From ace53f2fbc65f1e26c084c733ffbdbe3516580a6 Mon Sep 17 00:00:00 2001 From: Anton Korobeynikov Date: Thu, 2 Sep 2010 23:03:46 +0000 Subject: [PATCH] Properly emit __chkstk call instead of __alloca on non-mingw windows targets. Patch by Cameron Esfahani! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112902 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/X86RegisterInfo.cpp | 25 +++++++++++------ lib/Target/X86/X86Subtarget.h | 4 +++ test/CodeGen/X86/win_chkstk.ll | 45 ++++++++++++++++++++++++++++++ 3 files changed, 66 insertions(+), 8 deletions(-) create mode 100644 test/CodeGen/X86/win_chkstk.ll diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp index 03c7ffc2bc2..fedd49ebb54 100644 --- a/lib/Target/X86/X86RegisterInfo.cpp +++ b/lib/Target/X86/X86RegisterInfo.cpp @@ -764,7 +764,7 @@ void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, } } -/// mergeSPUpdatesUp - Merge two stack-manipulating instructions lower iterator. +/// mergeSPUpdatesDown - Merge two stack-manipulating instructions lower iterator. static void mergeSPUpdatesDown(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, @@ -1087,7 +1087,17 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { DL = MBB.findDebugLoc(MBBI); // Adjust stack pointer: ESP -= numbytes. - if (NumBytes >= 4096 && Subtarget->isTargetCygMing()) { + + // Windows and cygwin/mingw require a prologue helper routine when allocating + // more than 4K bytes on the stack. Windows uses __chkstk and cygwin/mingw + // uses __alloca. __alloca and the 32-bit version of __chkstk will probe + // the stack and adjust the stack pointer in one go. The 64-bit version + // of __chkstk is only responsible for probing the stack. The 64-bit + // prologue is responsible for adjusting the stack pointer. 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. + if (NumBytes >= 4096 && + (Subtarget->isTargetCygMing() || Subtarget->isTargetWin32())) { // Check, whether EAX is livein for this function. bool isEAXAlive = false; for (MachineRegisterInfo::livein_iterator @@ -1098,15 +1108,14 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { Reg == X86::AH || Reg == X86::AL); } - // Function prologue calls _alloca 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. + + const char *StackProbeSymbol = + Subtarget->isTargetWindows() ? "_chkstk" : "_alloca"; if (!isEAXAlive) { BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX) .addImm(NumBytes); BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32)) - .addExternalSymbol("_alloca") + .addExternalSymbol(StackProbeSymbol) .addReg(StackPtr, RegState::Define | RegState::Implicit) .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit); } else { @@ -1119,7 +1128,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX) .addImm(NumBytes - 4); BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32)) - .addExternalSymbol("_alloca") + .addExternalSymbol(StackProbeSymbol) .addReg(StackPtr, RegState::Define | RegState::Implicit) .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit); diff --git a/lib/Target/X86/X86Subtarget.h b/lib/Target/X86/X86Subtarget.h index 531fb04bd60..0ee91abe21f 100644 --- a/lib/Target/X86/X86Subtarget.h +++ b/lib/Target/X86/X86Subtarget.h @@ -186,6 +186,10 @@ public: return Is64Bit && (isTargetMingw() || isTargetWindows()); } + bool isTargetWin32() const { + return !Is64Bit && (isTargetMingw() || isTargetWindows()); + } + std::string getDataLayout() const { const char *p; if (is64Bit()) diff --git a/test/CodeGen/X86/win_chkstk.ll b/test/CodeGen/X86/win_chkstk.ll new file mode 100644 index 00000000000..27d3358d4ac --- /dev/null +++ b/test/CodeGen/X86/win_chkstk.ll @@ -0,0 +1,45 @@ +; RUN: llc < %s -mtriple=i686-pc-win32 | FileCheck %s -check-prefix=WIN_X32 +; RUN: llc < %s -mtriple=i686-pc-mingw32 | FileCheck %s -check-prefix=MINGW_X32 +; RUN: llc < %s -mtriple=x86_64-pc-mingw32 | FileCheck %s -check-prefix=MINGW_X64 +; RUN: llc < %s -mtriple=i386-pc-linux | FileCheck %s -check-prefix=LINUX + +; Windows and mingw require a prologue helper routine if more than 4096 bytes area +; allocated on the stack. Windows uses __chkstk and mingw uses __alloca. __alloca +; and the 32-bit version of __chkstk will probe the stack and adjust the stack pointer. +; The 64-bit version of __chkstk is only responsible for probing the stack. The 64-bit +; prologue is responsible for adjusting the stack pointer. + +; Stack allocation >= 4096 bytes will require call to __chkstk in the Windows ABI. +define i32 @main4k() nounwind { +entry: +; WIN_X32: call __chkstk +; WIN_X64: call __chkstk +; MINGW_X32: call __alloca +; MINGW_X64: call _alloca +; LINUX-NOT: call __chkstk + %array4096 = alloca [4096 x i8], align 16 ; <[4096 x i8]*> [#uses=0] + ret i32 0 +} + +; Make sure we don't call __chkstk or __alloca when we have less than a 4096 stack +; allocation. +define i32 @main128() nounwind { +entry: +; WIN_X32: # BB#0: +; WIN_X32-NOT: call __chkstk +; WIN_X32: ret + +; WIN_X64: # BB#0: +; WIN_X64-NOT: call __chkstk +; WIN_X64: ret + +; MINGW_X64: # BB#0: +; MINGW_X64-NOT: call _alloca +; MINGW_X64: ret + +; LINUX: # BB#0: +; LINUX-NOT: call __chkstk +; LINUX: ret + %array128 = alloca [128 x i8], align 16 ; <[128 x i8]*> [#uses=0] + ret i32 0 +}