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[ARM] Create relocations for unconditional branches.

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Summary:
Relocations are required for unconditional branches to function symbols with
different execution mode. Without this patch, incorrect branches are
generated for tail calls between functions with different execution
mode.


Reviewers: peter.smith, rafael, echristo, kristof.beyls

Reviewed By: peter.smith

Subscribers: aemerson, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D33898

llvm-svn: 304882
This commit is contained in:
Florian Hahn 2017-06-07 08:54:47 +00:00
parent c9de72eff5
commit 9868c996a4
2 changed files with 37 additions and 7 deletions
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19
lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
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@ -748,13 +748,18 @@ 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))
}
// Create relocations for unconditional branches to function symbols with
// different execution mode in ELF binaries.
if (Sym && Sym->isELF()) {
unsigned Type = dyn_cast<MCSymbolELF>(Sym)->getType();
if ((Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)) {
unsigned FixupKind = Fixup.getKind() ;
if (Asm.isThumbFunc(Sym) && (FixupKind == ARM::fixup_arm_uncondbranch))
IsResolved = false;
if (!Asm.isThumbFunc(Sym) && (FixupKind == ARM::fixup_arm_thumb_br ||
FixupKind == ARM::fixup_arm_thumb_bl ||
FixupKind == ARM::fixup_t2_uncondbranch))
IsResolved = false;
}
}

25
test/MC/ARM/arm-thumb-tail-call.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: llc -O0 < %s -mtriple armv7-linux-gnueabi -o - \
; RUN: | llvm-mc -triple armv7-linux-gnueabi -filetype=obj -o - \
; RUN: | llvm-readobj -r | FileCheck %s
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv7--linux-gnueabihf"
define internal i32 @arm_fn() #1 {
%1 = tail call i32 @thumb_fn()
ret i32 %1
}
define internal i32 @thumb_fn() #2 {
%1 = tail call i32 @arm_fn()
ret i32 %1
}
attributes #1 = { "target-features"="-thumb-mode" }
attributes #2 = { "target-features"="+thumb-mode" }
; CHECK: Relocations [
; CHECK-NEXT: Section (3) .rel.text {
; CHECK-NEXT: 0x0 R_ARM_JUMP24 thumb_fn 0x0
; CHECK-NEXT: 0x4 R_ARM_THM_JUMP24 arm_fn 0x0
; CHECK-NEXT: }