Commit 4ebe62d3 authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r359094: 

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r359094 | maskray | 2019-04-24 07:03:30 -0700 (Wed, 24 Apr 2019) | 12 lines

[PPC64] Consider localentry offset when computing branch distance

Summary:
We don't take localentry offset into account, and thus may fail to
create a long branch when the gap is just a few bytes smaller than 2^25.

relocation R_PPC64_REL24 out of range: 33554432 is not in [-33554432, 33554431]
relocation R_PPC64_REL24 out of range: 33554436 is not in [-33554432, 33554431]

Fix that by adding the offset to the symbol VA.

Differential Revision: https://reviews.llvm.org/D61058
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llvm-svn: 364209
parent c2be2080

lld/ELF/Arch/PPC64.cpp

+4 −1
Original line number Diff line number Diff line
@@ -757,7 +757,10 @@ bool PPC64::needsThunk(RelExpr Expr, RelType Type, const InputFile *File, 


  // If the offset exceeds the range of the branch type then it will need

  // a range-extending thunk.

  return !inBranchRange(Type, BranchAddr, S.getVA());

  // See the comment in getRelocTargetVA() about R_PPC64_CALL.

  return !inBranchRange(Type, BranchAddr,

                        S.getVA() +

                            getPPC64GlobalEntryToLocalEntryOffset(S.StOther));

}



uint32_t PPC64::getThunkSectionSpacing() const {

lld/test/ELF/ppc64-long-branch-localentry-offset.s

0 → 100644
+30 −0
Original line number Diff line number Diff line 
# REQUIRES: ppc



# RUN: llvm-mc -filetype=obj -triple=ppc64le %s -o %t.o

# RUN: ld.lld %t.o -o %t

# RUN: llvm-nm %t | FileCheck %s



# CHECK-DAG: 0000000010010000 t __long_branch_callee

# CHECK-DAG: 0000000010010010 T _start

# CHECK-DAG: 0000000012010008 T callee



# The bl instruction jumps to the local entry. The distance requires a long branch stub:

# localentry(callee) - _start = 0x12010008+8 - 0x10010010 = 0x2000000



# We used to compute globalentry(callee) - _start and caused a "R_PPC64_REL24

# out of range" error because we didn't create the stub.



.globl _start

_start:

  bl callee



.space 0x1fffff4



.globl callee

callee:

.Lgep0:

  addis 2, 12, .TOC.-.Lgep0@ha

  addi 2, 2, .TOC.-.Lgep0@l

.Llep0:

  .localentry callee, .Llep0-.Lgep0

  blr