Commit 943513b7 authored by Martin Storsjö's avatar Martin Storsjö
Browse files

[X86] [Win64] Avoid truncating large (> 32 bit) stack allocations 

This fixes PR44129, which was broken in a7adc318 (in 7.0.0
and newer).

Differential Revision: https://reviews.llvm.org/D70741
parent 344bdeb7

llvm/lib/Target/X86/X86FrameLowering.cpp

+1 −1
Original line number Diff line number Diff line
@@ -1261,7 +1261,7 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF, 
    if (Is64Bit) {

      // Handle the 64-bit Windows ABI case where we need to call __chkstk.

      // Function prologue is responsible for adjusting the stack pointer.

      int Alloc = isEAXAlive ? NumBytes - 8 : NumBytes;

      int64_t Alloc = isEAXAlive ? NumBytes - 8 : NumBytes;

      if (isUInt<32>(Alloc)) {

        BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)

            .addImm(Alloc)

llvm/test/CodeGen/X86/win64-stackprobe-overflow.ll

0 → 100644
+14 −0
Original line number Diff line number Diff line 
; RUN: llc < %s -mtriple=x86_64-windows-gnu | FileCheck %s



define void @foo() unnamed_addr #0 {

start:

  %b = alloca i64, align 8

  %c = alloca [4294967295 x i8], align 1

  ret void

}



attributes #0 = { nonlazybind uwtable "probe-stack"="probe_stack" "target-cpu"="x86-64" }



; CHECK-LABEL: foo:

; CHECK: movabsq $4294967304, %rax

; CHECK-NEXT: callq probe_stack