[PATCH] D143226: [MC][CodeGen] Define R_RISCV_PLT32 and lower dso_local_equivalent to it

[Leonard Chan via Phabricator via llvm-commits]

leonardchan updated this revision to Diff 495953.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D143226/new/

https://reviews.llvm.org/D143226

Files:
  llvm/include/llvm/BinaryFormat/ELFRelocs/RISCV.def
  llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
  llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
  llvm/test/CodeGen/RISCV/dso_local_equivalent.ll
  llvm/test/MC/RISCV/elf-reloc-plt32.s


Index: llvm/test/MC/RISCV/elf-reloc-plt32.s
===================================================================
--- /dev/null
+++ llvm/test/MC/RISCV/elf-reloc-plt32.s
@@ -0,0 +1,11 @@
+# RUN: llvm-mc -triple=riscv64 -filetype=obj %s -o - \
+# RUN:   | llvm-readobj -r - | FileCheck %s
+# RUN: llvm-mc -triple=riscv32 -filetype=obj %s -o - \
+# RUN:   | llvm-readobj -r - | FileCheck %s
+
+.data
+.word extern_func at PLT - . + 4
+
+# CHECK:      Section ({{.*}}) .rela.data {
+# CHECK-NEXT:   0x0 R_RISCV_PLT32 extern_func 0x4
+# CHECK-NEXT: }
Index: llvm/test/CodeGen/RISCV/dso_local_equivalent.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/RISCV/dso_local_equivalent.ll
@@ -0,0 +1,12 @@
+; RUN: llc -mtriple=riscv64 < %s | FileCheck %s --match-full-lines
+; RUN: llc -mtriple=riscv32 < %s | FileCheck %s --match-full-lines
+
+declare void @extern_func()
+
+; CHECK-LABEL: const:
+; CHECK-NEXT:    .word   extern_func at PLT-const
+
+;; Note that for riscv32, the ptrtoint will actually upcast the ptr it to an
+;; oversized 64-bit pointer that eventually gets truncated. This isn't needed
+;; for riscv32, but this unifies the RV64 and RV32 test cases.
+ at const = dso_local constant i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @extern_func to i64), i64 ptrtoint (ptr @const to i64)) to i32)
Index: llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
+++ llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
@@ -18,6 +18,8 @@
                                           const TargetMachine &TM) {
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
 
+  PLTRelativeVariantKind = MCSymbolRefExpr::VK_PLT;
+
   SmallDataSection = getContext().getELFSection(
       ".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
   SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
Index: llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
===================================================================
--- llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
+++ llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
@@ -13,6 +13,7 @@
 #include "llvm/MC/MCELFObjectWriter.h"
 #include "llvm/MC/MCFixup.h"
 #include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCValue.h"
 #include "llvm/Support/ErrorHandling.h"
 
 using namespace llvm;
@@ -61,7 +62,9 @@
       return ELF::R_RISCV_NONE;
     case FK_Data_4:
     case FK_PCRel_4:
-      return ELF::R_RISCV_32_PCREL;
+      return Target.getAccessVariant() == MCSymbolRefExpr::VK_PLT
+                 ? ELF::R_RISCV_PLT32
+                 : ELF::R_RISCV_32_PCREL;
     case RISCV::fixup_riscv_pcrel_hi20:
       return ELF::R_RISCV_PCREL_HI20;
     case RISCV::fixup_riscv_pcrel_lo12_i:
Index: llvm/include/llvm/BinaryFormat/ELFRelocs/RISCV.def
===================================================================
--- llvm/include/llvm/BinaryFormat/ELFRelocs/RISCV.def
+++ llvm/include/llvm/BinaryFormat/ELFRelocs/RISCV.def
@@ -54,3 +54,4 @@
 ELF_RELOC(R_RISCV_SET32,             56)
 ELF_RELOC(R_RISCV_32_PCREL,          57)
 ELF_RELOC(R_RISCV_IRELATIVE,         58)
+ELF_RELOC(R_RISCV_PLT32,             59)


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