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[X86] Handle EAX being live when calling chkstk for x86_64

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EAX can turn out to be alive here, when shrink wrapping is done
(which is allowed when using dwarf exceptions, contrary to the
normal case with WinCFI).

This fixes PR36487.

Differential Revision: https://reviews.llvm.org/D43968

llvm-svn: 326764
This commit is contained in:
Martin Storsjo 2018-03-06 06:00:13 +00:00
parent b87e2d495b
commit 37c24a1860
2 changed files with 61 additions and 17 deletions
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42
lib/Target/X86/X86FrameLowering.cpp
View File

@ -1213,30 +1213,34 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
bool isEAXAlive = isEAXLiveIn(MBB);
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)
.setMIFlag(MachineInstr::FrameSetup);
if (Is64Bit) {
// Save RAX
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH64r))
.addReg(X86::RAX, RegState::Kill)
.setMIFlag(MachineInstr::FrameSetup);
} else {
// Save EAX
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r))
.addReg(X86::EAX, RegState::Kill)
.setMIFlag(MachineInstr::FrameSetup);
}
}
if (Is64Bit) {
// Handle the 64-bit Windows ABI case where we need to call __chkstk.
// Function prologue is responsible for adjusting the stack pointer.
if (isUInt<32>(NumBytes)) {
int Alloc = isEAXAlive ? NumBytes - 8 : NumBytes;
if (isUInt<32>(Alloc)) {
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
.addImm(NumBytes)
.addImm(Alloc)
.setMIFlag(MachineInstr::FrameSetup);
} else if (isInt<32>(NumBytes)) {
} else if (isInt<32>(Alloc)) {
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri32), X86::RAX)
.addImm(NumBytes)
.addImm(Alloc)
.setMIFlag(MachineInstr::FrameSetup);
} else {
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::RAX)
.addImm(NumBytes)
.addImm(Alloc)
.setMIFlag(MachineInstr::FrameSetup);
}
} else {
@ -1251,10 +1255,14 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
emitStackProbe(MF, MBB, MBBI, DL, true);
if (isEAXAlive) {
// Restore EAX
MachineInstr *MI =
addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), X86::EAX),
StackPtr, false, NumBytes - 4);
// Restore RAX/EAX
MachineInstr *MI;
if (Is64Bit)
MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV64rm), X86::RAX),
StackPtr, false, NumBytes - 8);
else
MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), X86::EAX),
StackPtr, false, NumBytes - 4);
MI->setFlag(MachineInstr::FrameSetup);
MBB.insert(MBBI, MI);
}

36
test/CodeGen/X86/shrink-wrap-chkstk-x86_64.ll Normal file
View File

@ -0,0 +1,36 @@
; RUN: llc -mtriple=x86_64-windows-gnu -exception-model=dwarf < %s | FileCheck %s
%struct.A = type { [4096 x i8] }
@a = common global i32 0, align 4
@b = common global i32 0, align 4
define void @fn1() nounwind uwtable {
entry:
%ctx = alloca %struct.A, align 1
%0 = load i32, i32* @a, align 4
%tobool = icmp eq i32 %0, 0
%div = sdiv i32 %0, 6
%cond = select i1 %tobool, i32 %div, i32 %0
store i32 %cond, i32* @b, align 4
%1 = getelementptr inbounds %struct.A, %struct.A* %ctx, i64 0, i32 0, i64 0
call void @llvm.lifetime.start.p0i8(i64 4096, i8* nonnull %1)
%2 = ptrtoint %struct.A* %ctx to i64
%3 = trunc i64 %2 to i32
call void @fn2(i32 %3)
call void @llvm.lifetime.end.p0i8(i64 4096, i8* nonnull %1)
ret void
}
declare void @fn2(i32)
declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
; CHECK-LABEL: fn1:
; CHECK: pushq %rax
; CHECK: movl $4128, %eax
; CHECK: callq ___chkstk_ms
; CHECK: subq %rax, %rsp
; CHECK: movq 4128(%rsp), %rax
; CHECK: addq $4136, %rsp