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llvm-project/lld/test/ELF/arm-undefined-weak.s

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[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
// RUN: llvm-mc -filetype=obj -triple=armv7a-none-linux-gnueabi %s -o %t
// RUN: ld.lld %t -o %t2 2>&1
// RUN: llvm-objdump -triple=armv7a-none-linux-gnueabi -d %t2 | FileCheck %s
// REQUIRES: arm
// Check that the ARM ABI rules for undefined weak symbols are applied.
// Branch instructions are resolved to the next instruction. Undefined
// Symbols in relative are resolved to the place so S - P + A = A.
.syntax unified
.weak target
.text
.global _start
_start:
// R_ARM_JUMP24
b target
// R_ARM_CALL
bl target
// R_ARM_CALL with exchange
blx target
// R_ARM_MOVT_PREL
movt r0, :upper16:target - .
// R_ARM_MOVW_PREL_NC
movw r0, :lower16:target - .
// R_ARM_REL32
.word target - .
// CHECK: Disassembly of section .text:
// 69636 = 0x11004
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: {{.*}} b #-4 <_start+0x4>
// CHECK-NEXT: 11004: {{.*}} bl #-4 <_start+0x8>
[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
// blx is transformed into bl so we don't change state
Update lld tests after r321526. llvm-svn: 321529
2017-12-29 01:20:41 +08:00
// CHECK-NEXT: 11008: {{.*}} bl #-4 <_start+0xc>
Don't check the raw bits in tests. It is not needed since we have the disassemble. llvm-svn: 305096
2017-06-10 02:07:34 +08:00
// CHECK-NEXT: 1100c: {{.*}} movt r0, #0
// CHECK-NEXT: 11010: {{.*}} movw r0, #0
// CHECK: 11014: {{.*}} .word 0x00000000
[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