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llvm-mirror/test/CodeGen/AArch64/tailcall-string-rvo.ll
Jessica Paquette d84c7b0582 [AArch64][GlobalISel] Support sibling calls with outgoing arguments
This adds support for lowering sibling calls with outgoing arguments.

e.g

```
define void @foo(i32 %a)
```

Support is ported from AArch64ISelLowering's `isEligibleForTailCallOptimization`.
The only thing that is missing is a full port of
`TargetLowering::parametersInCSRMatch`. So, if we're using swiftself,
we'll never tail call.

- Rename `analyzeCallResult` to `analyzeArgInfo`, since the function is now used
  for both outgoing and incoming arguments
- Teach `OutgoingArgHandler` about tail calls. Tail calls use frame indices for
  stack arguments.
- Teach `lowerFormalArguments` to set the bytes in the caller's stack argument
  area. This is used later to check if the tail call's parameters will fit on
  the caller's stack.
- Add `areCalleeOutgoingArgsTailCallable` to perform the eligibility check on
  the callee's outgoing arguments.

For testing:

- Update call-translator-tail-call to verify that we can now tail call with
  outgoing arguments, use G_FRAME_INDEX for stack arguments, and respect the
  size of the caller's stack
- Remove GISel-specific check lines from speculation-hardening.ll, since GISel
  now tail calls like the other selectors
- Add a GISel test line to tailcall-string-rvo.ll since we can tail call in that
  test now
- Add a GISel test line to tailcall_misched_graph.ll since we tail call there
  now. Add specific check lines for GISel, since the debug output from the
  machine-scheduler differs with GlobalISel. The dependency still holds, but
  the output comes out in a different order.

Differential Revision: https://reviews.llvm.org/D67471

llvm-svn: 371780
2019-09-12 22:10:36 +00:00

49 lines
2.3 KiB
LLVM

; RUN: llc -relocation-model=static -verify-machineinstrs -O2 < %s | FileCheck %s
; RUN: llc -relocation-model=static -verify-machineinstrs -global-isel -O2 < %s | FileCheck %s
; The call to function TestBar should be a tail call, when in C++ the string
; `ret` is RVO returned.
; string TestFoo() {
; string ret = undef;
; TestBar(&ret); // tail call optimized
; return ret;
; }
target triple = "aarch64-linux-gnu"
%class.basic_string.11.42.73 = type { %"class.__gnu_cxx::__versa_string.10.41.72" }
%"class.__gnu_cxx::__versa_string.10.41.72" = type { %"class.__gnu_cxx::__sso_string_base.9.40.71" }
%"class.__gnu_cxx::__sso_string_base.9.40.71" = type { %"struct.__gnu_cxx::__vstring_utility<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider.7.38.69", i64, %union.anon.8.39.70 }
%"struct.__gnu_cxx::__vstring_utility<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider.7.38.69" = type { i8* }
%union.anon.8.39.70 = type { i64, [8 x i8] }
declare void @TestBaz(%class.basic_string.11.42.73* noalias sret %arg)
define void @TestBar(%class.basic_string.11.42.73* noalias sret %arg) {
bb:
call void @TestBaz(%class.basic_string.11.42.73* noalias sret %arg)
ret void
}
define void @TestFoo(%class.basic_string.11.42.73* noalias sret %arg) {
; CHECK-LABEL: TestFoo:
; CHECK: b TestBar
bb:
%tmp = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 2
%tmp1 = bitcast %class.basic_string.11.42.73* %arg to %union.anon.8.39.70**
store %union.anon.8.39.70* %tmp, %union.anon.8.39.70** %tmp1, align 8
%tmp2 = bitcast %union.anon.8.39.70* %tmp to i8*
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp2, i8* nonnull undef, i64 13, i1 false)
%tmp3 = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 1
store i64 13, i64* %tmp3, align 8
%tmp4 = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 2, i32 1, i64 5
store i8 0, i8* %tmp4, align 1
tail call void @TestBar(%class.basic_string.11.42.73* noalias sret %arg)
ret void
}
; Function Attrs: argmemonly nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i1) #0
attributes #0 = { argmemonly nounwind }