[llvm] r269828 - X86: Avoid using _chkstk when lowering WIN_ALLOCA instructions
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Tue May 17 14:06:37 PDT 2016
Already reverted in r269833. Sorry for the breakage.
On Tue, May 17, 2016 at 1:53 PM, Mike Aizatsky via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Hans,
>
> It seems your change broke sanitizer-windows bot. Could you take a look?
>
> http://lab.llvm.org:8011/builders/sanitizer-windows/builds/22232
>
> http://lab.llvm.org:8011/builders/sanitizer-windows/builds/22232/steps/run%20tests/logs/stdio
>
>
>
> On Tue, May 17, 2016 at 1:19 PM Hans Wennborg via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: hans
>> Date: Tue May 17 15:13:29 2016
>> New Revision: 269828
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=269828&view=rev
>> Log:
>> X86: Avoid using _chkstk when lowering WIN_ALLOCA instructions
>>
>> This patch moves the expansion of WIN_ALLOCA pseudo-instructions
>> into a separate pass that walks the CFG and lowers the instructions
>> based on a conservative estimate of the offset between the stack
>> pointer and the lowest accessed stack address.
>>
>> The goal is to reduce binary size and run-time costs by removing
>> calls to _chkstk. While it doesn't fix all the code quality problems
>> with inalloca calls, it's an incremental improvement for PR27076.
>>
>> Differential Revision: http://reviews.llvm.org/D20263
>>
>> Added:
>> llvm/trunk/lib/Target/X86/X86WinAllocaExpander.cpp
>> llvm/trunk/test/CodeGen/X86/win-alloca-expander.ll
>> Modified:
>> llvm/trunk/lib/Target/X86/CMakeLists.txt
>> llvm/trunk/lib/Target/X86/X86.h
>> llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>> llvm/trunk/lib/Target/X86/X86ISelLowering.h
>> llvm/trunk/lib/Target/X86/X86InstrCompiler.td
>> llvm/trunk/lib/Target/X86/X86InstrInfo.td
>> llvm/trunk/lib/Target/X86/X86MachineFunctionInfo.h
>> llvm/trunk/lib/Target/X86/X86TargetMachine.cpp
>> llvm/trunk/test/CodeGen/X86/cleanuppad-inalloca.ll
>> llvm/trunk/test/CodeGen/X86/dynamic-alloca-in-entry.ll
>> llvm/trunk/test/CodeGen/X86/inalloca-ctor.ll
>> llvm/trunk/test/CodeGen/X86/inalloca-invoke.ll
>> llvm/trunk/test/CodeGen/X86/inalloca-stdcall.ll
>> llvm/trunk/test/CodeGen/X86/inalloca.ll
>> llvm/trunk/test/CodeGen/X86/shrink-wrap-chkstk.ll
>>
>> Modified: llvm/trunk/lib/Target/X86/CMakeLists.txt
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/CMakeLists.txt?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/CMakeLists.txt (original)
>> +++ llvm/trunk/lib/Target/X86/CMakeLists.txt Tue May 17 15:13:29 2016
>> @@ -37,6 +37,7 @@ set(sources
>> X86WinEHState.cpp
>> X86OptimizeLEAs.cpp
>> X86FixupBWInsts.cpp
>> + X86WinAllocaExpander.cpp
>> )
>>
>> add_llvm_target(X86CodeGen ${sources})
>>
>> Modified: llvm/trunk/lib/Target/X86/X86.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86.h?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86.h (original)
>> +++ llvm/trunk/lib/Target/X86/X86.h Tue May 17 15:13:29 2016
>> @@ -59,6 +59,9 @@ FunctionPass *createX86FixupLEAs();
>> /// recalculations.
>> FunctionPass *createX86OptimizeLEAs();
>>
>> +/// Return a pass that expands WinAlloca pseudo-instructions.
>> +FunctionPass *createX86WinAllocaExpander();
>> +
>> /// Return a pass that optimizes the code-size of x86 call sequences.
>> This is
>> /// done by replacing esp-relative movs with pushes.
>> FunctionPass *createX86CallFrameOptimization();
>>
>> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Tue May 17 15:13:29 2016
>> @@ -16563,14 +16563,9 @@ X86TargetLowering::LowerDYNAMIC_STACKALL
>> Result = DAG.getNode(X86ISD::SEG_ALLOCA, dl, SPTy, Chain,
>> DAG.getRegister(Vreg, SPTy));
>> } else {
>> - SDValue Flag;
>> - const unsigned Reg = (Subtarget.isTarget64BitLP64() ? X86::RAX :
>> X86::EAX);
>> -
>> - Chain = DAG.getCopyToReg(Chain, dl, Reg, Size, Flag);
>> - Flag = Chain.getValue(1);
>> SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
>> -
>> - Chain = DAG.getNode(X86ISD::WIN_ALLOCA, dl, NodeTys, Chain, Flag);
>> + Chain = DAG.getNode(X86ISD::WIN_ALLOCA, dl, NodeTys, Chain, Size);
>> + MF.getInfo<X86MachineFunctionInfo>()->setHasWinAlloca(true);
>>
>> const X86RegisterInfo *RegInfo = Subtarget.getRegisterInfo();
>> unsigned SPReg = RegInfo->getStackRegister();
>> @@ -23228,18 +23223,6 @@ X86TargetLowering::EmitLoweredSegAlloca(
>> }
>>
>> MachineBasicBlock *
>> -X86TargetLowering::EmitLoweredWinAlloca(MachineInstr *MI,
>> - MachineBasicBlock *BB) const {
>> - assert(!Subtarget.isTargetMachO());
>> - DebugLoc DL = MI->getDebugLoc();
>> - MachineInstr *ResumeMI = Subtarget.getFrameLowering()->emitStackProbe(
>> - *BB->getParent(), *BB, MI, DL, false);
>> - MachineBasicBlock *ResumeBB = ResumeMI->getParent();
>> - MI->eraseFromParent(); // The pseudo instruction is gone now.
>> - return ResumeBB;
>> -}
>> -
>> -MachineBasicBlock *
>> X86TargetLowering::EmitLoweredCatchRet(MachineInstr *MI,
>> MachineBasicBlock *BB) const {
>> MachineFunction *MF = BB->getParent();
>> @@ -23701,8 +23684,6 @@ X86TargetLowering::EmitInstrWithCustomIn
>> case X86::TLS_base_addr32:
>> case X86::TLS_base_addr64:
>> return EmitLoweredTLSAddr(MI, BB);
>> - case X86::WIN_ALLOCA:
>> - return EmitLoweredWinAlloca(MI, BB);
>> case X86::CATCHRET:
>> return EmitLoweredCatchRet(MI, BB);
>> case X86::CATCHPAD:
>>
>> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.h?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86ISelLowering.h (original)
>> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.h Tue May 17 15:13:29 2016
>> @@ -1162,9 +1162,6 @@ namespace llvm {
>> MachineBasicBlock *EmitLoweredAtomicFP(MachineInstr *I,
>> MachineBasicBlock *BB) const;
>>
>> - MachineBasicBlock *EmitLoweredWinAlloca(MachineInstr *MI,
>> - MachineBasicBlock *BB)
>> const;
>> -
>> MachineBasicBlock *EmitLoweredCatchRet(MachineInstr *MI,
>> MachineBasicBlock *BB) const;
>>
>>
>> Modified: llvm/trunk/lib/Target/X86/X86InstrCompiler.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrCompiler.td?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86InstrCompiler.td (original)
>> +++ llvm/trunk/lib/Target/X86/X86InstrCompiler.td Tue May 17 15:13:29 2016
>> @@ -99,18 +99,6 @@ def VAARG_64 : I<0, Pseudo,
>> (X86vaarg64 addr:$ap, imm:$size, imm:$mode,
>> imm:$align)),
>> (implicit EFLAGS)]>;
>>
>> -// Dynamic stack allocation yields a _chkstk or _alloca call for all
>> Windows
>> -// targets. These calls are needed to probe the stack when allocating
>> more than
>> -// 4k bytes in one go. Touching the stack at 4K increments is necessary
>> to
>> -// ensure that the guard pages used by the OS virtual memory manager are
>> -// allocated in correct sequence.
>> -// The main point of having separate instruction are extra unmodelled
>> effects
>> -// (compared to ordinary calls) like stack pointer change.
>> -
>> -let Defs = [EAX, ESP, EFLAGS], Uses = [ESP] in
>> - def WIN_ALLOCA : I<0, Pseudo, (outs), (ins),
>> - "# dynamic stack allocation",
>> - [(X86WinAlloca)]>;
>>
>> // When using segmented stacks these are lowered into instructions which
>> first
>> // check if the current stacklet has enough free memory. If it does,
>> memory is
>> @@ -132,6 +120,27 @@ def SEG_ALLOCA_64 : I<0, Pseudo, (outs G
>> Requires<[In64BitMode]>;
>> }
>>
>> +// Dynamic stack allocation yields a _chkstk or _alloca call for all
>> Windows
>> +// targets. These calls are needed to probe the stack when allocating
>> more than
>> +// 4k bytes in one go. Touching the stack at 4K increments is necessary
>> to
>> +// ensure that the guard pages used by the OS virtual memory manager are
>> +// allocated in correct sequence.
>> +// The main point of having separate instruction are extra unmodelled
>> effects
>> +// (compared to ordinary calls) like stack pointer change.
>> +
>> +let Defs = [EAX, ESP, EFLAGS], Uses = [ESP] in
>> +def WIN_ALLOCA_32 : I<0, Pseudo, (outs), (ins GR32:$size),
>> + "# dynamic stack allocation",
>> + [(X86WinAlloca GR32:$size)]>,
>> + Requires<[NotLP64]>;
>> +
>> +let Defs = [RAX, RSP, EFLAGS], Uses = [RSP] in
>> +def WIN_ALLOCA_64 : I<0, Pseudo, (outs), (ins GR64:$size),
>> + "# dynamic stack allocation",
>> + [(X86WinAlloca GR64:$size)]>,
>> + Requires<[In64BitMode]>;
>> +
>> +
>>
>> //===----------------------------------------------------------------------===//
>> // EH Pseudo Instructions
>> //
>>
>> Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.td?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86InstrInfo.td (original)
>> +++ llvm/trunk/lib/Target/X86/X86InstrInfo.td Tue May 17 15:13:29 2016
>> @@ -112,6 +112,8 @@ def SDT_X86TLSBASEADDR : SDTypeProfile<0
>>
>> def SDT_X86TLSCALL : SDTypeProfile<0, 1, [SDTCisInt<0>]>;
>>
>> +def SDT_X86WIN_ALLOCA : SDTypeProfile<0, 1, [SDTCisVT<0, iPTR>]>;
>> +
>> def SDT_X86SEG_ALLOCA : SDTypeProfile<1, 1, [SDTCisVT<0, iPTR>,
>> SDTCisVT<1, iPTR>]>;
>>
>> def SDT_X86EHRET : SDTypeProfile<0, 1, [SDTCisInt<0>]>;
>> @@ -273,8 +275,8 @@ def X86bextr : SDNode<"X86ISD::BEXTR",
>>
>> def X86mul_imm : SDNode<"X86ISD::MUL_IMM", SDTIntBinOp>;
>>
>> -def X86WinAlloca : SDNode<"X86ISD::WIN_ALLOCA", SDTX86Void,
>> - [SDNPHasChain, SDNPInGlue, SDNPOutGlue]>;
>> +def X86WinAlloca : SDNode<"X86ISD::WIN_ALLOCA", SDT_X86WIN_ALLOCA,
>> + [SDNPHasChain, SDNPOutGlue]>;
>>
>> def X86SegAlloca : SDNode<"X86ISD::SEG_ALLOCA", SDT_X86SEG_ALLOCA,
>> [SDNPHasChain]>;
>>
>> Modified: llvm/trunk/lib/Target/X86/X86MachineFunctionInfo.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86MachineFunctionInfo.h?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86MachineFunctionInfo.h (original)
>> +++ llvm/trunk/lib/Target/X86/X86MachineFunctionInfo.h Tue May 17 15:13:29
>> 2016
>> @@ -98,6 +98,9 @@ class X86MachineFunctionInfo : public Ma
>> /// True if this function uses the red zone.
>> bool UsesRedZone = false;
>>
>> + /// True if this function has WIN_ALLOCA instructions.
>> + bool HasWinAlloca = false;
>> +
>> private:
>> /// ForwardedMustTailRegParms - A list of virtual and physical
>> registers
>> /// that must be forwarded to every musttail call.
>> @@ -172,6 +175,9 @@ public:
>>
>> bool getUsesRedZone() const { return UsesRedZone; }
>> void setUsesRedZone(bool V) { UsesRedZone = V; }
>> +
>> + bool hasWinAlloca() const { return HasWinAlloca; }
>> + void setHasWinAlloca(bool v) { HasWinAlloca = v; }
>> };
>>
>> } // End llvm namespace
>>
>> Modified: llvm/trunk/lib/Target/X86/X86TargetMachine.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86TargetMachine.cpp?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86TargetMachine.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86TargetMachine.cpp Tue May 17 15:13:29
>> 2016
>> @@ -266,6 +266,7 @@ void X86PassConfig::addPreRegAlloc() {
>> addPass(createX86OptimizeLEAs());
>>
>> addPass(createX86CallFrameOptimization());
>> + addPass(createX86WinAllocaExpander());
>> }
>>
>> void X86PassConfig::addPostRegAlloc() {
>>
>> Added: llvm/trunk/lib/Target/X86/X86WinAllocaExpander.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86WinAllocaExpander.cpp?rev=269828&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86WinAllocaExpander.cpp (added)
>> +++ llvm/trunk/lib/Target/X86/X86WinAllocaExpander.cpp Tue May 17 15:13:29
>> 2016
>> @@ -0,0 +1,294 @@
>> +//===----- X86WinAllocaExpander.cpp - Expand WinAlloca pseudo instruction
>> -===//
>> +//
>> +// The LLVM Compiler Infrastructure
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>>
>> +//===----------------------------------------------------------------------===//
>> +//
>> +// This file defines a pass that expands WinAlloca pseudo-instructions.
>> +//
>> +// It performs a conservative analysis to determine whether each
>> allocation
>> +// falls within a region of the stack that is safe to use, or whether
>> stack
>> +// probes must be emitted.
>> +//
>>
>> +//===----------------------------------------------------------------------===//
>> +
>> +#include "X86.h"
>> +#include "X86InstrBuilder.h"
>> +#include "X86InstrInfo.h"
>> +#include "X86MachineFunctionInfo.h"
>> +#include "X86Subtarget.h"
>> +#include "llvm/ADT/PostOrderIterator.h"
>> +#include "llvm/CodeGen/MachineFunctionPass.h"
>> +#include "llvm/CodeGen/MachineInstrBuilder.h"
>> +#include "llvm/CodeGen/MachineRegisterInfo.h"
>> +#include "llvm/CodeGen/Passes.h"
>> +#include "llvm/IR/Function.h"
>> +#include "llvm/Support/raw_ostream.h"
>> +#include "llvm/Target/TargetInstrInfo.h"
>> +
>> +using namespace llvm;
>> +
>> +namespace {
>> +
>> +class X86WinAllocaExpander : public MachineFunctionPass {
>> +public:
>> + X86WinAllocaExpander() : MachineFunctionPass(ID) {}
>> +
>> + bool runOnMachineFunction(MachineFunction &MF) override;
>> +
>> +private:
>> + /// Strategies for lowering a WinAlloca.
>> + enum Lowering { TouchAndSub, Sub, Probe };
>> +
>> + /// Deterministic-order map from WinAlloca instruction to desired
>> lowering.
>> + typedef MapVector<MachineInstr*, Lowering> LoweringMap;
>> +
>> + /// Compute which lowering to use for each WinAlloca instruction.
>> + void computeLowerings(MachineFunction &MF, LoweringMap& Lowerings);
>> +
>> + /// Get the appropriate lowering based on current offset and amount.
>> + Lowering getLowering(int64_t CurrentOffset, int64_t AllocaAmount);
>> +
>> + /// Lower a WinAlloca instruction.
>> + void lower(MachineInstr* MI, Lowering L);
>> +
>> + MachineRegisterInfo *MRI;
>> + const X86Subtarget *STI;
>> + const TargetInstrInfo *TII;
>> + const X86RegisterInfo *TRI;
>> + unsigned StackPtr;
>> + unsigned SlotSize;
>> + int64_t StackProbeSize;
>> +
>> + const char *getPassName() const override { return "X86 WinAlloca
>> Expander"; }
>> + static char ID;
>> +};
>> +
>> +char X86WinAllocaExpander::ID = 0;
>> +
>> +} // end anonymous namespace
>> +
>> +FunctionPass *llvm::createX86WinAllocaExpander() {
>> + return new X86WinAllocaExpander();
>> +}
>> +
>> +/// Return the allocation amount for a WinAlloca instruction, or -1 if
>> unknown.
>> +static int64_t getWinAllocaAmount(MachineInstr *MI, MachineRegisterInfo
>> *MRI) {
>> + assert(MI->getOpcode() == X86::WIN_ALLOCA_32 ||
>> + MI->getOpcode() == X86::WIN_ALLOCA_64);
>> + assert(MI->getOperand(0).isReg());
>> +
>> + unsigned AmountReg = MI->getOperand(0).getReg();
>> + MachineInstr *Def = MRI->getUniqueVRegDef(AmountReg);
>> +
>> + // Look through copies.
>> + while (Def && Def->isCopy() && Def->getOperand(1).isReg())
>> + Def = MRI->getUniqueVRegDef(Def->getOperand(1).getReg());
>> +
>> + if (!Def ||
>> + (Def->getOpcode() != X86::MOV32ri && Def->getOpcode() !=
>> X86::MOV64ri) ||
>> + !Def->getOperand(1).isImm())
>> + return -1;
>> +
>> + return Def->getOperand(1).getImm();
>> +}
>> +
>> +X86WinAllocaExpander::Lowering
>> +X86WinAllocaExpander::getLowering(int64_t CurrentOffset,
>> + int64_t AllocaAmount) {
>> + // For a non-constant amount or a large amount, we have to probe.
>> + if (AllocaAmount < 0 || AllocaAmount > StackProbeSize)
>> + return Probe;
>> +
>> + // If it fits within the safe region of the stack, just subtract.
>> + if (CurrentOffset + AllocaAmount <= StackProbeSize)
>> + return Sub;
>> +
>> + // Otherwise, touch the current tip of the stack, then subtract.
>> + return TouchAndSub;
>> +}
>> +
>> +static bool isPushPop(const MachineInstr &MI) {
>> + switch (MI.getOpcode()) {
>> + case X86::PUSH32i8:
>> + case X86::PUSH32r:
>> + case X86::PUSH32rmm:
>> + case X86::PUSH32rmr:
>> + case X86::PUSHi32:
>> + case X86::PUSH64i8:
>> + case X86::PUSH64r:
>> + case X86::PUSH64rmm:
>> + case X86::PUSH64rmr:
>> + case X86::PUSH64i32:
>> + case X86::POP32r:
>> + case X86::POP64r:
>> + return true;
>> + default:
>> + return false;
>> + }
>> +}
>> +
>> +void X86WinAllocaExpander::computeLowerings(MachineFunction &MF,
>> + LoweringMap &Lowerings) {
>> + // Do a one-pass reverse post-order walk of the CFG to conservatively
>> estimate
>> + // the offset between the stack pointer and the lowest touched part of
>> the
>> + // stack, and use that to decide how to lower each WinAlloca
>> instruction.
>> +
>> + // Initialize OutOffset[B], the stack offset at exit from B, to
>> something big.
>> + DenseMap<MachineBasicBlock *, int64_t> OutOffset;
>> + for (MachineBasicBlock &MBB : MF)
>> + OutOffset[&MBB] = INT32_MAX;
>> +
>> + // Note: we don't know the offset at the start of the entry block since
>> the
>> + // prologue hasn't been inserted yet, and how much that will adjust the
>> stack
>> + // pointer depends on register spills, which have not been computed
>> yet.
>> +
>> + // Compute the reverse post-order.
>> + ReversePostOrderTraversal<MachineFunction*> RPO(&MF);
>> +
>> + for (MachineBasicBlock *MBB : RPO) {
>> + int64_t Offset = -1;
>> + for (MachineBasicBlock *Pred : MBB->predecessors())
>> + Offset = std::max(Offset, OutOffset[Pred]);
>> + if (Offset == -1) Offset = INT32_MAX;
>> +
>> + for (MachineInstr &MI : *MBB) {
>> + if (MI.getOpcode() == X86::WIN_ALLOCA_32 ||
>> + MI.getOpcode() == X86::WIN_ALLOCA_64) {
>> + // A WinAlloca moves StackPtr, and potentially touches it.
>> + int64_t Amount = getWinAllocaAmount(&MI, MRI);
>> + Lowering L = getLowering(Offset, Amount);
>> + Lowerings[&MI] = L;
>> + switch (L) {
>> + case Sub:
>> + Offset += Amount;
>> + break;
>> + case TouchAndSub:
>> + Offset = Amount;
>> + break;
>> + case Probe:
>> + Offset = 0;
>> + break;
>> + }
>> + } else if (MI.isCall() || isPushPop(MI)) {
>> + // Calls, pushes and pops touch the tip of the stack.
>> + Offset = 0;
>> + } else if (MI.getOpcode() == X86::ADJCALLSTACKUP32 ||
>> + MI.getOpcode() == X86::ADJCALLSTACKUP64) {
>> + Offset -= MI.getOperand(0).getImm();
>> + } else if (MI.getOpcode() == X86::ADJCALLSTACKDOWN32 ||
>> + MI.getOpcode() == X86::ADJCALLSTACKDOWN64) {
>> + Offset += MI.getOperand(0).getImm();
>> + } else if (MI.modifiesRegister(StackPtr, TRI)) {
>> + // Any other modification of SP means we've lost track of it.
>> + Offset = INT32_MAX;
>> + }
>> + }
>> +
>> + OutOffset[MBB] = Offset;
>> + }
>> +}
>> +
>> +static unsigned getSubOpcode(bool Is64Bit, int64_t Amount) {
>> + if (Is64Bit)
>> + return isInt<8>(Amount) ? X86::SUB64ri8 : X86::SUB64ri32;
>> + return isInt<8>(Amount) ? X86::SUB32ri8 : X86::SUB32ri;
>> +}
>> +
>> +void X86WinAllocaExpander::lower(MachineInstr* MI, Lowering L) {
>> + DebugLoc DL = MI->getDebugLoc();
>> + MachineBasicBlock *MBB = MI->getParent();
>> + MachineBasicBlock::iterator I = *MI;
>> +
>> + int64_t Amount = getWinAllocaAmount(MI, MRI);
>> + if (Amount == 0) {
>> + MI->eraseFromParent();
>> + return;
>> + }
>> +
>> + bool Is64Bit = STI->is64Bit();
>> + assert(SlotSize == 4 || SlotSize == 8);
>> + unsigned RegA = (SlotSize == 8) ? X86::RAX : X86::EAX;
>> +
>> + switch (L) {
>> + case TouchAndSub:
>> + assert(Amount >= SlotSize);
>> +
>> + // Use a push to touch the top of the stack.
>> + BuildMI(*MBB, I, DL, TII->get(Is64Bit ? X86::PUSH64r : X86::PUSH32r))
>> + .addReg(RegA, RegState::Undef);
>> + Amount -= SlotSize;
>> + if (!Amount)
>> + break;
>> +
>> + // Fall through to make any remaining adjustment.
>> + case Sub:
>> + assert(Amount > 0);
>> + if (Amount == SlotSize) {
>> + // Use push to save size.
>> + BuildMI(*MBB, I, DL, TII->get(Is64Bit ? X86::PUSH64r :
>> X86::PUSH32r))
>> + .addReg(RegA, RegState::Undef);
>> + } else {
>> + // Sub.
>> + BuildMI(*MBB, I, DL, TII->get(getSubOpcode(Is64Bit, Amount)),
>> StackPtr)
>> + .addReg(StackPtr)
>> + .addImm(Amount);
>> + }
>> + break;
>> + case Probe:
>> + // The probe lowering expects the amount in RAX/EAX.
>> + BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::COPY), RegA)
>> + .addReg(MI->getOperand(0).getReg());
>> +
>> + // Do the probe.
>> + STI->getFrameLowering()->emitStackProbe(*MBB->getParent(), *MBB, MI,
>> DL,
>> + /*InPrologue=*/false);
>> + break;
>> + }
>> +
>> + unsigned AmountReg = MI->getOperand(0).getReg();
>> + MI->eraseFromParent();
>> +
>> + // Delete the definition of AmountReg, possibly walking a chain of
>> copies.
>> + for (;;) {
>> + if (!MRI->use_empty(AmountReg))
>> + break;
>> + MachineInstr *AmountDef = MRI->getUniqueVRegDef(AmountReg);
>> + if (!AmountDef)
>> + break;
>> + if (AmountDef->isCopy() && AmountDef->getOperand(1).isReg())
>> + AmountReg = AmountDef->getOperand(1).isReg();
>> + AmountDef->eraseFromParent();
>> + break;
>> + }
>> +}
>> +
>> +bool X86WinAllocaExpander::runOnMachineFunction(MachineFunction &MF) {
>> + if (!MF.getInfo<X86MachineFunctionInfo>()->hasWinAlloca())
>> + return false;
>> +
>> + MRI = &MF.getRegInfo();
>> + STI = &MF.getSubtarget<X86Subtarget>();
>> + TII = STI->getInstrInfo();
>> + TRI = STI->getRegisterInfo();
>> + StackPtr = TRI->getStackRegister();
>> + SlotSize = TRI->getSlotSize();
>> +
>> + StackProbeSize = 4096;
>> + if (MF.getFunction()->hasFnAttribute("stack-probe-size")) {
>> + MF.getFunction()
>> + ->getFnAttribute("stack-probe-size")
>> + .getValueAsString()
>> + .getAsInteger(0, StackProbeSize);
>> + }
>> +
>> + LoweringMap Lowerings;
>> + computeLowerings(MF, Lowerings);
>> + for (auto &P : Lowerings)
>> + lower(P.first, P.second);
>> +
>> + return true;
>> +}
>>
>> Modified: llvm/trunk/test/CodeGen/X86/cleanuppad-inalloca.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/cleanuppad-inalloca.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/cleanuppad-inalloca.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/cleanuppad-inalloca.ll Tue May 17 15:13:29
>> 2016
>> @@ -38,8 +38,8 @@ ehcleanup:
>> ; CHECK: pushl %ebp
>> ; CHECK: movl %esp, %ebp
>> ; CHECK: subl ${{[0-9]+}}, %esp
>> -; CHECK: movl $8, %eax
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: pushl %eax
>> ; CHECK: calll "??0A@@QAE at XZ"
>> ; CHECK: calll "??0A@@QAE at XZ"
>> ; CHECK: calll _takes_two
>>
>> Modified: llvm/trunk/test/CodeGen/X86/dynamic-alloca-in-entry.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/dynamic-alloca-in-entry.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/dynamic-alloca-in-entry.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/dynamic-alloca-in-entry.ll Tue May 17
>> 15:13:29 2016
>> @@ -15,5 +15,5 @@ define void @bar() {
>> ret void
>> }
>> ; CHECK-LABEL: _bar:
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> ; CHECK: retl
>>
>> Modified: llvm/trunk/test/CodeGen/X86/inalloca-ctor.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/inalloca-ctor.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/inalloca-ctor.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/inalloca-ctor.ll Tue May 17 15:13:29 2016
>> @@ -12,8 +12,8 @@ define void @g() {
>> entry:
>> %args = alloca inalloca %frame
>> %c = getelementptr %frame, %frame* %args, i32 0, i32 2
>> -; CHECK: movl $20, %eax
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: subl $16, %esp
>> ; CHECK: movl %esp,
>> call void @Foo_ctor(%Foo* %c)
>> ; CHECK: leal 12(%{{.*}}),
>>
>> Modified: llvm/trunk/test/CodeGen/X86/inalloca-invoke.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/inalloca-invoke.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/inalloca-invoke.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/inalloca-invoke.ll Tue May 17 15:13:29
>> 2016
>> @@ -21,7 +21,8 @@ blah:
>> %beg = getelementptr %frame.reverse, %frame.reverse* %rev_args, i32 0,
>> i32 0
>> %end = getelementptr %frame.reverse, %frame.reverse* %rev_args, i32 0,
>> i32 1
>>
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: subl $20, %esp
>> ; CHECK: movl %esp, %[[beg:[^ ]*]]
>> ; CHECK: leal 12(%[[beg]]), %[[end:[^ ]*]]
>>
>>
>> Modified: llvm/trunk/test/CodeGen/X86/inalloca-stdcall.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/inalloca-stdcall.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/inalloca-stdcall.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/inalloca-stdcall.ll Tue May 17 15:13:29
>> 2016
>> @@ -8,8 +8,8 @@ declare x86_stdcallcc void @i(i32 %a)
>> define void @g() {
>> ; CHECK-LABEL: _g:
>> %b = alloca inalloca %Foo
>> -; CHECK: movl $8, %eax
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: pushl %eax
>> %f1 = getelementptr %Foo, %Foo* %b, i32 0, i32 0
>> %f2 = getelementptr %Foo, %Foo* %b, i32 0, i32 1
>> store i32 13, i32* %f1
>>
>> Modified: llvm/trunk/test/CodeGen/X86/inalloca.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/inalloca.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/inalloca.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/inalloca.ll Tue May 17 15:13:29 2016
>> @@ -8,8 +8,8 @@ define void @a() {
>> ; CHECK-LABEL: _a:
>> entry:
>> %b = alloca inalloca %Foo
>> -; CHECK: movl $8, %eax
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: pushl %eax
>> %f1 = getelementptr %Foo, %Foo* %b, i32 0, i32 0
>> %f2 = getelementptr %Foo, %Foo* %b, i32 0, i32 1
>> store i32 13, i32* %f1
>> @@ -28,8 +28,8 @@ define void @b() {
>> ; CHECK-LABEL: _b:
>> entry:
>> %b = alloca inalloca %Foo
>> -; CHECK: movl $8, %eax
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: pushl %eax
>> %f1 = getelementptr %Foo, %Foo* %b, i32 0, i32 0
>> %f2 = getelementptr %Foo, %Foo* %b, i32 0, i32 1
>> store i32 13, i32* %f1
>> @@ -49,8 +49,8 @@ define void @c() {
>> ; CHECK-LABEL: _c:
>> entry:
>> %b = alloca inalloca %Foo
>> -; CHECK: movl $8, %eax
>> -; CHECK: calll __chkstk
>> +; CHECK: pushl %eax
>> +; CHECK: pushl %eax
>> %f1 = getelementptr %Foo, %Foo* %b, i32 0, i32 0
>> %f2 = getelementptr %Foo, %Foo* %b, i32 0, i32 1
>> store i32 13, i32* %f1
>>
>> Modified: llvm/trunk/test/CodeGen/X86/shrink-wrap-chkstk.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/shrink-wrap-chkstk.ll?rev=269828&r1=269827&r2=269828&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/shrink-wrap-chkstk.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/shrink-wrap-chkstk.ll Tue May 17 15:13:29
>> 2016
>> @@ -7,7 +7,7 @@
>> target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
>> target triple = "i686-pc-windows-msvc18.0.0"
>>
>> -%struct.S = type { [12 x i8] }
>> +%struct.S = type { [8192 x i8] }
>>
>> define x86_thiscallcc void @call_inalloca(i1 %x) {
>> entry:
>> @@ -29,7 +29,7 @@ bb2:
>> ; CHECK-LABEL: _call_inalloca: # @call_inalloca
>> ; CHECK: pushl %ebp
>> ; CHECK: movl %esp, %ebp
>> -; CHECK: movl $12, %eax
>> +; CHECK: movl $8192, %eax
>> ; CHECK: calll __chkstk
>> ; CHECK: calll _inalloca_params
>> ; CHECK: movl %ebp, %esp
>>
>> Added: llvm/trunk/test/CodeGen/X86/win-alloca-expander.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/win-alloca-expander.ll?rev=269828&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/win-alloca-expander.ll (added)
>> +++ llvm/trunk/test/CodeGen/X86/win-alloca-expander.ll Tue May 17 15:13:29
>> 2016
>> @@ -0,0 +1,153 @@
>> +; RUN: llc < %s -mtriple=i686-pc-win32 | FileCheck %s
>> +
>> +%struct.S = type { [1024 x i8] }
>> +%struct.T = type { [3000 x i8] }
>> +%struct.U = type { [10000 x i8] }
>> +
>> +define void @basics() {
>> +; CHECK-LABEL: basics:
>> +entry:
>> + br label %bb1
>> +
>> +; Allocation move sizes should have been removed.
>> +; CHECK-NOT: movl $1024
>> +; CHECK-NOT: movl $3000
>> +
>> +bb1:
>> + %p0 = alloca %struct.S
>> +; The allocation is small enough not to require stack probing, but the
>> %esp
>> +; offset after the prologue is not known, so the stack must be touched
>> before
>> +; the pointer is adjusted.
>> +; CHECK: pushl %eax
>> +; CHECK: subl $1020, %esp
>> +
>> + %saved_stack = tail call i8* @llvm.stacksave()
>> +
>> + %p1 = alloca %struct.S
>> +; We know the %esp offset from above, so there is no need to touch the
>> stack
>> +; before adjusting it.
>> +; CHECK: subl $1024, %esp
>> +
>> + %p2 = alloca %struct.T
>> +; The offset is now 2048 bytes, so allocating a T must touch the stack
>> again.
>> +; CHECK: pushl %eax
>> +; CHECK: subl $2996, %esp
>> +
>> + call void @f(%struct.S* %p0)
>> +; CHECK: calll
>> +
>> + %p3 = alloca %struct.T
>> +; The call above touched the stack, so there is room for a T object.
>> +; CHECK: subl $3000, %esp
>> +
>> + %p4 = alloca %struct.U
>> +; The U object is large enough to require stack probing.
>> +; CHECK: movl $10000, %eax
>> +; CHECK: calll __chkstk
>> +
>> + %p5 = alloca %struct.T
>> +; The stack probing above touched the tip of the stack, so there's room
>> for a T.
>> +; CHECK: subl $3000, %esp
>> +
>> + call void @llvm.stackrestore(i8* %saved_stack)
>> + %p6 = alloca %struct.S
>> +; The stack restore means we lose track of the stack pointer and must
>> probe.
>> +; CHECK: pushl %eax
>> +; CHECK: subl $1020, %esp
>> +
>> +; Use the pointers so they're not optimized away.
>> + call void @f(%struct.S* %p1)
>> + call void @g(%struct.T* %p2)
>> + call void @g(%struct.T* %p3)
>> + call void @h(%struct.U* %p4)
>> + call void @g(%struct.T* %p5)
>> + ret void
>> +}
>> +
>> +define void @loop() {
>> +; CHECK-LABEL: loop:
>> +entry:
>> + br label %bb1
>> +
>> +bb1:
>> + %p1 = alloca %struct.S
>> +; The entry offset is unknown; touch-and-sub.
>> +; CHECK: pushl %eax
>> +; CHECK: subl $1020, %esp
>> + br label %loop1
>> +
>> +loop1:
>> + %i1 = phi i32 [ 10, %bb1 ], [ %dec1, %loop1 ]
>> + %p2 = alloca %struct.S
>> +; We know the incoming offset from bb1, but from the back-edge, we assume
>> the
>> +; worst, and therefore touch-and-sub to allocate.
>> +; CHECK: pushl %eax
>> +; CHECK: subl $1020, %esp
>> + %dec1 = sub i32 %i1, 1
>> + %cmp1 = icmp sgt i32 %i1, 0
>> + br i1 %cmp1, label %loop1, label %end
>> +; CHECK: decl
>> +; CHECK: jg
>> +
>> +end:
>> + call void @f(%struct.S* %p1)
>> + call void @f(%struct.S* %p2)
>> + ret void
>> +}
>> +
>> +define void @probe_size_attribute() "stack-probe-size"="512" {
>> +; CHECK-LABEL: probe_size_attribute:
>> +entry:
>> + br label %bb1
>> +
>> +bb1:
>> + %p0 = alloca %struct.S
>> +; The allocation would be small enough not to require probing, if it
>> wasn't
>> +; for the stack-probe-size attribute.
>> +; CHECK: movl $1024, %eax
>> +; CHECK: calll __chkstk
>> + call void @f(%struct.S* %p0)
>> + ret void
>> +}
>> +
>> +define void @cfg(i1 %x, i1 %y) {
>> +; Test that the blocks are analyzed in the correct order.
>> +; CHECK-LABEL: cfg:
>> +entry:
>> + br i1 %x, label %bb1, label %bb2
>> +
>> +bb1:
>> + %p1 = alloca %struct.S
>> +; CHECK: pushl %eax
>> +; CHECK: subl $1020, %esp
>> + br label %bb3
>> +bb2:
>> + %p2 = alloca %struct.T
>> +; CHECK: pushl %eax
>> +; CHECK: subl $2996, %esp
>> + br label %bb3
>> +
>> +bb3:
>> + br i1 %y, label %bb4, label %bb5
>> +
>> +bb4:
>> + %p4 = alloca %struct.S
>> +; CHECK: subl $1024, %esp
>> + call void @f(%struct.S* %p4)
>> + ret void
>> +
>> +bb5:
>> + %p5 = alloca %struct.T
>> +; CHECK: pushl %eax
>> +; CHECK: subl $2996, %esp
>> + call void @g(%struct.T* %p5)
>> + ret void
>> +}
>> +
>> +
>> +declare void @f(%struct.S*)
>> +declare void @g(%struct.T*)
>> +declare void @h(%struct.U*)
>> +
>> +declare i8* @llvm.stacksave()
>> +declare void @llvm.stackrestore(i8*)
>>
>>
>> _______________________________________________
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>> llvm-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
> --
> Mike
> Sent from phone
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