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[Linker] Add directives to support mixing ARM/Thumb module-level inline asm.

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Summary:
By prepending `.text .thumb .balign 2` to the module-level inline
assembly from a Thumb module, the assembler will generate the assembly
from that module as Thumb, even if the destination module uses an ARM
triple. Similar directives are used for module-level inline assembly in
ARM modules.

The alignment and instruction set are reset based on the target triple
before emitting the first function label.

Reviewers: olista01, tejohnson, echristo, t.p.northover, rafael

Reviewed By: echristo

Subscribers: aemerson, javed.absar, eraman, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D34622

llvm-svn: 307772
This commit is contained in:
Florian Hahn 2017-07-12 11:52:28 +00:00
parent f5b245992e
commit f4278d3016
3 changed files with 39 additions and 2 deletions
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18
lib/Linker/IRMover.cpp
View File

@ -1256,6 +1256,18 @@ Error IRLinker::linkModuleFlagsMetadata() {
return Error::success();
}
/// Return InlineAsm adjusted with target-specific directives if required.
/// For ARM and Thumb, we have to add directives to select the appropriate ISA
/// to support mixing module-level inline assembly from ARM and Thumb modules.
static std::string adjustInlineAsm(const std::string &InlineAsm,
const Triple &Triple) {
if (Triple.getArch() == Triple::thumb || Triple.getArch() == Triple::thumbeb)
return ".text\n.balign 2\n.thumb\n" + InlineAsm;
if (Triple.getArch() == Triple::arm || Triple.getArch() == Triple::armeb)
return ".text\n.balign 4\n.arm\n" + InlineAsm;
return InlineAsm;
}
Error IRLinker::run() {
// Ensure metadata materialized before value mapping.
if (SrcM->getMaterializer())
@ -1293,11 +1305,13 @@ Error IRLinker::run() {
// Append the module inline asm string.
if (!IsPerformingImport && !SrcM->getModuleInlineAsm().empty()) {
std::string SrcModuleInlineAsm = adjustInlineAsm(SrcM->getModuleInlineAsm(),
SrcTriple);
if (DstM.getModuleInlineAsm().empty())
DstM.setModuleInlineAsm(SrcM->getModuleInlineAsm());
DstM.setModuleInlineAsm(SrcModuleInlineAsm);
else
DstM.setModuleInlineAsm(DstM.getModuleInlineAsm() + "\n" +
SrcM->getModuleInlineAsm());
SrcModuleInlineAsm);
}
// Loop over all of the linked values to compute type mappings.

3
test/Linker/Inputs/thumb-module-inline-asm.ll Normal file
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@ -0,0 +1,3 @@
target triple = "thumbv7-linux-gnueabihf"
module asm "orn r1, r2, r2"

20
test/Linker/link-arm-and-thumb-module-inline-asm.ll Normal file
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@ -0,0 +1,20 @@
; This test checks that proper directives to switch between ARM and Thumb mode
; are added when linking ARM and Thumb modules.
; RUN: llvm-as %s -o %t1.bc
; RUN: llvm-as %p/Inputs/thumb-module-inline-asm.ll -o %t2.bc
; RUN: llvm-link %t1.bc %t2.bc -S 2> %t3.out | FileCheck %s
target triple = "armv7-linux-gnueabihf"
module asm "add r1, r2, r2"
; CHECK: .text
; CHECK-NEXT: .balign 4
; CHECK-NEXT: .arm
; CHECK-NEXT: add r1, r2, r2
; CHECK-NEXT: module asm
; CHECK-NEXT: .text
; CHECK-NEXT: .balign 2
; CHECK-NEXT: .thumb
; CHECK-NEXT: orn r1, r2, r2