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[llvm][MC][ARM][Assembly] Emit relocations for ADRs and big-endian targets #73834

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Merged
merged 2 commits into from
Dec 1, 2023
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[llvm][MC][ARM][Assembly] Emit relocations for ADRs and big-endian targets #73834

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d044349
[llvm][MC][ARM][Assembly] Emit relocations for ADRs and big-endian ta…
eleanor-arm Nov 29, 2023
eed3aa3
fixup! [llvm][MC][ARM][Assembly] Emit relocations for ADRs and big-en…
eleanor-arm Dec 1, 2023
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15 changes: 9 additions & 6 deletions llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -88,10 +88,12 @@ const MCFixupKindInfo &ARMAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
IsPCRelConstant | MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_arm_ldst_abs_12", 0, 32, 0},
{"fixup_thumb_adr_pcrel_10", 0, 8,
IsPCRelConstant | MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_arm_adr_pcrel_12", 0, 32, IsPCRelConstant},
MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_arm_adr_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_t2_adr_pcrel_12", 0, 32,
IsPCRelConstant | MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_arm_condbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_arm_uncondbranch", 0, 24, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_t2_condbranch", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
Expand Down Expand Up @@ -133,10 +135,11 @@ const MCFixupKindInfo &ARMAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
// ARMFixupKinds.h.
//
// Name Offset (bits) Size (bits) Flags
{"fixup_arm_ldst_pcrel_12", 0, 32, IsPCRelConstant},
{"fixup_arm_ldst_pcrel_12", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_t2_ldst_pcrel_12", 0, 32,
IsPCRelConstant | MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_arm_pcrel_10_unscaled", 0, 32, IsPCRelConstant},
MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_arm_pcrel_10_unscaled", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_arm_pcrel_10", 0, 32, IsPCRelConstant},
{"fixup_t2_pcrel_10", 0, 32,
MCFixupKindInfo::FKF_IsPCRel |
Expand Down
6 changes: 6 additions & 0 deletions llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -164,6 +164,12 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
return ELF::R_ARM_LDRS_PC_G0;
case ARM::fixup_t2_ldst_pcrel_12:
return ELF::R_ARM_THM_PC12;
case ARM::fixup_arm_adr_pcrel_12:
return ELF::R_ARM_ALU_PC_G0;
case ARM::fixup_thumb_adr_pcrel_10:
return ELF::R_ARM_THM_PC8;
case ARM::fixup_t2_adr_pcrel_12:
return ELF::R_ARM_THM_ALU_PREL_11_0;
case ARM::fixup_bf_target:
return ELF::R_ARM_THM_BF16;
case ARM::fixup_bfc_target:
Expand Down
26 changes: 26 additions & 0 deletions llvm/test/MC/ARM/pcrel-adr16-relocs.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
@ RUN: llvm-mc -filetype=obj --triple=thumbv6m-none-eabi %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=RELOC
@ RUN: llvm-objdump -d --triple=thumbv6m-none-eabi %t | FileCheck %s --check-prefix=ADDEND

.section .text._func1, "ax"

.balign 4
.global _func1
.type _func1, %function
_func1:
adr r0, _func2
@ RELOC: R_ARM_THM_PC8
bx lr

// Checking the encoding only, as the disassembly is not quite correct here.
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"here, it should be..."

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Also open an issue for the problem itself?

//00000000 <_func1>:
// 0: a0ff adr r0, #1020 <_func1+0x103>

// Thumb16 encoding supports only adding of the encoded immediate (not
// subtracting, see [Arm ARM]), therefore sign change is required if the pcrel
// offset is negative. This makes the calculation of the addend for
// R_ARM_THM_PC8 more complex, for details see [ELF for the Arm 32-bit
// architecture].

@ ADDEND: a0ff adr

24 changes: 24 additions & 0 deletions llvm/test/MC/ARM/pcrel-adr32-relocs.s
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@@ -0,0 +1,24 @@
@ RUN: llvm-mc -filetype=obj -triple=armv7 %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=RELOC
@ RUN: llvm-objdump -d --triple=armv7 %t | FileCheck %s --check-prefix=ADDEND

@ RUN: llvm-mc -filetype=obj --triple=armebv7-unknown-unknown %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=RELOC
@ RUN: llvm-objdump -d --triple=armebv7-unknown-unknown %t | FileCheck %s --check-prefix=ADDEND

.section .text._func1, "ax"

.balign 4
.global _func1
.type _func1, %function
_func1:
adr r0, _func2
@ RELOC: R_ARM_ALU_PC_G0
.thumb
adr r0, _func2
@ RELOC: R_ARM_THM_ALU_PREL_11_0
bx lr

@ ADDEND: sub r0, pc, #8
@ ADDEND-NEXT: adr.w r0, #-4

6 changes: 6 additions & 0 deletions llvm/test/MC/ARM/pcrel-arm-ldr-imm8-relocs.s
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Original file line number Diff line number Diff line change
@@ -1,13 +1,17 @@
@ RUN: llvm-mc -filetype=obj -triple=armv7 %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=ARM
@ RUN: llvm-objdump -d --triple=armv7 %t | FileCheck %s --check-prefix=ARM_ADDEND
@ RUN: llvm-mc -filetype=obj --triple=armebv7-unknown-unknown %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=ARM
@ RUN: llvm-objdump -d --triple=armebv7-unknown-unknown %t | FileCheck %s --check-prefix=ARM_ADDEND

@ ARM: R_ARM_LDRS_PC_G0
@ ARM: R_ARM_LDRS_PC_G0
@ ARM: R_ARM_LDRS_PC_G0
@ ARM: R_ARM_LDRS_PC_G0
@ ARM: R_ARM_LDRS_PC_G0
@ ARM: R_ARM_LDRS_PC_G0
@ ARM: R_ARM_LDRS_PC_G0

// The value format is decimal in these specific cases, but it's hex for other
// ldr instructions. These checks are valid for both formats.
Expand All @@ -18,6 +22,7 @@
@ ARM_ADDEND: r0, [pc, #-{{16|0x10}}]
@ ARM_ADDEND: r0, [pc, #-{{16|0x10}}]
@ ARM_ADDEND: r0, [pc]
@ ARM_ADDEND: r0, r1, [pc]

.arm
.section .text.bar, "ax"
Expand All @@ -31,6 +36,7 @@ bar:
ldrh r0, just_after-8
ldrsb r0, just_after-8
ldrsh r0, foo+8
ldrd r0,r1, foo+8
bx lr

.section .data.foo, "a", %progbits
Expand Down
10 changes: 2 additions & 8 deletions llvm/test/MC/ARM/pcrel-global.s
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Original file line number Diff line number Diff line change
Expand Up @@ -7,11 +7,9 @@
@ CHECK: There are no relocations in this file.

@ DISASM-LABEL: <bar>:
@ DISASM-NEXT: adr.w r0, #-4
@ DISASM-NEXT: adr.w r0, #-8
@ DISASM-NEXT: ldr r0, [pc, #0x0] @ 0x14 <bar+0xc>
@ DISASM-NEXT: ldr r0, [pc, #0x0] @ 0x8 <bar+0x4>
@ DISASM-NEXT: add r0, pc
@ DISASM-NEXT: .word 0xfffffff3
@ DISASM-NEXT: .word 0xfffffffb
@@ GNU assembler creates an R_ARM_REL32 referencing bar.
@ DISASM-NOT: {{.}}

Expand All @@ -20,16 +18,12 @@
.globl foo
foo:
vldr d0, foo @ arm_pcrel_10
adr r2, foo @ arm_adr_pcrel_12

.thumb
.thumb_func
.type bar, %function
.globl bar
bar:
adr r0, bar @ thumb_adr_pcrel_10
adr.w r0, bar @ t2_adr_pcrel_12

ldr r0, .LCPI
.LPC0_1:
add r0, pc
Expand Down
8 changes: 6 additions & 2 deletions llvm/test/MC/ARM/pcrel-ldr-relocs.s
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,17 @@
@ RUN: llvm-mc -filetype=obj -triple=thumbv7 %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=THUMB
@ RUN: llvm-objdump -d --triple=thumbv7 %t | FileCheck %s --check-prefix=THUMB_ADDEND
@ RUN: llvm-mc -filetype=obj -triple=armebv7 %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=ARM
@ RUN: llvm-objdump -d --triple=armebv7 %t | FileCheck %s --check-prefix=ARM_ADDEND
@ RUN: llvm-mc -filetype=obj -triple=thumbebv7 %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=THUMB
@ RUN: llvm-objdump -d --triple=thumbebv7 %t | FileCheck %s --check-prefix=THUMB_ADDEND

@ ARM: R_ARM_LDR_PC_G0
@ ARM: R_ARM_LDR_PC_G0
@ ARM: R_ARM_LDR_PC_G0
@ ARM: R_ARM_LDR_PC_G0

@ ARM_ADDEND: r0, [pc, #-0x8]
@ ARM_ADDEND: r0, [pc, #-0x8]
@ ARM_ADDEND: r0, [pc, #-0x10]
Expand All @@ -19,7 +24,6 @@
@ THUMB: R_ARM_THM_PC12
@ THUMB: R_ARM_THM_PC12
@ THUMB: R_ARM_THM_PC12

@ THUMB_ADDEND: r0, [pc, #-0x4]
@ THUMB_ADDEND: r0, [pc, #-0x4]
@ THUMB_ADDEND: r0, [pc, #-0xc]
Expand Down
3 changes: 3 additions & 0 deletions llvm/test/MC/ARM/pcrel-thumb-ldr2-relocs.s
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Original file line number Diff line number Diff line change
@@ -1,6 +1,9 @@
@ RUN: llvm-mc -filetype=obj -triple=thumbv7 %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=THUMB
@ RUN: llvm-objdump -d --triple=thumbv7 %t | FileCheck %s --check-prefix=THUMB_ADDEND
@ RUN: llvm-mc -filetype=obj --triple=thumbebv7-unknown-unknown %s -o %t
@ RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=THUMB
@ RUN: llvm-objdump -d --triple=thumbebv7-unknown-unknown %t | FileCheck %s --check-prefix=THUMB_ADDEND

@ All the ldr variants produce a relocation
@ THUMB: R_ARM_THM_PC12
Expand Down
1 change: 0 additions & 1 deletion llvm/test/MC/ARM/thumb1-relax-adr.s
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
@ RUN: not llvm-mc -triple thumbv6m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
@ RUN: not llvm-mc -triple thumbv7m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
@ RUN: not llvm-mc -triple thumbv7m-none-eabi -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s

.global func1
_func1:
Expand Down