[JITLink][ELF/AARCH64] Implement eh frame handling

[sunho]

Summary

This patch implements eh frame handling by using generic EHFrame passes. I checked that c++ exception handling works correctly with this change. (it doens't work without this change)

[lhames]

LGTM. Thanks @sunho!

llvm/lib/ExecutionEngine/JITLink/ELF_aarch64.cpp

 //===----- ELF_aarch64.cpp - JIT linker implementation for ELF/aarch64 ----===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // ELF/aarch64 jit-link implementation.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/JITLink/ELF_aarch64.h"
+#include "EHFrameSupportImpl.h"
 #include "ELFLinkGraphBuilder.h"
 #include "JITLinkGeneric.h"
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/ExecutionEngine/JITLink/DWARFRecordSectionSplitter.h"
 #include "llvm/ExecutionEngine/JITLink/aarch64.h"
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/MathExtras.h"
 
 #include "PerGraphGOTAndPLTStubsBuilder.h"
 
 #define DEBUG_TYPE "jitlink"
return ELFLinkGraphBuilder_aarch64<object::ELF64LE>((*ELFObj)->getFileName(),
       .buildGraph();
 }
 
 void link_ELF_aarch64(std::unique_ptr<LinkGraph> G,
                       std::unique_ptr<JITLinkContext> Ctx) {
   PassConfiguration Config;
   const Triple &TT = G->getTargetTriple();
   if (Ctx->shouldAddDefaultTargetPasses(TT)) {
+    Config.PrePrunePasses.push_back(DWARFRecordSectionSplitter(".eh_frame"));
+    Config.PrePrunePasses.push_back(EHFrameEdgeFixer(
+        ".eh_frame", 8, aarch64::Pointer32, aarch64::Pointer64,
+        aarch64::Delta32, aarch64::Delta64, aarch64::NegDelta32));
     if (auto MarkLive = Ctx->getMarkLivePass(TT))
       Config.PrePrunePasses.push_back(std::move(MarkLive));
     else
       Config.PrePrunePasses.push_back(markAllSymbolsLive);
   }
 
   Config.PostPrunePasses.push_back(
       PerGraphGOTAndPLTStubsBuilder_ELF_arm64::asPass);

llvm/test/ExecutionEngine/JITLink/AArch64/ELF_aarch64_ehframe.s

+# REQUIRES: asserts
+# RUN: llvm-mc -triple=aarch64-linux-gnu -filetype=obj -o %t %s
+# RUN: llvm-jitlink -noexec -phony-externals -debug-only=jitlink %t 2>&1 | \
+# RUN:   FileCheck %s
+#
+# Check that splitting of eh-frame sections works.
+#
+# CHECK: DWARFRecordSectionSplitter: Processing .eh_frame...
+# CHECK:  Processing block at
+# CHECK:    Processing CFI record at
+# CHECK:      Extracted {{.*}} section = .eh_frame
+# CHECK:    Processing CFI record at
+# CHECK:      Extracted {{.*}} section = .eh_frame
+# CHECK: EHFrameEdgeFixer: Processing .eh_frame...
+# CHECK:   Processing block at
+# CHECK:     Processing CFI record at
+# CHECK:       Record is CIE
+# CHECK:   Processing block at
+# CHECK:     Processing CFI record at
+# CHECK:       Record is FDE
+# CHECK:         Adding edge at {{.*}} to CIE at: {{.*}}
+# CHECK:         Existing edge at {{.*}} to PC begin at {{.*}}
+# CHECK:         Adding keep-alive edge from target at {{.*}} to FDE at {{.*}}
+# CHECK:   Processing block at
+# CHECK:     Processing CFI record at
+# CHECK:       Record is FDE
+# CHECK:         Adding edge at {{.*}} to CIE at: {{.*}}
+# CHECK:         Existing edge at {{.*}} to PC begin at {{.*}}
+# CHECK:         Adding keep-alive edge from target at {{.*}} to FDE at {{.*}}
+
+  .text
+  .globl  main
+  .p2align  2
+  .type main,@function
+main: 
+  .cfi_startproc
+  sub sp, sp, #32
+  .cfi_def_cfa_offset 32
+  stp  x29, x30, [sp, #16]
+  add x29, sp, #16
+  .cfi_def_cfa w29, 16
+  .cfi_offset w30, -8
+  .cfi_offset w29, -16
+  stur  wzr, [x29, #-4]
+  mov x0, #4
+  bl  __cxa_allocate_exception
+  mov w8, #1
+  str w8, [x0]
+  adrp  x1, :got:_ZTIi
+  ldr  x1, [x1, :got_lo12:_ZTIi]
+  mov x2, xzr
+  bl  __cxa_throw
+.main_end:
+  .size main, .main_end-main
+  .cfi_endproc
+
+  .globl  dup
+  .p2align  2
+  .type dup,@function
+dup: 
+  .cfi_startproc
+  sub sp, sp, #32
+  .cfi_def_cfa_offset 32
+  stp  x29, x30, [sp, #16]
+  add x29, sp, #16
+  .cfi_def_cfa w29, 16
+  .cfi_offset w30, -8
+  .cfi_offset w29, -16
+  stur  wzr, [x29, #-4]
+  mov x0, #4
+  bl  __cxa_allocate_exception
+  mov w8, #1
+  str w8, [x0]
+  adrp  x1, :got:_ZTIi
+  ldr  x1, [x1, :got_lo12:_ZTIi]
+  mov x2, xzr
+  bl  __cxa_throw
+.dup_end:
+  .size dup, .dup_end-dup
+  .cfi_endproc
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