[llvm] r306927 - Rewrite ARM execute only support to avoid the use of a command line flag and unqualified ARMSubtarget lookup.
Luke Cheeseman via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 14 07:57:01 PDT 2017
Hi Eric,
You recently commited:
[llvm] r306927 - Rewrite ARM execute only support to avoid the use of a command line flag and unqualified ARMSubtarget lookup.
This is breaking some of our testing as it changes the attributes of the default .text section, namely the section is no longer execute only. This causes two .text sections to be created (one that is execute only and one that is not); some tools may have issues with this. For example, a linker may merge the two .text sections into one segment and remove the PURECODE flag in conformance with section 4.3.3 of http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044f/IHI0044F_aaelf.pdf .
Furthermore, in your patch you made similar changes that were initially proposed by Prakhar (namely implementing execute only as a feature flag) but were discussed and decided against. See https://reviews.llvm.org/D27449?id=80748#inline-237468 .
Take the following example (part of the regression test suite):
$ cat test/CodeGen/ARM/execute-only-section.ll
...
; CHECK: .section .text,"axy",%progbits,unique,0
; CHECK-NOT: .section
; CHECK-NOT: .text
; CHECK: .globl test_SectionForGlobal
; CHECK: .type test_SectionForGlobal,%function
define void @test_SectionForGlobal() {
entry:
ret void
}
...
$ llc test/CodeGen/ARM/execute-only-section.ll -mtriple=thumbv7m -mattr=+execute-only -o -
.text
.syntax unified
.eabi_attribute
67, "2.09" @ Tag_conformance
....
"test/CodeGen/ARM/execute-only-section.ll"
.section
.text,"axy",%progbits,unique,0
.globl
test_SectionForGlobal @ -- Begin function test_SectionForGlobal
.p2align
2
.type
test_SectionForGlobal,%function
.code
16 @ @test_SectionForGlobal
.thumb_func
test_SectionForGlobal:
.fnstart
@ BB#0: @ %entry
...
There are now two .text sections, one which is execute only and one which is not. This test still passes however as file check finds the execute only .text section.
This is due to this part of the commit:
--- llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp Fri Jun 30 19:55:22 2017
@@ -32,7 +32,7 @@ void ARMElfTargetObjectFile::Initialize(
const TargetMachine &TM) {
const ARMBaseTargetMachine &ARM_TM = static_cast<const ARMBaseTargetMachine &>(TM);
bool isAAPCS_ABI = ARM_TM.TargetABI == ARMBaseTargetMachine::ARMABI::ARM_ABI_AAPCS;
- genExecuteOnly = ARM_TM.getSubtargetImpl()->genExecuteOnly();
+ // genExecuteOnly = ARM_TM.getSubtargetImpl()->genExecuteOnly();
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
InitializeELF(isAAPCS_ABI);
@@ -43,16 +43,6 @@ void ARMElfTargetObjectFile::Initialize(
AttributesSection =
getContext().getELFSection(".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
-
- // Make code section unreadable when in execute-only mode
- if (genExecuteOnly) {
- unsigned Type = ELF::SHT_PROGBITS;
- unsigned Flags = ELF::SHF_EXECINSTR | ELF::SHF_ALLOC | ELF::SHF_ARM_PURECODE;
- // Since we cannot modify flags for an existing section, we create a new
- // section with the right flags, and use 0 as the unique ID for
- // execute-only text
- TextSection = Ctx.getELFSection(".text", Type, Flags, 0, "", 0U);
- }
}
Kind Regards,
Luke
________________________________
From: llvm-commits <llvm-commits-bounces at lists.llvm.org> on behalf of Eric Christopher via llvm-commits <llvm-commits at lists.llvm.org>
Sent: 01 July 2017 03:55:22
To: llvm-commits at lists.llvm.org
Subject: [llvm] r306927 - Rewrite ARM execute only support to avoid the use of a command line flag and unqualified ARMSubtarget lookup.
Author: echristo
Date: Fri Jun 30 19:55:22 2017
New Revision: 306927
URL: http://llvm.org/viewvc/llvm-project?rev=306927&view=rev
Log:
Rewrite ARM execute only support to avoid the use of a command line flag and unqualified ARMSubtarget lookup.
Paired with a clang commit to use the new behavior.
Modified:
llvm/trunk/lib/Target/ARM/ARM.td
llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp
llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp
llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.h
llvm/trunk/test/CodeGen/ARM/constantfp.ll
llvm/trunk/test/CodeGen/ARM/execute-only-big-stack-frame.ll
llvm/trunk/test/CodeGen/ARM/execute-only-section.ll
llvm/trunk/test/CodeGen/ARM/execute-only.ll
Modified: llvm/trunk/lib/Target/ARM/ARM.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARM.td?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARM.td (original)
+++ llvm/trunk/lib/Target/ARM/ARM.td Fri Jun 30 19:55:22 2017
@@ -269,6 +269,10 @@ def FeatureLongCalls : SubtargetFeature<
"Generate calls via indirect call "
"instructions">;
+def FeatureExecuteOnly
+ : SubtargetFeature<"execute-only", "GenExecuteOnly", "true",
+ "Enable the generation of execute only code.">;
+
def FeatureReserveR9 : SubtargetFeature<"reserve-r9", "ReserveR9", "true",
"Reserve R9, making it unavailable as "
"GPR">;
Modified: llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp Fri Jun 30 19:55:22 2017
@@ -92,11 +92,6 @@ ARMSubtarget &ARMSubtarget::initializeSu
return *this;
}
-/// EnableExecuteOnly - Enables the generation of execute-only code on supported
-/// targets
-static cl::opt<bool>
-EnableExecuteOnly("arm-execute-only");
-
ARMFrameLowering *ARMSubtarget::initializeFrameLowering(StringRef CPU,
StringRef FS) {
ARMSubtarget &STI = initializeSubtargetDependencies(CPU, FS);
@@ -139,9 +134,8 @@ ARMSubtarget::ARMSubtarget(const Triple
const std::string &FS,
const ARMBaseTargetMachine &TM, bool IsLittle)
: ARMGenSubtargetInfo(TT, CPU, FS), UseMulOps(UseFusedMulOps),
- GenExecuteOnly(EnableExecuteOnly), CPUString(CPU), IsLittle(IsLittle),
- TargetTriple(TT), Options(TM.Options), TM(TM),
- FrameLowering(initializeFrameLowering(CPU, FS)),
+ CPUString(CPU), IsLittle(IsLittle), TargetTriple(TT), Options(TM.Options),
+ TM(TM), FrameLowering(initializeFrameLowering(CPU, FS)),
// At this point initializeSubtargetDependencies has been called so
// we can query directly.
InstrInfo(isThumb1Only()
Modified: llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.cpp Fri Jun 30 19:55:22 2017
@@ -32,7 +32,7 @@ void ARMElfTargetObjectFile::Initialize(
const TargetMachine &TM) {
const ARMBaseTargetMachine &ARM_TM = static_cast<const ARMBaseTargetMachine &>(TM);
bool isAAPCS_ABI = ARM_TM.TargetABI == ARMBaseTargetMachine::ARMABI::ARM_ABI_AAPCS;
- genExecuteOnly = ARM_TM.getSubtargetImpl()->genExecuteOnly();
+ // genExecuteOnly = ARM_TM.getSubtargetImpl()->genExecuteOnly();
TargetLoweringObjectFileELF::Initialize(Ctx, TM);
InitializeELF(isAAPCS_ABI);
@@ -43,16 +43,6 @@ void ARMElfTargetObjectFile::Initialize(
AttributesSection =
getContext().getELFSection(".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
-
- // Make code section unreadable when in execute-only mode
- if (genExecuteOnly) {
- unsigned Type = ELF::SHT_PROGBITS;
- unsigned Flags = ELF::SHF_EXECINSTR | ELF::SHF_ALLOC | ELF::SHF_ARM_PURECODE;
- // Since we cannot modify flags for an existing section, we create a new
- // section with the right flags, and use 0 as the unique ID for
- // execute-only text
- TextSection = Ctx.getELFSection(".text", Type, Flags, 0, "", 0U);
- }
}
const MCExpr *ARMElfTargetObjectFile::getTTypeGlobalReference(
@@ -74,21 +64,27 @@ getDebugThreadLocalSymbol(const MCSymbol
getContext());
}
-MCSection *
-ARMElfTargetObjectFile::getExplicitSectionGlobal(const GlobalObject *GO,
- SectionKind SK, const TargetMachine &TM) const {
+static bool isExecuteOnlyFunction(const GlobalObject *GO, SectionKind SK,
+ const TargetMachine &TM) {
+ if (const Function *F = dyn_cast<Function>(GO))
+ if (TM.getSubtarget<ARMSubtarget>(*F).genExecuteOnly() && SK.isText())
+ return true;
+ return false;
+}
+
+MCSection *ARMElfTargetObjectFile::getExplicitSectionGlobal(
+ const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {
// Set execute-only access for the explicit section
- if (genExecuteOnly && SK.isText())
+ if (isExecuteOnlyFunction(GO, SK, TM))
SK = SectionKind::getExecuteOnly();
return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, SK, TM);
}
-MCSection *
-ARMElfTargetObjectFile::SelectSectionForGlobal(const GlobalObject *GO,
- SectionKind SK, const TargetMachine &TM) const {
+MCSection *ARMElfTargetObjectFile::SelectSectionForGlobal(
+ const GlobalObject *GO, SectionKind SK, const TargetMachine &TM) const {
// Place the global in the execute-only text section
- if (genExecuteOnly && SK.isText())
+ if (isExecuteOnlyFunction(GO, SK, TM))
SK = SectionKind::getExecuteOnly();
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, SK, TM);
Modified: llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.h?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMTargetObjectFile.h Fri Jun 30 19:55:22 2017
@@ -16,8 +16,6 @@
namespace llvm {
class ARMElfTargetObjectFile : public TargetLoweringObjectFileELF {
- mutable bool genExecuteOnly = false;
-
protected:
const MCSection *AttributesSection = nullptr;
Modified: llvm/trunk/test/CodeGen/ARM/constantfp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/constantfp.ll?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/constantfp.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/constantfp.ll Fri Jun 30 19:55:22 2017
@@ -5,25 +5,25 @@
; RUN: llc -mtriple=thumbv7m -mcpu=cortex-m4 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-NO-XO %s
-; RUN: llc -mtriple=thumbv7m -arm-execute-only -mcpu=cortex-m4 %s -o - \
+; RUN: llc -mtriple=thumbv7m -mattr=+execute-only -mcpu=cortex-m4 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE %s
-; RUN: llc -mtriple=thumbv7meb -arm-execute-only -mcpu=cortex-m4 %s -o - \
+; RUN: llc -mtriple=thumbv7meb -mattr=+execute-only -mcpu=cortex-m4 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE-BE %s
-; RUN: llc -mtriple=thumbv7m -arm-execute-only -mcpu=cortex-m4 -relocation-model=ropi %s -o - \
+; RUN: llc -mtriple=thumbv7m -mattr=+execute-only -mcpu=cortex-m4 -relocation-model=ropi %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-XO-ROPI %s
; RUN: llc -mtriple=thumbv8m.main -mattr=fp-armv8 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-NO-XO %s
-; RUN: llc -mtriple=thumbv8m.main -arm-execute-only -mattr=fp-armv8 %s -o - \
+; RUN: llc -mtriple=thumbv8m.main -mattr=+execute-only -mattr=fp-armv8 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE %s
-; RUN: llc -mtriple=thumbv8m.maineb -arm-execute-only -mattr=fp-armv8 %s -o - \
+; RUN: llc -mtriple=thumbv8m.maineb -mattr=+execute-only -mattr=fp-armv8 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE-BE %s
-; RUN: llc -mtriple=thumbv8m.main -arm-execute-only -mattr=fp-armv8 -relocation-model=ropi %s -o - \
+; RUN: llc -mtriple=thumbv8m.main -mattr=+execute-only -mattr=fp-armv8 -relocation-model=ropi %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-XO-ROPI %s
define arm_aapcs_vfpcc float @test_vmov_f32() {
Modified: llvm/trunk/test/CodeGen/ARM/execute-only-big-stack-frame.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/execute-only-big-stack-frame.ll?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/execute-only-big-stack-frame.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/execute-only-big-stack-frame.ll Fri Jun 30 19:55:22 2017
@@ -1,8 +1,8 @@
-; RUN: llc < %s -mtriple=thumbv7m -arm-execute-only -O0 %s -o - \
+; RUN: llc < %s -mtriple=thumbv7m -mattr=+execute-only -O0 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-SUBW-ADDW %s
-; RUN: llc < %s -mtriple=thumbv8m.base -arm-execute-only -O0 %s -o - \
+; RUN: llc < %s -mtriple=thumbv8m.base -mattr=+execute-only -O0 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-MOVW-MOVT-ADD %s
-; RUN: llc < %s -mtriple=thumbv8m.main -arm-execute-only -O0 %s -o - \
+; RUN: llc < %s -mtriple=thumbv8m.main -mattr=+execute-only -O0 %s -o - \
; RUN: | FileCheck --check-prefix=CHECK-SUBW-ADDW %s
define i8 @test_big_stack_frame() {
Modified: llvm/trunk/test/CodeGen/ARM/execute-only-section.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/execute-only-section.ll?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/execute-only-section.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/execute-only-section.ll Fri Jun 30 19:55:22 2017
@@ -1,6 +1,6 @@
-; RUN: llc < %s -mtriple=thumbv7m -arm-execute-only %s -o - | FileCheck %s
-; RUN: llc < %s -mtriple=thumbv8m.base -arm-execute-only %s -o - | FileCheck %s
-; RUN: llc < %s -mtriple=thumbv8m.main -arm-execute-only %s -o - | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7m -mattr=+execute-only %s -o - | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv8m.base -mattr=+execute-only %s -o - | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv8m.main -mattr=+execute-only %s -o - | FileCheck %s
; CHECK: .section .text,"axy",%progbits,unique,0
; CHECK-NOT: .section
Modified: llvm/trunk/test/CodeGen/ARM/execute-only.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/execute-only.ll?rev=306927&r1=306926&r2=306927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/execute-only.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/execute-only.ll Fri Jun 30 19:55:22 2017
@@ -1,6 +1,6 @@
-; RUN: llc -mtriple=thumbv8m.base-eabi -arm-execute-only %s -o - | FileCheck --check-prefix=CHECK --check-prefix=CHECK-T2BASE %s
-; RUN: llc -mtriple=thumbv7m-eabi -arm-execute-only %s -o - | FileCheck --check-prefix=CHECK --check-prefix=CHECK-T2 %s
-; RUN: llc -mtriple=thumbv8m.main-eabi -arm-execute-only %s -o - | FileCheck --check-prefix=CHECK --check-prefix=CHECK-T2 %s
+; RUN: llc -mtriple=thumbv8m.base-eabi -mattr=+execute-only %s -o - | FileCheck --check-prefix=CHECK --check-prefix=CHECK-T2BASE %s
+; RUN: llc -mtriple=thumbv7m-eabi -mattr=+execute-only %s -o - | FileCheck --check-prefix=CHECK --check-prefix=CHECK-T2 %s
+; RUN: llc -mtriple=thumbv8m.main-eabi -mattr=+execute-only %s -o - | FileCheck --check-prefix=CHECK --check-prefix=CHECK-T2 %s
@var = global i32 0
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