarch64 and risc… (PR #78003)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: None (PiJoules)

<details>
<summary>Changes</summary>

…v64 ELF

This is similar to https://github.com/llvm/llvm-project/pull/67754 but adds support for ELF aarch64 and riscv64 now that GOTPCREL-equivalent relocations have been added for those archs.

---
Full diff: https://github.com/llvm/llvm-project/pull/78003.diff


5 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp (+10) 
- (modified) llvm/lib/Target/AArch64/AArch64TargetObjectFile.h (+7) 
- (modified) llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp (+12) 
- (modified) llvm/lib/Target/RISCV/RISCVTargetObjectFile.h (+6) 
- (modified) llvm/test/MC/ELF/rtti-proxy-gotpcrel.ll (+3-1) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
index 7ed934cfabc0d5..e5c6b6d60d068d 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
@@ -25,6 +25,16 @@ void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx,
   SupportDebugThreadLocalLocation = false;
 }
 
+const MCExpr *AArch64_ELFTargetObjectFile::getIndirectSymViaGOTPCRel(
+    const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
+    int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+  int64_t FinalOffset = Offset + MV.getConstant();
+  const MCExpr *Res =
+      MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
+  const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext());
+  return MCBinaryExpr::createAdd(Res, Off, getContext());
+}
+
 AArch64_MachoTargetObjectFile::AArch64_MachoTargetObjectFile() {
   SupportGOTPCRelWithOffset = false;
 }
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
index 9f098230bbd78f..7cd56fc9a189d8 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
@@ -21,7 +21,14 @@ class AArch64_ELFTargetObjectFile : public TargetLoweringObjectFileELF {
 public:
   AArch64_ELFTargetObjectFile() {
     PLTRelativeVariantKind = MCSymbolRefExpr::VK_PLT;
+    SupportIndirectSymViaGOTPCRel = true;
   }
+
+  const MCExpr *getIndirectSymViaGOTPCRel(const GlobalValue *GV,
+                                          const MCSymbol *Sym,
+                                          const MCValue &MV, int64_t Offset,
+                                          MachineModuleInfo *MMI,
+                                          MCStreamer &Streamer) const override;
 };
 
 /// AArch64_MachoTargetObjectFile - This TLOF implementation is used for Darwin.
diff --git a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
index 7c9e57e6eef3ce..1535149b919b55 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
@@ -12,6 +12,7 @@
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCValue.h"
 
 using namespace llvm;
 
@@ -25,6 +26,7 @@ void RISCVELFTargetObjectFile::Initialize(MCContext &Ctx,
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
 
   PLTRelativeVariantKind = MCSymbolRefExpr::VK_PLT;
+  SupportIndirectSymViaGOTPCRel = true;
 
   SmallDataSection = getContext().getELFSection(
       ".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
@@ -32,6 +34,16 @@ void RISCVELFTargetObjectFile::Initialize(MCContext &Ctx,
                                                ELF::SHF_WRITE | ELF::SHF_ALLOC);
 }
 
+const MCExpr *RISCVELFTargetObjectFile::getIndirectSymViaGOTPCRel(
+    const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
+    int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+  int64_t FinalOffset = Offset + MV.getConstant();
+  const MCExpr *Res =
+      MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
+  const MCExpr *Off = MCConstantExpr::create(FinalOffset, getContext());
+  return MCBinaryExpr::createAdd(Res, Off, getContext());
+}
+
 // A address must be loaded from a small section if its size is less than the
 // small section size threshold. Data in this section could be addressed by
 // using gp_rel operator.
diff --git a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h
index 890effd07320a6..0910fbd3d95041 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h
+++ b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.h
@@ -42,6 +42,12 @@ class RISCVELFTargetObjectFile : public TargetLoweringObjectFileELF {
   void getModuleMetadata(Module &M) override;
 
   bool isInSmallSection(uint64_t Size) const;
+
+  const MCExpr *getIndirectSymViaGOTPCRel(const GlobalValue *GV,
+                                          const MCSymbol *Sym,
+                                          const MCValue &MV, int64_t Offset,
+                                          MachineModuleInfo *MMI,
+                                          MCStreamer &Streamer) const override;
 };
 
 } // end namespace llvm
diff --git a/llvm/test/MC/ELF/rtti-proxy-gotpcrel.ll b/llvm/test/MC/ELF/rtti-proxy-gotpcrel.ll
index c58bb5b77c6c5d..b6d6633e7cad95 100644
--- a/llvm/test/MC/ELF/rtti-proxy-gotpcrel.ll
+++ b/llvm/test/MC/ELF/rtti-proxy-gotpcrel.ll
@@ -1,4 +1,6 @@
-; RUN: llc %s -mtriple=x86_64-unknown-fuchsia  -o - | FileCheck %s
+; RUN: llc %s -mtriple=x86_64-unknown-fuchsia -o - | FileCheck %s
+; RUN: llc %s -mtriple=aarch64-unknown-fuchsia -o - | FileCheck %s
+; RUN: llc %s -mtriple=riscv64-unknown-fuchsia -o - | FileCheck %s
 
 @vtable = dso_local unnamed_addr constant i32 trunc (i64 sub (i64 ptrtoint (ptr @rtti.proxy to i64), i64 ptrtoint (ptr @vtable to i64)) to i32), align 4
 @vtable_with_offset = dso_local unnamed_addr constant [2 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @rtti.proxy to i64), i64 ptrtoint (ptr @vtable_with_offset to i64)) to i32)], align 4

``````````

</details>


https://github.com/llvm/llvm-project/pull/78003