Commit d1786389 authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r355136: 

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r355136 | efriedma | 2019-02-28 21:38:45 +0100 (Thu, 28 Feb 2019) | 12 lines

[AArch64] [Windows] Don't skip constructing UnwindHelp.

In certain cases, the first non-frame-setup instruction in a function is
a branch.  For example, it could be a cbz on an argument.  Make sure we
correctly allocate the UnwindHelp, and find an appropriate register to
use to initialize it.

Fixes https://bugs.llvm.org/show_bug.cgi?id=40184

Differential Revision: https://reviews.llvm.org/D58752


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llvm-svn: 355313
parent 502c6557

llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

+4 −5
Original line number Diff line number Diff line
@@ -2108,9 +2108,6 @@ void AArch64FrameLowering::processFunctionBeforeFrameFinalized( 
  while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup))

    ++MBBI;



  if (MBBI->isTerminator())

    return;



  // Create an UnwindHelp object.

  int UnwindHelpFI =

      MFI.CreateStackObject(/*size*/8, /*alignment*/16, false);
@@ -2118,8 +2115,10 @@ void AArch64FrameLowering::processFunctionBeforeFrameFinalized( 
  // We need to store -2 into the UnwindHelp object at the start of the

  // function.

  DebugLoc DL;

  RS->enterBasicBlock(MBB);

  unsigned DstReg = RS->scavengeRegister(&AArch64::GPR64RegClass, MBBI, 0);

  RS->enterBasicBlockEnd(MBB);

  RS->backward(std::prev(MBBI));

  unsigned DstReg = RS->FindUnusedReg(&AArch64::GPR64commonRegClass);

  assert(DstReg && "There must be a free register after frame setup");

  BuildMI(MBB, MBBI, DL, TII.get(AArch64::MOVi64imm), DstReg).addImm(-2);

  BuildMI(MBB, MBBI, DL, TII.get(AArch64::STURXi))

      .addReg(DstReg, getKillRegState(true))

llvm/test/CodeGen/AArch64/wineh-try-catch-cbz.ll

0 → 100644
+40 −0
Original line number Diff line number Diff line 
; RUN: llc < %s | FileCheck %s



; Make sure the prologue is sane.  (Doesn't need to exactly match this,

; but the original issue only reproduced if the cbz was immediately

; after the frame setup.)



; CHECK:      sub     sp, sp, #32

; CHECK-NEXT: stp     x29, x30, [sp, #16]

; CHECK-NEXT: add     x29, sp, #16

; CHECK-NEXT: orr     x1, xzr, #0xfffffffffffffffe

; CHECK-NEXT: stur    x1, [x29, #-16]

; CHECK-NEXT: cbz     w0, .LBB0_2



target datalayout = "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128"

target triple = "aarch64-unknown-windows-msvc19.11.0"



; Function Attrs: uwtable

define dso_local void @"?f@@YAXH@Z"(i32 %x) local_unnamed_addr #0 personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {

entry:

  %cmp = icmp eq i32 %x, 0

  br i1 %cmp, label %try.cont, label %if.then



if.then:                                          ; preds = %entry

  invoke void @"?g@@YAXXZ"()

          to label %try.cont unwind label %catch.dispatch



catch.dispatch:                                   ; preds = %if.then

  %0 = catchswitch within none [label %catch] unwind to caller



catch:                                            ; preds = %catch.dispatch

  %1 = catchpad within %0 [i8* null, i32 64, i8* null]

  catchret from %1 to label %try.cont



try.cont:                                         ; preds = %entry, %if.then, %catch

  ret void

}



declare dso_local void @"?g@@YAXXZ"() local_unnamed_addr #1



declare dso_local i32 @__CxxFrameHandler3(...)

llvm/test/CodeGen/AArch64/wineh-try-catch.ll

+2 −2
Original line number Diff line number Diff line
@@ -22,8 +22,8 @@ 
; CHECK:       add     x29, sp, #32

; CHECK:       sub     sp, sp, #624

; CHECK:       mov     x19, sp

; CHECK:       orr     x1, xzr, #0xfffffffffffffffe

; CHECK:       stur    x1, [x19]

; CHECK:       orr     x0, xzr, #0xfffffffffffffffe

; CHECK:       stur    x0, [x19]



; Now check that x is stored at fp - 20.  We check that this is the same

; location accessed from the funclet to retrieve x.