[llvm] r306010 - [X86] Add support for "probe-stack" attribute
whitequark via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 22 08:42:54 PDT 2017
Author: whitequark
Date: Thu Jun 22 10:42:53 2017
New Revision: 306010
URL: http://llvm.org/viewvc/llvm-project?rev=306010&view=rev
Log:
[X86] Add support for "probe-stack" attribute
This commit adds prologue code emission for stack probe function
calls.
Reviewed By: majnemer
Differential Revision: https://reviews.llvm.org/D34387
Added:
llvm/trunk/test/CodeGen/X86/stack-probe-red-zone.ll
llvm/trunk/test/CodeGen/X86/stack-probes.ll
Modified:
llvm/trunk/include/llvm/Target/TargetLowering.h
llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
llvm/trunk/lib/Target/X86/X86ISelLowering.h
Modified: llvm/trunk/include/llvm/Target/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetLowering.h?rev=306010&r1=306009&r2=306010&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetLowering.h (original)
+++ llvm/trunk/include/llvm/Target/TargetLowering.h Thu Jun 22 10:42:53 2017
@@ -1374,6 +1374,12 @@ public:
/// Returns the target-specific address of the unsafe stack pointer.
virtual Value *getSafeStackPointerLocation(IRBuilder<> &IRB) const;
+ /// Returns the name of the symbol used to emit stack probes or the empty
+ /// string if not applicable.
+ virtual StringRef getStackProbeSymbolName(MachineFunction &MF) const {
+ return "";
+ }
+
/// Returns true if a cast between SrcAS and DestAS is a noop.
virtual bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const {
return false;
Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=306010&r1=306009&r2=306010&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Thu Jun 22 10:42:53 2017
@@ -748,17 +748,7 @@ void X86FrameLowering::emitStackProbeCal
else
CallOp = X86::CALLpcrel32;
- const char *Symbol;
- if (Is64Bit) {
- if (STI.isTargetCygMing()) {
- Symbol = "___chkstk_ms";
- } else {
- Symbol = "__chkstk";
- }
- } else if (STI.isTargetCygMing())
- Symbol = "_alloca";
- else
- Symbol = "_chkstk";
+ StringRef Symbol = STI.getTargetLowering()->getStackProbeSymbolName(MF);
MachineInstrBuilder CI;
MachineBasicBlock::iterator ExpansionMBBI = std::prev(MBBI);
@@ -769,10 +759,11 @@ void X86FrameLowering::emitStackProbeCal
// For the large code model, we have to call through a register. Use R11,
// as it is scratch in all supported calling conventions.
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::R11)
- .addExternalSymbol(Symbol);
+ .addExternalSymbol(MF.createExternalSymbolName(Symbol));
CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addReg(X86::R11);
} else {
- CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addExternalSymbol(Symbol);
+ CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp))
+ .addExternalSymbol(MF.createExternalSymbolName(Symbol));
}
unsigned AX = Is64Bit ? X86::RAX : X86::EAX;
@@ -783,13 +774,13 @@ void X86FrameLowering::emitStackProbeCal
.addReg(SP, RegState::Define | RegState::Implicit)
.addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
- if (Is64Bit) {
+ if (!STI.isTargetWin32()) {
// MSVC x64's __chkstk and cygwin/mingw's ___chkstk_ms do not adjust %rsp
// themselves. It also does not clobber %rax so we can reuse it when
// adjusting %rsp.
- BuildMI(MBB, MBBI, DL, TII.get(X86::SUB64rr), X86::RSP)
- .addReg(X86::RSP)
- .addReg(X86::RAX);
+ BuildMI(MBB, MBBI, DL, TII.get(getSUBrrOpcode(Is64Bit)), SP)
+ .addReg(SP)
+ .addReg(AX);
}
if (InProlog) {
@@ -978,7 +969,8 @@ void X86FrameLowering::emitPrologue(Mach
X86FI->setCalleeSavedFrameSize(
X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta);
- bool UseStackProbe = (STI.isOSWindows() && !STI.isTargetMachO());
+ bool UseRedZone = false;
+ bool UseStackProbe = !STI.getTargetLowering()->getStackProbeSymbolName(MF).empty();
// The default stack probe size is 4096 if the function has no stackprobesize
// attribute.
@@ -1007,6 +999,7 @@ void X86FrameLowering::emitPrologue(Mach
!TRI->needsStackRealignment(MF) &&
!MFI.hasVarSizedObjects() && // No dynamic alloca.
!MFI.adjustsStack() && // No calls.
+ !UseStackProbe && // No stack probes.
!IsWin64CC && // Win64 has no Red Zone
!MFI.hasCopyImplyingStackAdjustment() && // Don't push and pop.
!MF.shouldSplitStack()) { // Regular stack
@@ -1015,6 +1008,7 @@ void X86FrameLowering::emitPrologue(Mach
X86FI->setUsesRedZone(MinSize > 0 || StackSize > 0);
StackSize = std::max(MinSize, StackSize > 128 ? StackSize - 128 : 0);
MFI.setStackSize(StackSize);
+ UseRedZone = true;
}
// Insert stack pointer adjustment for later moving of return addr. Only
@@ -1192,6 +1186,8 @@ void X86FrameLowering::emitPrologue(Mach
if (IsWin64Prologue && !IsFunclet && TRI->needsStackRealignment(MF))
AlignedNumBytes = alignTo(AlignedNumBytes, MaxAlign);
if (AlignedNumBytes >= StackProbeSize && UseStackProbe) {
+ assert(!UseRedZone && "The Red Zone is not accounted for in stack probes");
+
// Check whether EAX is livein for this block.
bool isEAXAlive = isEAXLiveIn(MBB);
Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=306010&r1=306009&r2=306010&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu Jun 22 10:42:53 2017
@@ -18651,8 +18651,9 @@ X86TargetLowering::LowerDYNAMIC_STACKALL
SelectionDAG &DAG) const {
MachineFunction &MF = DAG.getMachineFunction();
bool SplitStack = MF.shouldSplitStack();
+ bool EmitStackProbe = !getStackProbeSymbolName(MF).empty();
bool Lower = (Subtarget.isOSWindows() && !Subtarget.isTargetMachO()) ||
- SplitStack;
+ SplitStack || EmitStackProbe;
SDLoc dl(Op);
// Get the inputs.
@@ -36390,3 +36391,22 @@ void X86TargetLowering::insertCopiesSpli
bool X86TargetLowering::supportSwiftError() const {
return Subtarget.is64Bit();
}
+
+/// Returns the name of the symbol used to emit stack probes or the empty
+/// string if not applicable.
+StringRef X86TargetLowering::getStackProbeSymbolName(MachineFunction &MF) const {
+ // If the function specifically requests stack probes, emit them.
+ if (MF.getFunction()->hasFnAttribute("probe-stack"))
+ return MF.getFunction()->getFnAttribute("probe-stack").getValueAsString();
+
+ // Generally, if we aren't on Windows, the platform ABI does not include
+ // support for stack probes, so don't emit them.
+ if (!Subtarget.isOSWindows() || Subtarget.isTargetMachO())
+ return "";
+
+ // We need a stack probe to conform to the Windows ABI. Choose the right
+ // symbol.
+ if (Subtarget.is64Bit())
+ return Subtarget.isTargetCygMing() ? "___chkstk_ms" : "__chkstk";
+ return Subtarget.isTargetCygMing() ? "_alloca" : "_chkstk";
+}
Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.h?rev=306010&r1=306009&r2=306010&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.h (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.h Thu Jun 22 10:42:53 2017
@@ -1059,6 +1059,8 @@ namespace llvm {
bool supportSwiftError() const override;
+ StringRef getStackProbeSymbolName(MachineFunction &MF) const override;
+
unsigned getMaxSupportedInterleaveFactor() const override { return 4; }
/// \brief Lower interleaved load(s) into target specific
Added: llvm/trunk/test/CodeGen/X86/stack-probe-red-zone.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/stack-probe-red-zone.ll?rev=306010&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/stack-probe-red-zone.ll (added)
+++ llvm/trunk/test/CodeGen/X86/stack-probe-red-zone.ll Thu Jun 22 10:42:53 2017
@@ -0,0 +1,21 @@
+; RUN: llc -mtriple=x86_64-pc-linux-gnu < %s -o - | FileCheck %s
+
+; Ensure that red zone usage occurs.
+define void @testStackProbesOff() {
+ %array = alloca [40096 x i8], align 16
+ ret void
+
+; CHECK-LABEL: testStackProbesOff:
+; CHECK: subq $39976, %rsp # imm = 0x9C28
+}
+
+; Ensure stack probes do not result in red zone usage.
+define void @testStackProbesOn() "probe-stack"="__probestack" {
+ %array = alloca [40096 x i8], align 16
+ ret void
+
+; CHECK-LABEL: testStackProbesOn:
+; CHECK: movl $40104, %eax # imm = 0x9CA8
+; CHECK-NEXT: callq __probestack
+; CHECK-NEXT: subq %rax, %rsp
+}
Added: llvm/trunk/test/CodeGen/X86/stack-probes.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/stack-probes.ll?rev=306010&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/stack-probes.ll (added)
+++ llvm/trunk/test/CodeGen/X86/stack-probes.ll Thu Jun 22 10:42:53 2017
@@ -0,0 +1,29 @@
+; RUN: llc -mtriple=i386-pc-linux-gnu < %s -o - | FileCheck --check-prefix=X86-LINUX %s
+; RUN: llc -mtriple=x86_64-pc-linux-gnu < %s -o - | FileCheck --check-prefix=X64-LINUX %s
+; RUN: llc -mtriple=x86_64-pc-linux-gnu -code-model=large < %s -o - | FileCheck --check-prefix=X64-LINUX-LARGE %s
+
+declare void @use([40096 x i8]*)
+
+; Ensure calls to __probestack occur for large stack frames
+define void @test() "probe-stack"="__probestack" {
+ %array = alloca [40096 x i8], align 16
+ call void @use([40096 x i8]* %array)
+ ret void
+
+; X86-LINUX-LABEL: test:
+; X86-LINUX: movl $40124, %eax # imm = 0x9CBC
+; X86-LINUX-NEXT: calll __probestack
+; X86-LINUX-NEXT: subl %eax, %esp
+
+; X64-LINUX-LABEL: test:
+; X64-LINUX: movl $40104, %eax # imm = 0x9CA8
+; X64-LINUX-NEXT: callq __probestack
+; X64-LINUX-NEXT: subq %rax, %rsp
+
+; X64-LINUX-LARGE-LABEL: test:
+; X64-LINUX-LARGE: movl $40104, %eax # imm = 0x9CA8
+; X64-LINUX-LARGE-NEXT: movabsq $__probestack, %r11
+; X64-LINUX-LARGE-NEXT: callq *%r11
+; X64-LINUX-LARGE-NEXT: subq %rax, %rsp
+
+}
More information about the llvm-commits
mailing list