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[ARM] Restore the right frame pointer register in Int_eh_sjlj_longjmp 

In setupEntryBlockAndCallSites in CodeGen/SjLjEHPrepare.cpp,
we fetch and store the actual frame pointer, but on return via
the longjmp intrinsic, it always was restored into the r7 variable.

On windows, the frame pointer should be restored into r11 instead of r7.

On Darwin (where sjlj exception handling is used by default), the frame
pointer is always r7, both in arm and thumb mode, and likewise, on
windows, the frame pointer always is r11.

On linux however, if sjlj exception handling is enabled (which it isn't
by default), libcxxabi and the user code can be built in differing modes
using different registers as frame pointer. Therefore, when restoring
registers on a platform where we don't always use the same register
depending on code mode, restore both r7 and r11.

Differential Revision: https://reviews.llvm.org/D38253

llvm-svn: 314451
This commit is contained in:
Martin Storsjo 2017-09-28 19:04:30 +00:00
parent adceba59a2
commit d6218cc385
2 changed files with 70 additions and 14 deletions
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72
llvm/lib/Target/ARM/ARMAsmPrinter.cpp
View File

@ -1204,6 +1204,10 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
MCTargetStreamer &TS = *OutStreamer->getTargetStreamer();
ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
const MachineFunction &MF = *MI->getParent()->getParent();
const ARMSubtarget &STI = MF.getSubtarget<ARMSubtarget>();
unsigned FramePtr = STI.useR7AsFramePointer() ? ARM::R7 : ARM::R11;
// If we just ended a constant pool, mark it as such.
if (InConstantPool && MI->getOpcode() != ARM::CONSTPOOL_ENTRY) {
OutStreamer->EmitDataRegion(MCDR_DataRegionEnd);
@ -1884,13 +1888,33 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
.addImm(ARMCC::AL)
.addReg(0));
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::LDRi12)
.addReg(ARM::R7)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
if (STI.isTargetDarwin() || STI.isTargetWindows()) {
// These platforms always use the same frame register
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::LDRi12)
.addReg(FramePtr)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
} else {
// If the calling code might use either R7 or R11 as
// frame pointer register, restore it into both.
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::LDRi12)
.addReg(ARM::R7)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::LDRi12)
.addReg(ARM::R11)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
}
assert(Subtarget->hasV4TOps());
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::BX)
@ -1934,13 +1958,33 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
.addImm(ARMCC::AL)
.addReg(0));
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::tLDRi)
.addReg(ARM::R7)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
if (STI.isTargetDarwin() || STI.isTargetWindows()) {
// These platforms always use the same frame register
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::tLDRi)
.addReg(FramePtr)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
} else {
// If the calling code might use either R7 or R11 as
// frame pointer register, restore it into both.
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::tLDRi)
.addReg(ARM::R7)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::tLDRi)
.addReg(ARM::R11)
.addReg(SrcReg)
.addImm(0)
// Predicate.
.addImm(ARMCC::AL)
.addReg(0));
}
EmitToStreamer(*OutStreamer, MCInstBuilder(ARM::tBX)
.addReg(ScratchReg)

12
llvm/test/CodeGen/ARM/setjmp_longjmp.ll
View File

@ -1,4 +1,6 @@
; RUN: llc %s -o - | FileCheck %s
; RUN: llc -mtriple=armv7-linux -exception-model sjlj %s -o - | FileCheck %s -check-prefix CHECK-LINUX
; RUN: llc -mtriple=thumbv7-win32 -exception-model sjlj %s -o - | FileCheck %s -check-prefix CHECK-WIN32
target triple = "armv7-apple-ios"
declare i32 @llvm.eh.sjlj.setjmp(i8*)
@ -28,6 +30,16 @@ declare i8* @llvm.stacksave()
; CHECK-NEXT: ldr [[DESTREG:r[0-9]+]], {{\[}}[[BUFREG]], #4]
; CHECK-NEXT: ldr r7, {{\[}}[[BUFREG]]{{\]}}
; CHECK-NEXT: bx [[DESTREG]]
; CHECK-LINUX: ldr sp, [{{\s*}}[[BUFREG:r[0-9]+]], #8]
; CHECK-LINUX-NEXT: ldr [[DESTREG:r[0-9]+]], {{\[}}[[BUFREG]], #4]
; CHECK-LINUX-NEXT: ldr r7, {{\[}}[[BUFREG]]{{\]}}
; CHECK-LINUX-NEXT: ldr r11, {{\[}}[[BUFREG]]{{\]}}
; CHECK-LINUX-NEXT: bx [[DESTREG]]
; CHECK-WIN32: ldr.w r11, [{{\s*}}[[BUFREG:r[0-9]+]]]
; CHECK-WIN32-NEXT: ldr.w sp, {{\[}}[[BUFREG]], #8]
; CHECK-WIN32-NEXT: ldr.w pc, {{\[}}[[BUFREG]], #4]
define void @foobar() {
entry:
%buf = alloca [5 x i8*], align 4