a8656c62f5
Older Arm architectures do not support the MOVT and MOVW instructions so we must use an alternative sequence of instructions to transfer control to the destination. Assuming at least Armv5 this patch adds support for Thunks that load or add to the program counter. Note that there are no Armv5 Thumb Thunks as there is no Thumb branch instruction in Armv5 that supports Thunks. These thunks will not work for Armv4t (arm7tdmi) as this architecture cannot change state from using the LDR or ADD instruction. Differential Revision: https://reviews.llvm.org/D50077 llvm-svn: 340160
56 lines
2.3 KiB
ArmAsm
56 lines
2.3 KiB
ArmAsm
// REQUIRES: arm
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// RUN: llvm-mc -arm-add-build-attributes -filetype=obj -triple=thumbv7a-none-linux-gnueabi %s -o %t
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// RUN: ld.lld %t --shared -o %t.so
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// RUN: llvm-objdump -d -triple=thumbv7a-none-linux-gnueabi %t.so | FileCheck %s
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// RUN: llvm-objdump -d -triple=armv7a-none-linux-gnueabi %t.so | FileCheck %s -check-prefix=PLT
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.syntax unified
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.global sym1
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.global elsewhere
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.weak weakref
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sym1:
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b.w elsewhere
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b.w weakref
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// Check that we generate a thunk for an undefined symbol called via a plt
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// entry.
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// CHECK: Disassembly of section .text:
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// CHECK-NEXT: sym1:
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// CHECK-NEXT: 1000: 00 f0 02 b8 b.w #4 <__ThumbV7PILongThunk_elsewhere>
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// CHECK-NEXT: 1004: 00 f0 06 b8 b.w #12 <__ThumbV7PILongThunk_weakref>
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// CHECK: __ThumbV7PILongThunk_elsewhere:
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// CHECK-NEXT: 1008: 40 f2 2c 0c movw r12, #44
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// CHECK-NEXT: 100c: c0 f2 00 0c movt r12, #0
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// CHECK-NEXT: 1010: fc 44 add r12, pc
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// CHECK-NEXT: 1012: 60 47 bx r12
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// CHECK: __ThumbV7PILongThunk_weakref:
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// CHECK-NEXT: 1014: 40 f2 30 0c movw r12, #48
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// CHECK-NEXT: 1018: c0 f2 00 0c movt r12, #0
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// CHECK-NEXT: 101c: fc 44 add r12, pc
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// CHECK-NEXT: 101e: 60 47 bx r12
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// PLT: Disassembly of section .plt:
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// PLT-NEXT: $a:
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// PLT-NEXT: 1020: 04 e0 2d e5 str lr, [sp, #-4]!
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// PLT-NEXT: 1024: 00 e6 8f e2 add lr, pc, #0, #12
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// PLT-NEXT: 1028: 00 ea 8e e2 add lr, lr, #0, #20
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// PLT-NEXT: 102c: dc ff be e5 ldr pc, [lr, #4060]!
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// PLT: $d:
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// PLT-NEXT: 1030: d4 d4 d4 d4 .word 0xd4d4d4d4
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// PLT-NEXT: 1034: d4 d4 d4 d4 .word 0xd4d4d4d4
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// PLT-NEXT: 1038: d4 d4 d4 d4 .word 0xd4d4d4d4
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// PLT-NEXT: 103c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// PLT: $a:
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// PLT-NEXT: 1040: 00 c6 8f e2 add r12, pc, #0, #12
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// PLT-NEXT: 1044: 00 ca 8c e2 add r12, r12, #0, #20
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// PLT-NEXT: 1048: c4 ff bc e5 ldr pc, [r12, #4036]!
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// PLT: $d:
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// PLT-NEXT: 104c: d4 d4 d4 d4 .word 0xd4d4d4d4
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// PLT: $a:
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// PLT-NEXT: 1050: 00 c6 8f e2 add r12, pc, #0, #12
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// PLT-NEXT: 1054: 00 ca 8c e2 add r12, r12, #0, #20
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// PLT-NEXT: 1058: b8 ff bc e5 ldr pc, [r12, #4024]!
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// PLT: $d:
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// PLT-NEXT: 105c: d4 d4 d4 d4 .word 0xd4d4d4d4
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