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[ARM] Create relocations for Thumb functions calling ARM fns in ELF.

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Summary:
Without using a fixup in this case, BL will be used instead of BLX to
call internal ARM functions from Thumb functions.

Reviewers: rafael, t.p.northover, peter.smith, kristof.beyls

Reviewed By: peter.smith

Subscribers: srhines, echristo, aemerson, rengolin, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D33436

llvm-svn: 304413
This commit is contained in:
Florian Hahn 2017-06-01 13:50:57 +00:00
parent d2f50a9b16
commit 22da9fa5d1
3 changed files with 87 additions and 0 deletions
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9
lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
View File

@ -729,6 +729,15 @@ void ARMAsmBackend::processFixupValue(const MCAssembler &Asm,
// linker can handle it. GNU AS produces an error in this case.
if (Sym->isExternal() || Value >= 0x400004)
IsResolved = false;
// When an ARM function is called from a Thumb function, produce a
// relocation so the linker will use the correct branch instruction for ELF
// binaries.
if (Sym->isELF()) {
unsigned Type = dyn_cast<MCSymbolELF>(Sym)->getType();
if ((Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC) &&
!Asm.isThumbFunc(Sym))
IsResolved = false;
}
}
// We must always generate a relocation for BL/BLX instructions if we have
// a symbol to reference, as the linker relies on knowing the destination

1
test/MC/ARM/big-endian-thumb-fixup.s
View File

@ -4,6 +4,7 @@
.text
.align 2
.code 16
.thumb_func
@ARM::fixup_arm_thumb_bl
.section s_thumb_bl,"ax",%progbits

77
test/MC/ARM/mixed-arm-thumb-bl-fixup.ll Normal file
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@ -0,0 +1,77 @@
; RUN: llc -O0 < %s -mtriple armv7-linux-gnueabi -o - \
; RUN: | llvm-mc -triple armv7-linux-gnueabi -filetype=obj -o - \
; RUN: | llvm-readobj -r | FileCheck --check-prefix LINUX %s
; RUN: llc -O0 < %s -mtriple armv7-linux-android -o - \
; RUN: | llvm-mc -triple armv7-linux-android -filetype=obj -o - \
; RUN: | llvm-readobj -r | FileCheck --check-prefix LINUX %s
; RUN: llc -O0 < %s -mtriple armv7-apple-ios -o - \
; RUN: | llvm-mc -triple armv7-apple-ios -filetype=obj -o - \
; RUN: | llvm-readobj -r | FileCheck --check-prefix IOS %s
define void @thumb_caller() #0 {
call void @internal_arm_fn()
call void @global_arm_fn()
call void @internal_thumb_fn()
call void @global_thumb_fn()
ret void
}
define void @arm_caller() #1 {
call void @internal_arm_fn()
call void @global_arm_fn()
call void @internal_thumb_fn()
call void @global_thumb_fn()
ret void
}
define internal void @internal_thumb_fn() #0 {
ret void
}
define void @global_thumb_fn() #0 {
entry:
br label %end
end:
br label %end
ret void
}
define internal void @internal_arm_fn() #1 {
ret void
}
define void @global_arm_fn() #1 {
entry:
br label %end
end:
br label %end
ret void
}
attributes #0 = { "target-features"="+thumb-mode" }
attributes #1 = { "target-features"="-thumb-mode" }
; LINUX: Section (3) .rel.text {
; LINUX-NEXT: 0x2 R_ARM_THM_CALL internal_arm_fn 0x0
; LINUX-NEXT: 0x6 R_ARM_THM_CALL global_arm_fn 0x0
; LINUX-NEXT: 0xE R_ARM_THM_CALL global_thumb_fn 0x0
; LINUX-NEXT: 0x1C R_ARM_CALL internal_arm_fn 0x0
; LINUX-NEXT: 0x20 R_ARM_CALL global_arm_fn 0x0
; LINUX-NEXT: 0x24 R_ARM_CALL internal_thumb_fn 0x0
; LINUX-NEXT: 0x28 R_ARM_CALL global_thumb_fn 0x0
; LINUX-NEXT: }
; IOS: Section __text {
; IOS-NEXT: 0x2C 1 2 0 ARM_RELOC_BR24 0 __text
; IOS-NEXT: 0x28 1 2 0 ARM_RELOC_BR24 0 __text
; IOS-NEXT: 0x24 1 2 0 ARM_RELOC_BR24 0 __text
; IOS-NEXT: 0x20 1 2 0 ARM_RELOC_BR24 0 __text
; IOS-NEXT: 0x10 1 2 0 ARM_THUMB_RELOC_BR22 0 __text
; IOS-NEXT: 0xC 1 2 0 ARM_THUMB_RELOC_BR22 0 __text
; IOS-NEXT: 0x8 1 2 0 ARM_THUMB_RELOC_BR22 0 __text
; IOS-NEXT: 0x4 1 2 0 ARM_THUMB_RELOC_BR22 0 __text
; IOS-NEXT: }