[llvm] r319430 - [MC] Function stack size section.
Sean Eveson via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 30 05:05:14 PST 2017
Author: seaneveson
Date: Thu Nov 30 05:05:14 2017
New Revision: 319430
URL: http://llvm.org/viewvc/llvm-project?rev=319430&view=rev
Log:
[MC] Function stack size section.
Re applying after fixing issues in the diff, sorry for any painful conflicts/merges!
Original RFC: http://lists.llvm.org/pipermail/llvm-dev/2017-August/117028.html
This change adds a '.stack-size' section containing metadata on function stack sizes to output ELF files behind the new -stack-size-section flag. The section contains pairs of function symbol references (8 byte) and stack sizes (unsigned LEB128).
The contents of this section can be used to measure changes to stack sizes between different versions of the compiler or a source base. The advantage of having a section is that we can extract this information when examining binaries that we didn't build, and it allows users and tools easy access to that information just by referencing the binary.
There is a follow up change to add an option to clang.
Thanks.
Reviewers: hfinkel, MatzeB
Reviewed By: MatzeB
Subscribers: thegameg, asb, llvm-commits
Differential Revision: https://reviews.llvm.org/D39788
Added:
llvm/trunk/test/CodeGen/X86/stack-size-section.ll
Modified:
llvm/trunk/docs/CodeGenerator.rst
llvm/trunk/docs/CommandGuide/llc.rst
llvm/trunk/include/llvm/CodeGen/AsmPrinter.h
llvm/trunk/include/llvm/CodeGen/CommandFlags.def
llvm/trunk/include/llvm/MC/MCObjectFileInfo.h
llvm/trunk/include/llvm/Target/TargetOptions.h
llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
llvm/trunk/lib/MC/MCObjectFileInfo.cpp
Modified: llvm/trunk/docs/CodeGenerator.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/CodeGenerator.rst?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/docs/CodeGenerator.rst (original)
+++ llvm/trunk/docs/CodeGenerator.rst Thu Nov 30 05:05:14 2017
@@ -1578,6 +1578,17 @@ which lowers MCInst's into machine code
important if you want to support direct .o file emission, or would like to
implement an assembler for your target.
+Emitting function stack size information
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A section containing metadata on function stack sizes will be emitted when
+``TargetLoweringObjectFile::StackSizesSection`` is not null, and
+``TargetOptions::EmitStackSizeSection`` is set (-stack-size-section). The
+section will contain an array of pairs of function symbol references (8 byte)
+and stack sizes (unsigned LEB128). The stack size values only include the space
+allocated in the function prologue. Functions with dynamic stack allocations are
+not included.
+
VLIW Packetizer
---------------
Modified: llvm/trunk/docs/CommandGuide/llc.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/CommandGuide/llc.rst?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/docs/CommandGuide/llc.rst (original)
+++ llvm/trunk/docs/CommandGuide/llc.rst Thu Nov 30 05:05:14 2017
@@ -132,6 +132,14 @@ End-user Options
Specify which EABI version should conform to. Valid EABI versions are *gnu*,
*4* and *5*. Default value (*default*) depends on the triple.
+.. option:: -stack-size-section
+
+ Emit the .stack_sizes section which contains stack size metadata. The section
+ contains an array of pairs of function symbol references (8 byte) and stack
+ sizes (unsigned LEB128). The stack size values only include the space allocated
+ in the function prologue. Functions with dynamic stack allocations are not
+ included.
+
Tuning/Configuration Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Modified: llvm/trunk/include/llvm/CodeGen/AsmPrinter.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/AsmPrinter.h?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/AsmPrinter.h (original)
+++ llvm/trunk/include/llvm/CodeGen/AsmPrinter.h Thu Nov 30 05:05:14 2017
@@ -295,6 +295,8 @@ public:
void emitFrameAlloc(const MachineInstr &MI);
+ void emitStackSizeSection(const MachineFunction &MF);
+
enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
CFIMoveType needsCFIMoves() const;
Modified: llvm/trunk/include/llvm/CodeGen/CommandFlags.def
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/CommandFlags.def?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/CommandFlags.def (original)
+++ llvm/trunk/include/llvm/CodeGen/CommandFlags.def Thu Nov 30 05:05:14 2017
@@ -255,6 +255,10 @@ static cl::opt<DebuggerKind> DebuggerTun
clEnumValN(DebuggerKind::LLDB, "lldb", "lldb"),
clEnumValN(DebuggerKind::SCE, "sce", "SCE targets (e.g. PS4)")));
+static cl::opt<bool> EnableStackSizeSection(
+ "stack-size-section",
+ cl::desc("Emit a section containing stack size metadata"), cl::init(false));
+
// Common utility function tightly tied to the options listed here. Initializes
// a TargetOptions object with CodeGen flags and returns it.
static TargetOptions InitTargetOptionsFromCodeGenFlags() {
@@ -281,6 +285,7 @@ static TargetOptions InitTargetOptionsFr
Options.UniqueSectionNames = UniqueSectionNames;
Options.EmulatedTLS = EmulatedTLS;
Options.ExceptionModel = ExceptionModel;
+ Options.EmitStackSizeSection = EnableStackSizeSection;
Options.MCOptions = InitMCTargetOptionsFromFlags();
Modified: llvm/trunk/include/llvm/MC/MCObjectFileInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCObjectFileInfo.h?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCObjectFileInfo.h (original)
+++ llvm/trunk/include/llvm/MC/MCObjectFileInfo.h Thu Nov 30 05:05:14 2017
@@ -154,6 +154,9 @@ protected:
/// It is initialized on demand so it can be overwritten (with uniquing).
MCSection *EHFrameSection;
+ /// Section containing metadata on function stack sizes.
+ MCSection *StackSizesSection;
+
// ELF specific sections.
MCSection *DataRelROSection;
MCSection *MergeableConst4Section;
@@ -287,6 +290,8 @@ public:
MCSection *getStackMapSection() const { return StackMapSection; }
MCSection *getFaultMapSection() const { return FaultMapSection; }
+ MCSection *getStackSizesSection() const { return StackSizesSection; }
+
// ELF specific sections.
MCSection *getDataRelROSection() const { return DataRelROSection; }
const MCSection *getMergeableConst4Section() const {
Modified: llvm/trunk/include/llvm/Target/TargetOptions.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetOptions.h?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetOptions.h (original)
+++ llvm/trunk/include/llvm/Target/TargetOptions.h Thu Nov 30 05:05:14 2017
@@ -108,7 +108,7 @@ namespace llvm {
DisableIntegratedAS(false), RelaxELFRelocations(false),
FunctionSections(false), DataSections(false),
UniqueSectionNames(true), TrapUnreachable(false), EmulatedTLS(false),
- EnableIPRA(false) {}
+ EnableIPRA(false), EmitStackSizeSection(false) {}
/// PrintMachineCode - This flag is enabled when the -print-machineinstrs
/// option is specified on the command line, and should enable debugging
@@ -216,6 +216,9 @@ namespace llvm {
/// This flag enables InterProcedural Register Allocation (IPRA).
unsigned EnableIPRA : 1;
+ /// Emit section containing metadata on function stack sizes.
+ unsigned EmitStackSizeSection : 1;
+
/// FloatABIType - This setting is set by -float-abi=xxx option is specfied
/// on the command line. This setting may either be Default, Soft, or Hard.
/// Default selects the target's default behavior. Soft selects the ABI for
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Thu Nov 30 05:05:14 2017
@@ -964,6 +964,31 @@ void AsmPrinter::emitFrameAlloc(const Ma
MCConstantExpr::create(FrameOffset, OutContext));
}
+void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
+ if (!MF.getTarget().Options.EmitStackSizeSection)
+ return;
+
+ MCSection *StackSizeSection = getObjFileLowering().getStackSizesSection();
+ if (!StackSizeSection)
+ return;
+
+ const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
+ // Don't emit functions with dynamic stack allocations.
+ if (FrameInfo.hasVarSizedObjects())
+ return;
+
+ OutStreamer->PushSection();
+ OutStreamer->SwitchSection(StackSizeSection);
+
+ const MCSymbol *FunctionSymbol = getSymbol(MF.getFunction());
+ uint64_t StackSize = FrameInfo.getStackSize();
+ OutStreamer->EmitValue(MCSymbolRefExpr::create(FunctionSymbol, OutContext),
+ /* size = */ 8);
+ OutStreamer->EmitULEB128IntValue(StackSize);
+
+ OutStreamer->PopSection();
+}
+
static bool needFuncLabelsForEHOrDebugInfo(const MachineFunction &MF,
MachineModuleInfo *MMI) {
if (!MF.getLandingPads().empty() || MF.hasEHFunclets() || MMI->hasDebugInfo())
@@ -1135,6 +1160,9 @@ void AsmPrinter::EmitFunctionBody() {
HI.Handler->endFunction(MF);
}
+ // Emit section containing stack size metadata.
+ emitStackSizeSection(*MF);
+
if (isVerbose())
OutStreamer->GetCommentOS() << "-- End function\n";
Modified: llvm/trunk/lib/MC/MCObjectFileInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCObjectFileInfo.cpp?rev=319430&r1=319429&r2=319430&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCObjectFileInfo.cpp (original)
+++ llvm/trunk/lib/MC/MCObjectFileInfo.cpp Thu Nov 30 05:05:14 2017
@@ -594,6 +594,8 @@ void MCObjectFileInfo::initELFMCObjectFi
EHFrameSection =
Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
+
+ StackSizesSection = Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, 0);
}
void MCObjectFileInfo::initCOFFMCObjectFileInfo(const Triple &T) {
Added: llvm/trunk/test/CodeGen/X86/stack-size-section.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/stack-size-section.ll?rev=319430&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/stack-size-section.ll (added)
+++ llvm/trunk/test/CodeGen/X86/stack-size-section.ll Thu Nov 30 05:05:14 2017
@@ -0,0 +1,30 @@
+; RUN: llc < %s -mtriple=x86_64-linux -stack-size-section | FileCheck %s
+
+; CHECK-LABEL: func1:
+; CHECK: .section .stack_sizes,"", at progbits
+; CHECK-NEXT: .quad func1
+; CHECK-NEXT: .byte 8
+define void @func1(i32, i32) #0 {
+ alloca i32, align 4
+ alloca i32, align 4
+ ret void
+}
+
+; CHECK-LABEL: func2:
+; CHECK: .section .stack_sizes,"", at progbits
+; CHECK-NEXT: .quad func2
+; CHECK-NEXT: .byte 24
+define void @func2() #0 {
+ alloca i32, align 4
+ call void @func1(i32 1, i32 2)
+ ret void
+}
+
+; CHECK-LABEL: dynalloc:
+; CHECK-NOT: .section .stack_sizes
+define void @dynalloc(i32 %N) #0 {
+ alloca i32, i32 %N
+ ret void
+}
+
+attributes #0 = { "no-frame-pointer-elim"="true" }
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