Commit 309d5514 authored by Nikita Popov's avatar Nikita Popov Committed by Tobias Hieta
Browse files

[AArch64][GlobalISel] Fix incorrect ABI when tail call not supported (#70215) 

The check for whether a tail call is supported calls
determineAssignments(), which may modify argument flags. As such, even
though the check fails and a non-tail call will be emitted, it will not
have a different (incorrect) ABI.

Fix this by operating on a separate copy of the arguments.

Fixes https://github.com/llvm/llvm-project/issues/70207.

(cherry picked from commit 292f34b0)
parent 9477268e

llvm/lib/Target/AArch64/GISel/AArch64CallLowering.cpp

+5 −2
Original line number Diff line number Diff line
@@ -829,9 +829,9 @@ bool AArch64CallLowering::doCallerAndCalleePassArgsTheSameWay( 


bool AArch64CallLowering::areCalleeOutgoingArgsTailCallable(

    CallLoweringInfo &Info, MachineFunction &MF,

    SmallVectorImpl<ArgInfo> &OutArgs) const {

    SmallVectorImpl<ArgInfo> &OrigOutArgs) const {

  // If there are no outgoing arguments, then we are done.

  if (OutArgs.empty())

  if (OrigOutArgs.empty())

    return true;



  const Function &CallerF = MF.getFunction();
@@ -851,6 +851,9 @@ bool AArch64CallLowering::areCalleeOutgoingArgsTailCallable( 


  AArch64OutgoingValueAssigner CalleeAssigner(AssignFnFixed, AssignFnVarArg,

                                              Subtarget, /*IsReturn*/ false);

  // determineAssignments() may modify argument flags, so make a copy.

  SmallVector<ArgInfo, 8> OutArgs;

  append_range(OutArgs, OrigOutArgs);

  if (!determineAssignments(CalleeAssigner, OutArgs, OutInfo)) {

    LLVM_DEBUG(dbgs() << "... Could not analyze call operands.\n");

    return false;

llvm/test/CodeGen/AArch64/GlobalISel/call-lowering-tail-call-fallback.ll

+7 −11
Original line number Diff line number Diff line
@@ -3,30 +3,26 @@ 


declare void @func(i64, i64, i64, i64, i64, i128, i128)



; FIXME: This is a miscompile.

; Make sure the check for whether a tail call is allowed does not affect the

; calling convention if it fails.

; The first i128 argument should be passed in registers, not on the stack.

define void @pr70207(i128 %arg1, i128 %arg2) nounwind {

; CHECK-LABEL: pr70207:

; CHECK:       // %bb.0:

; CHECK-NEXT:    sub sp, sp, #64

; CHECK-NEXT:    mov x8, x2

; CHECK-NEXT:    mov x6, x0

; CHECK-NEXT:    mov x8, x1

; CHECK-NEXT:    mov x9, x2

; CHECK-NEXT:    mov x10, x3

; CHECK-NEXT:    mov x7, x1

; CHECK-NEXT:    mov x9, x3

; CHECK-NEXT:    mov x0, xzr

; CHECK-NEXT:    mov x1, xzr

; CHECK-NEXT:    mov x2, xzr

; CHECK-NEXT:    mov x3, xzr

; CHECK-NEXT:    mov x4, xzr

; CHECK-NEXT:    str x30, [sp, #48] // 8-byte Folded Spill

; CHECK-NEXT:    str x8, [sp]

; CHECK-NEXT:    str x9, [sp, #16]

; CHECK-NEXT:    str x10, [sp, #32]

; CHECK-NEXT:    str x8, [sp, #-32]!

; CHECK-NEXT:    stp x9, x30, [sp, #8] // 8-byte Folded Spill

; CHECK-NEXT:    bl func

; CHECK-NEXT:    ldr x30, [sp, #48] // 8-byte Folded Reload

; CHECK-NEXT:    add sp, sp, #64

; CHECK-NEXT:    ldr x30, [sp, #16] // 8-byte Folded Reload

; CHECK-NEXT:    add sp, sp, #32

; CHECK-NEXT:    ret

  tail call void @func(i64 0, i64 0, i64 0, i64 0, i64 0, i128 %arg1, i128 %arg2)

  ret void