[llvm] r215600 - [AArch64, fast-isel] Fall back to SelectionDAG to select tail calls.

[Chad Rosier]

Hi Akira,
Would it be possible to narrow the scope to only those tail calls that
require special handling?  Or is it that the front-end will only emit tail
calls for those calls that require it at -O0?  Please clarify.

 Chad

> Author: ahatanak
> Date: Wed Aug 13 18:23:58 2014
> New Revision: 215600
>
> URL: http://llvm.org/viewvc/llvm-project?rev=215600&view=rev
> Log:
> [AArch64, fast-isel] Fall back to SelectionDAG to select tail calls.
>
> Certain functions such as objc_autoreleaseReturnValue have to be called as
> tail-calls even at -O0. Since normal fast-isel doesn't emit calls as tail
> calls,
> we have to fall back to SelectionDAG to select calls that are marked as
> tail.
>
> <rdar://problem/17991614>
>
>
> Added:
>     llvm/trunk/test/CodeGen/AArch64/tailcall-fastisel.ll
> Modified:
>     llvm/trunk/lib/Target/AArch64/AArch64FastISel.cpp
>     llvm/trunk/test/CodeGen/AArch64/arm64-abi_align.ll
>
> Modified: llvm/trunk/lib/Target/AArch64/AArch64FastISel.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64FastISel.cpp?rev=215600&r1=215599&r2=215600&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/AArch64/AArch64FastISel.cpp (original)
> +++ llvm/trunk/lib/Target/AArch64/AArch64FastISel.cpp Wed Aug 13 18:23:58
> 2014
> @@ -1687,10 +1687,15 @@ bool AArch64FastISel::FinishCall(CallLow
>
>  bool AArch64FastISel::FastLowerCall(CallLoweringInfo &CLI) {
>    CallingConv::ID CC  = CLI.CallConv;
> +  bool IsTailCall     = CLI.IsTailCall;
>    bool IsVarArg       = CLI.IsVarArg;
>    const Value *Callee = CLI.Callee;
>    const char *SymName = CLI.SymName;
>
> +  // Allow SelectionDAG isel to handle tail calls.
> +  if (IsTailCall)
> +    return false;
> +
>    CodeModel::Model CM = TM.getCodeModel();
>    // Only support the small and large code model.
>    if (CM != CodeModel::Small && CM != CodeModel::Large)
>
> Modified: llvm/trunk/test/CodeGen/AArch64/arm64-abi_align.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/arm64-abi_align.ll?rev=215600&r1=215599&r2=215600&view=diff
> ==============================================================================
> --- llvm/trunk/test/CodeGen/AArch64/arm64-abi_align.ll (original)
> +++ llvm/trunk/test/CodeGen/AArch64/arm64-abi_align.ll Wed Aug 13 18:23:58
> 2014
> @@ -511,7 +511,9 @@ entry:
>  ; CHECK: str {{w[0-9]+}}, [sp]
>  ; FAST-LABEL: i64_split
>  ; FAST: ldr x7, [{{x[0-9]+}}]
> -; FAST: str {{w[0-9]+}}, [sp]
> +; FAST: mov x[[R0:[0-9]+]], sp
> +; FAST: orr w[[R1:[0-9]+]], wzr, #0x8
> +; FAST: str w[[R1]], {{\[}}x[[R0]]{{\]}}
>    %0 = load i64* bitcast (%struct.s41* @g41 to i64*), align 16
>    %call = tail call i32 @callee_i64(i32 1, i32 2, i32 3, i32 4, i32 5,
>                                      i32 6, i32 7, i64 %0, i32 8) #5
>
> Added: llvm/trunk/test/CodeGen/AArch64/tailcall-fastisel.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/tailcall-fastisel.ll?rev=215600&view=auto
> ==============================================================================
> --- llvm/trunk/test/CodeGen/AArch64/tailcall-fastisel.ll (added)
> +++ llvm/trunk/test/CodeGen/AArch64/tailcall-fastisel.ll Wed Aug 13
> 18:23:58 2014
> @@ -0,0 +1,11 @@
> +; RUN: llc < %s -mtriple=arm64-apple-darwin -O0 | FileCheck %s
> +
> +; CHECK: b _foo0
> +
> +define i32 @foo1() {
> +entry:
> +  %call = tail call i32 @foo0()
> +  ret i32 %call
> +}
> +
> +declare i32 @foo0()
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>


-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation