Target/X86: [PR8777][PR8778] Tweak alloca/chkstk for Windows targets.
FIXME: Some cleanups would be needed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128206 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp
index 3246c43..071fbe0 100644
--- a/lib/Target/X86/X86FrameLowering.cpp
+++ b/lib/Target/X86/X86FrameLowering.cpp
@@ -551,60 +551,66 @@
// 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 &&
- (STI.isTargetCygMing() || STI.isTargetWin32()) &&
- !STI.isTargetEnvMacho()) {
+ if (NumBytes >= 4096 && STI.isTargetCOFF() && !STI.isTargetEnvMacho()) {
+ const char *StackProbeSymbol;
+ bool isSPUpdateNeeded = false;
+
+ if (Is64Bit) {
+ if (STI.isTargetCygMing())
+ StackProbeSymbol = "___chkstk";
+ else {
+ StackProbeSymbol = "__chkstk";
+ isSPUpdateNeeded = true;
+ }
+ } else if (STI.isTargetCygMing())
+ StackProbeSymbol = "_alloca";
+ else
+ StackProbeSymbol = "_chkstk";
+
// Check whether EAX is livein for this function.
bool isEAXAlive = isEAXLiveIn(MF);
- const char *StackProbeSymbol =
- STI.isTargetWindows() ? "_chkstk" : "_alloca";
- if (Is64Bit && STI.isTargetCygMing())
- StackProbeSymbol = "__chkstk";
- unsigned CallOp = Is64Bit ? X86::CALL64pcrel32 : X86::CALLpcrel32;
- if (!isEAXAlive) {
- BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
- .addImm(NumBytes);
- BuildMI(MBB, MBBI, DL, TII.get(CallOp))
- .addExternalSymbol(StackProbeSymbol)
- .addReg(StackPtr, RegState::Define | RegState::Implicit)
- .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
- } else {
+ if (isEAXAlive) {
+ // Sanity check that EAX is not livein for this function.
+ // It should not be, so throw an assert.
+ assert(!Is64Bit && "EAX is livein in x64 case!");
+
// Save EAX
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r))
.addReg(X86::EAX, RegState::Kill);
-
- // Allocate NumBytes-4 bytes on stack. We'll also use 4 already
- // allocated bytes for EAX.
- BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
- .addImm(NumBytes - 4);
- BuildMI(MBB, MBBI, DL, TII.get(CallOp))
- .addExternalSymbol(StackProbeSymbol)
- .addReg(StackPtr, RegState::Define | RegState::Implicit)
- .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
-
- // Restore EAX
- MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm),
- X86::EAX),
- StackPtr, false, NumBytes - 4);
- MBB.insert(MBBI, MI);
}
- } else if (NumBytes >= 4096 &&
- STI.isTargetWin64() &&
- !STI.isTargetEnvMacho()) {
- // Sanity check that EAX is not livein for this function. It should
- // not be, so throw an assert.
- assert(!isEAXLiveIn(MF) && "EAX is livein in the Win64 case!");
- // Handle the 64-bit Windows ABI case where we need to call __chkstk.
- // Function prologue is responsible for adjusting the stack pointer.
- BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
- .addImm(NumBytes);
- BuildMI(MBB, MBBI, DL, TII.get(X86::WINCALL64pcrel32))
- .addExternalSymbol("__chkstk")
- .addReg(StackPtr, RegState::Define | RegState::Implicit);
- emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit,
- TII, *RegInfo);
+ if (Is64Bit) {
+ // Handle the 64-bit Windows ABI case where we need to call __chkstk.
+ // Function prologue is responsible for adjusting the stack pointer.
+ BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::RAX)
+ .addImm(NumBytes);
+ } else {
+ // Allocate NumBytes-4 bytes on stack in case of isEAXAlive.
+ // We'll also use 4 already allocated bytes for EAX.
+ BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
+ .addImm(isEAXAlive ? NumBytes - 4 : NumBytes);
+ }
+
+ BuildMI(MBB, MBBI, DL,
+ TII.get(Is64Bit ? X86::W64ALLOCA : X86::CALLpcrel32))
+ .addExternalSymbol(StackProbeSymbol)
+ .addReg(StackPtr, RegState::Define | RegState::Implicit)
+ .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
+
+ // MSVC x64's __chkstk needs to adjust %rsp.
+ // FIXME: %rax preserves the offset and should be available.
+ if (isSPUpdateNeeded)
+ emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit,
+ TII, *RegInfo);
+
+ if (isEAXAlive) {
+ // Restore EAX
+ MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm),
+ X86::EAX),
+ StackPtr, false, NumBytes - 4);
+ MBB.insert(MBBI, MI);
+ }
} else if (NumBytes)
emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit,
TII, *RegInfo);