[llvm] 4f9929a - [AIX][CodeGen] Storage Locations for Constant Pointers
Qiongsi Wu via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 23 06:46:16 PDT 2023
Author: Qiongsi Wu
Date: 2023-03-23T09:44:47-04:00
New Revision: 4f9929add5369490c9607fc9203761483d2bc916
URL: https://github.com/llvm/llvm-project/commit/4f9929add5369490c9607fc9203761483d2bc916
DIFF: https://github.com/llvm/llvm-project/commit/4f9929add5369490c9607fc9203761483d2bc916.diff
LOG: [AIX][CodeGen] Storage Locations for Constant Pointers
This patch adds an `llc` option `-mroptr` to specify storage locations for constant pointers on AIX.
When the `-mroptr` option is specified, constant pointers, virtual function tables, and virtual type tables are placed in read-only storage. Otherwise, by default, pointers, virtual function tables, and virtual type tables are placed are placed in read/write storage.
https://reviews.llvm.org/D144190 enables the `-mroptr` option for `clang`.
Reviewed By: hubert.reinterpretcast, stephenpeckham, myhsu, MaskRay, serge-sans-paille
Differential Revision: https://reviews.llvm.org/D144189
Added:
llvm/test/CodeGen/PowerPC/aix-xcoff-roptr.ll
llvm/test/CodeGen/PowerPC/aix64-xcoff-roptr.ll
Modified:
llvm/docs/ReleaseNotes.rst
llvm/include/llvm/CodeGen/CommandFlags.h
llvm/include/llvm/Target/TargetOptions.h
llvm/lib/CodeGen/CommandFlags.cpp
llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
llvm/tools/llc/llc.cpp
Removed:
################################################################################
diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 525f57a90dfb0..6f78497644479 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -122,7 +122,11 @@ Changes to the MIPS Backend
Changes to the PowerPC Backend
------------------------------
-* ...
+* A new option ``-mroptr`` is added to ``clang`` and ``llc``. When this option
+ is present, constant objects with relocatable address values are put into the
+ RO data section. This option should be used with the ``-fdata-sections``
+ option, and is not supported with ``-fno-data-sections``. The option is
+ only supported on AIX.
Changes to the RISC-V Backend
-----------------------------
diff --git a/llvm/include/llvm/CodeGen/CommandFlags.h b/llvm/include/llvm/CodeGen/CommandFlags.h
index 475d87bdd5b13..19b466629dbfc 100644
--- a/llvm/include/llvm/CodeGen/CommandFlags.h
+++ b/llvm/include/llvm/CodeGen/CommandFlags.h
@@ -143,6 +143,8 @@ unsigned getAlignLoops();
bool getJMCInstrument();
+bool getXCOFFReadOnlyPointers();
+
/// Create this object with static storage to register codegen-related command
/// line options.
struct RegisterCodeGenFlags {
diff --git a/llvm/include/llvm/Target/TargetOptions.h b/llvm/include/llvm/Target/TargetOptions.h
index 22e811653c6d4..76e4248088afd 100644
--- a/llvm/include/llvm/Target/TargetOptions.h
+++ b/llvm/include/llvm/Target/TargetOptions.h
@@ -130,13 +130,12 @@ namespace llvm {
HonorSignDependentRoundingFPMathOption(false), NoZerosInBSS(false),
GuaranteedTailCallOpt(false), StackSymbolOrdering(true),
EnableFastISel(false), EnableGlobalISel(false), UseInitArray(false),
- DisableIntegratedAS(false),
- RelaxELFRelocations(true), FunctionSections(false),
- DataSections(false), IgnoreXCOFFVisibility(false),
- XCOFFTracebackTable(true), UniqueSectionNames(true),
- UniqueBasicBlockSectionNames(false), TrapUnreachable(false),
- NoTrapAfterNoreturn(false), TLSSize(0), EmulatedTLS(false),
- ExplicitEmulatedTLS(false), EnableIPRA(false),
+ DisableIntegratedAS(false), RelaxELFRelocations(true),
+ FunctionSections(false), DataSections(false),
+ IgnoreXCOFFVisibility(false), XCOFFTracebackTable(true),
+ UniqueSectionNames(true), UniqueBasicBlockSectionNames(false),
+ TrapUnreachable(false), NoTrapAfterNoreturn(false), TLSSize(0),
+ EmulatedTLS(false), ExplicitEmulatedTLS(false), EnableIPRA(false),
EmitStackSizeSection(false), EnableMachineOutliner(false),
EnableMachineFunctionSplitter(false), SupportsDefaultOutlining(false),
EmitAddrsig(false), EmitCallSiteInfo(false),
@@ -144,7 +143,7 @@ namespace llvm {
ValueTrackingVariableLocations(false), ForceDwarfFrameSection(false),
XRayOmitFunctionIndex(false), DebugStrictDwarf(false),
Hotpatch(false), PPCGenScalarMASSEntries(false), JMCInstrument(false),
- EnableCFIFixup(false), MisExpect(false),
+ EnableCFIFixup(false), MisExpect(false), XCOFFReadOnlyPointers(false),
FPDenormalMode(DenormalMode::IEEE, DenormalMode::IEEE) {}
/// DisableFramePointerElim - This returns true if frame pointer elimination
@@ -360,6 +359,10 @@ namespace llvm {
/// By default, it is set to false
unsigned MisExpect : 1;
+ /// When set to true, const objects with relocatable address values are put
+ /// into the RO data section.
+ unsigned XCOFFReadOnlyPointers : 1;
+
/// Name of the stack usage file (i.e., .su file) if user passes
/// -fstack-usage. If empty, it can be implied that -fstack-usage is not
/// passed on the command line.
diff --git a/llvm/lib/CodeGen/CommandFlags.cpp b/llvm/lib/CodeGen/CommandFlags.cpp
index 51d259cea41b8..5ef650787a585 100644
--- a/llvm/lib/CodeGen/CommandFlags.cpp
+++ b/llvm/lib/CodeGen/CommandFlags.cpp
@@ -103,6 +103,7 @@ CGOPT(bool, XRayOmitFunctionIndex)
CGOPT(bool, DebugStrictDwarf)
CGOPT(unsigned, AlignLoops)
CGOPT(bool, JMCInstrument)
+CGOPT(bool, XCOFFReadOnlyPointers)
codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
#define CGBINDOPT(NAME) \
@@ -478,6 +479,13 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
cl::init(false));
CGBINDOPT(JMCInstrument);
+ static cl::opt<bool> XCOFFReadOnlyPointers(
+ "mroptr",
+ cl::desc("When set to true, const objects with relocatable address "
+ "values are put into the RO data section."),
+ cl::init(false));
+ CGBINDOPT(XCOFFReadOnlyPointers);
+
#undef CGBINDOPT
mc::RegisterMCTargetOptionsFlags();
@@ -554,6 +562,7 @@ codegen::InitTargetOptionsFromCodeGenFlags(const Triple &TheTriple) {
Options.DebugStrictDwarf = getDebugStrictDwarf();
Options.LoopAlignment = getAlignLoops();
Options.JMCInstrument = getJMCInstrument();
+ Options.XCOFFReadOnlyPointers = getXCOFFReadOnlyPointers();
Options.MCOptions = mc::InitMCTargetOptionsFromFlags();
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index e2fbe027f15b0..c81b6bb623b96 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -2343,8 +2343,11 @@ MCSection *TargetLoweringObjectFileXCOFF::getExplicitSectionGlobal(
XCOFF::StorageMappingClass MappingClass;
if (Kind.isText())
MappingClass = XCOFF::XMC_PR;
- else if (Kind.isData() || Kind.isReadOnlyWithRel() || Kind.isBSS())
+ else if (Kind.isData() || Kind.isBSS())
MappingClass = XCOFF::XMC_RW;
+ else if (Kind.isReadOnlyWithRel())
+ MappingClass =
+ TM.Options.XCOFFReadOnlyPointers ? XCOFF::XMC_RO : XCOFF::XMC_RW;
else if (Kind.isReadOnly())
MappingClass = XCOFF::XMC_RO;
else
@@ -2429,9 +2432,18 @@ MCSection *TargetLoweringObjectFileXCOFF::SelectSectionForGlobal(
return TextSection;
}
- // TODO: We may put Kind.isReadOnlyWithRel() under option control, because
- // user may want to have read-only data with relocations placed into a
- // read-only section by the compiler.
+ if (TM.Options.XCOFFReadOnlyPointers && Kind.isReadOnlyWithRel()) {
+ if (!TM.getDataSections())
+ report_fatal_error(
+ "ReadOnlyPointers is supported only if data sections is turned on");
+
+ SmallString<128> Name;
+ getNameWithPrefix(Name, GO, TM);
+ return getContext().getXCOFFSection(
+ Name, SectionKind::getReadOnly(),
+ XCOFF::CsectProperties(XCOFF::XMC_RO, XCOFF::XTY_SD));
+ }
+
// For BSS kind, zero initialized data must be emitted to the .data section
// because external linkage control sections that get mapped to the .bss
// section will be linked as tentative defintions, which is only appropriate
diff --git a/llvm/test/CodeGen/PowerPC/aix-xcoff-roptr.ll b/llvm/test/CodeGen/PowerPC/aix-xcoff-roptr.ll
new file mode 100644
index 0000000000000..532d17e087e5b
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/aix-xcoff-roptr.ll
@@ -0,0 +1,30 @@
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -mroptr < %s | FileCheck %s
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -mroptr -filetype=obj -o %t.o < %s
+; RUN: llvm-objdump -t --symbol-description %t.o | FileCheck %s --check-prefix=OBJ
+
+; RUN: not llc -mtriple powerpc-ibm-aix-xcoff -mroptr -data-sections=false \
+; RUN: < %s 2>&1 | FileCheck %s --check-prefix=DS_ERR
+
+; DS_ERR: -mroptr option must be used with -data-sections
+
+%union.U = type { %"struct.U::A" }
+%"struct.U::A" = type { ptr }
+
+ at _ZL1p = internal constant i32 ptrtoint (ptr @_ZL1p to i32), align 4
+; CHECK: .csect _ZL1p[RO],2
+; CHECK-NEXT: .lglobl _ZL1p[RO]
+; CHECK-NEXT: .align 2
+; CHECK-NEXT: .vbyte 4, _ZL1p[RO]
+; OBJ-DAG: {{([[:xdigit:]]{8})}} l .text {{([[:xdigit:]]{8})}} (idx: [[#]]) _ZL1p[RO]
+ at q = thread_local constant ptr @_ZL1p, align 4
+; CHECK: .csect q[TL],2
+; CHECK-NEXT: .globl q[TL]
+; CHECK-NEXT: .align 2
+; CHECK-NEXT: .vbyte 4, _ZL1p[RO]
+; OBJ-DAG: {{([[:xdigit:]]{8})}} g O .tdata {{([[:xdigit:]]{8})}} (idx: [[#]]) q[TL]
+ at u = local_unnamed_addr constant [1 x %union.U] [%union.U { %"struct.U::A" { ptr @_ZL1p } }], align 4
+; CHECK: .csect u[RO],2
+; CHECK-NEXT: .globl u[RO]
+; CHECK-NEXT: .align 2
+; CHECK-NEXT: .vbyte 4, _ZL1p[RO]
+; OBJ-DAG: {{([[:xdigit:]]{8})}} g .text {{([[:xdigit:]]{8})}} (idx: [[#]]) u[RO]
diff --git a/llvm/test/CodeGen/PowerPC/aix64-xcoff-roptr.ll b/llvm/test/CodeGen/PowerPC/aix64-xcoff-roptr.ll
new file mode 100644
index 0000000000000..aff753661b0e1
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/aix64-xcoff-roptr.ll
@@ -0,0 +1,33 @@
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -mroptr < %s | FileCheck %s
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -mroptr -filetype=obj -o %t.o < %s
+; RUN: llvm-objdump -t --symbol-description %t.o | FileCheck %s --check-prefix=OBJ
+
+; RUN: not llc -mtriple powerpc64-ibm-aix-xcoff -mroptr -data-sections=false \
+; RUN: < %s 2>&1 | FileCheck %s --check-prefix=DS_ERR
+; RUN: not llc -mtriple powerpc64le-unknown-linux-gnu -mroptr \
+; RUN: < %s 2>&1 | FileCheck %s --check-prefix=OS_ERR
+
+; DS_ERR: -mroptr option must be used with -data-sections
+; OS_ERR: -mroptr option is only supported on AIX
+
+%union.U = type { %"struct.U::A" }
+%"struct.U::A" = type { ptr }
+
+ at _ZL1p = internal constant i64 ptrtoint (ptr @_ZL1p to i64), align 8
+; CHECK: .csect _ZL1p[RO],3
+; CHECK-NEXT: .lglobl _ZL1p[RO]
+; CHECK-NEXT: .align 3
+; CHECK-NEXT: .vbyte 8, _ZL1p[RO]
+; OBJ-DAG: {{([[:xdigit:]]{16})}} l .text {{([[:xdigit:]]{16})}} (idx: [[#]]) _ZL1p[RO]
+ at q = thread_local constant ptr @_ZL1p, align 8
+; CHECK: .csect q[TL],3
+; CHECK-NEXT: .globl q[TL]
+; CHECK-NEXT: .align 3
+; CHECK-NEXT: .vbyte 8, _ZL1p[RO]
+; OBJ-DAG: {{([[:xdigit:]]{16})}} g O .tdata {{([[:xdigit:]]{16})}} (idx: [[#]]) q[TL]
+ at u = local_unnamed_addr constant [1 x %union.U] [%union.U { %"struct.U::A" { ptr @_ZL1p } }], align 8
+; CHECK: .csect u[RO],3
+; CHECK-NEXT: .globl u[RO]
+; CHECK-NEXT: .align 3
+; CHECK-NEXT: .vbyte 8, _ZL1p[RO]
+; OBJ-DAG: {{([[:xdigit:]]{16})}} g .text {{([[:xdigit:]]{16})}} (idx: [[#]]) u[RO]
diff --git a/llvm/tools/llc/llc.cpp b/llvm/tools/llc/llc.cpp
index ed65b83487790..860fa39d57e8a 100644
--- a/llvm/tools/llc/llc.cpp
+++ b/llvm/tools/llc/llc.cpp
@@ -496,6 +496,24 @@ static int compileModule(char **argv, LLVMContext &Context) {
TargetOptions Options;
auto InitializeOptions = [&](const Triple &TheTriple) {
Options = codegen::InitTargetOptionsFromCodeGenFlags(TheTriple);
+
+ if (Options.XCOFFReadOnlyPointers) {
+ if (!TheTriple.isOSAIX())
+ reportError("-mroptr option is only supported on AIX", InputFilename);
+
+ // Since the storage mapping class is specified per csect,
+ // without using data sections, it is less effective to use read-only
+ // pointers. Using read-only pointers may cause other RO variables in the
+ // same csect to become RW when the linker acts upon `-bforceimprw`;
+ // therefore, we require that separate data sections are used in the
+ // presence of ReadOnlyPointers. We respect the setting of data-sections
+ // since we have not found reasons to do otherwise that overcome the user
+ // surprise of not respecting the setting.
+ if (!Options.DataSections)
+ reportError("-mroptr option must be used with -data-sections",
+ InputFilename);
+ }
+
Options.BinutilsVersion =
TargetMachine::parseBinutilsVersion(BinutilsVersion);
Options.DisableIntegratedAS = NoIntegratedAssembler;
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