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llvm-project/lld/test/ELF/arm-thumb-no-undefined-thunk.s

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[ELF] Do not create interworking thunks for undefined weak references. An undefined weak reference is given an address of 0 this will incorrectly trigger the creation of a Thumb to ARM interworking Thunk if there is a Thumb branch instruction to the symbol. This results in an error as Thunks only make sense to defined or shared symbols. We prevent this by detecting an undefined symbol and not creating a thunk for it. Differential Revision: https://reviews.llvm.org/D26239 llvm-svn: 285896
2016-11-03 19:49:23 +08:00
// RUN: llvm-mc -filetype=obj -triple=thumbv7a-none-linux-gnueabi %s -o %t
// RUN: ld.lld %t -o %t2 2>&1
// RUN: llvm-objdump -triple=thumbv7a-none-linux-gnueabi -d %t2 | FileCheck %s
// REQUIRES: arm
// Check that no thunks are created for an undefined weak symbol
.syntax unified
.weak target
.section .text.thumb, "ax", %progbits
.thumb
.global
_start:
bl target
b target
b.w target
// CHECK: Disassembly of section .text:
// CHECK-NEXT: _start:
[ELF] ARM and AArch64 undefined weak reference values The ARM 32 and 64-bit ABI does not use 0 for undefined weak references that are used in PC relative relocations. In particular: - A branch relocation to an undefined weak resolves to the next instruction. Effectively making the branch a no-op - In all other cases the symbol resolves to the place so that S + A - P resolves to A. Differential Revision: https://reviews.llvm.org/D26240 llvm-svn: 286353
2016-11-09 18:22:29 +08:00
// 69636 = 0x11004 = next instruction
Fix weak symbols on arm and aarch64. Given .weak target .global _start _start: b target The intention is that the branch goes to the instruction after the branch, effectively turning it on a nop. The branch adds the runtime PC, but we were adding it statically too. I noticed the oddity by inspection, but llvm-objdump seems to agree, since it now prints things like: b #-4 <_start+0x4> llvm-svn: 305212
2017-06-13 02:05:01 +08:00
// CHECK: 11000: {{.*}} bl #0
// CHECK-NEXT: 11004: {{.*}} b.w #0 <_start+0x8>
Update lld tests after r321526. llvm-svn: 321529
2017-12-29 01:20:41 +08:00
// CHECK-NEXT: 11008: {{.*}} b.w #0 <_start+0xc>