Commit f2ee78cc authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r344264: 

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r344264 | mstorsjo | 2018-10-11 10:45:51 -0700 (Thu, 11 Oct 2018) | 8 lines

[COFF] Set proper pointer size alignment for LocalImportChunk

When these are accessed with load/store instructions on ARM64,
it becomes strictly necessary to have them properly aligned.

This fixes PR39228.

Differential Revision: https://reviews.llvm.org/D53128
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llvm-svn: 344920
parent dfebe573

lld/COFF/Chunks.h

+3 −1
Original line number Diff line number Diff line
@@ -345,7 +345,9 @@ private: 
// See comments for DefinedLocalImport class.

class LocalImportChunk : public Chunk {

public:

  explicit LocalImportChunk(Defined *S) : Sym(S) {}

  explicit LocalImportChunk(Defined *S) : Sym(S) {

    Alignment = Config->is64() ? 8 : 4;

  }

  size_t getSize() const override;

  void getBaserels(std::vector<Baserel> *Res) override;

  void writeTo(uint8_t *Buf) const override;

lld/test/COFF/arm64-localimport-align.s

0 → 100644
+24 −0
Original line number Diff line number Diff line 
// REQUIRES: aarch64

// RUN: llvm-mc -filetype=obj -triple=aarch64-windows %s -o %t.obj

// RUN: lld-link -entry:main -subsystem:console %t.obj -out:%t.exe

// Don't check the output, just make sure it links fine and doesn't

// error out due to a misaligned load.

    .text

    .globl main

    .globl myfunc

main:

    adrp x8, __imp_myfunc

    ldr  x0, [x8, :lo12:__imp_myfunc]

    br   x0

    ret

myfunc:

    ret



    .section .rdata, "dr"

    // Start the .rdata section with a 4 byte chunk, to expose the alignment

    // of the next chunk in the section.

mydata:

    .byte 42

    // The synthesized LocalImportChunk gets stored here in the .rdata

    // section, but needs to get proper 8 byte alignment since it is a

    // pointer, just like regular LookupChunks in the IAT.