[PATCH] D11463: [AArch64] Define subtarget feature "reserve-x18"

[Eric Christopher]

So you're defining it to true here and only have an option to set it to
true from the front end.

How would you turn it off? :)

-eric

On Thu, Jul 23, 2015 at 8:16 AM Akira Hatanaka <ahatanak at gmail.com> wrote:

> ahatanak created this revision.
> ahatanak added reviewers: echristo, dexonsmith.
> ahatanak added a subscriber: llvm-commits.
> Herald added subscribers: rengolin, aemerson.
>
> This patch defines a subtarget feature "reserve-x18" and uses it to decide
> whether X18 should be reserved.
>
> The clang-side patch which makes changes to pass a subtarget feature
> instead of a backend option is here: http://reviews.llvm.org/D11462
>
> http://reviews.llvm.org/D11463
>
> Files:
>   lib/Target/AArch64/AArch64.td
>   lib/Target/AArch64/AArch64RegisterInfo.cpp
>   lib/Target/AArch64/AArch64Subtarget.h
>   test/CodeGen/AArch64/arm64-platform-reg.ll
>
> Index: test/CodeGen/AArch64/arm64-platform-reg.ll
> ===================================================================
> --- test/CodeGen/AArch64/arm64-platform-reg.ll
> +++ test/CodeGen/AArch64/arm64-platform-reg.ll
> @@ -1,5 +1,5 @@
>  ; RUN: llc -mtriple=arm64-apple-ios -o - %s | FileCheck %s
> --check-prefix=CHECK-RESERVE-X18
> -; RUN: llc -mtriple=arm64-freebsd-gnu -aarch64-reserve-x18 -o - %s |
> FileCheck %s --check-prefix=CHECK-RESERVE-X18
> +; RUN: llc -mtriple=arm64-freebsd-gnu -mattr=+reserve-x18 -o - %s |
> FileCheck %s --check-prefix=CHECK-RESERVE-X18
>  ; RUN: llc -mtriple=arm64-linux-gnu -o - %s | FileCheck %s
>
>  ; x18 is reserved as a platform register on Darwin but not on other
> Index: lib/Target/AArch64/AArch64Subtarget.h
> ===================================================================
> --- lib/Target/AArch64/AArch64Subtarget.h
> +++ lib/Target/AArch64/AArch64Subtarget.h
> @@ -51,6 +51,9 @@
>    // HasZeroCycleZeroing - Has zero-cycle zeroing instructions.
>    bool HasZeroCycleZeroing;
>
> +  // ReserveX18 - X18 is not available as a general purpose register.
> +  bool ReserveX18;
> +
>    bool IsLittle;
>
>    /// CPUString - String name of used CPU.
> @@ -101,6 +104,7 @@
>
>    bool hasZeroCycleZeroing() const { return HasZeroCycleZeroing; }
>
> +  bool isX18Reserved() const { return ReserveX18; }
>    bool hasFPARMv8() const { return HasFPARMv8; }
>    bool hasNEON() const { return HasNEON; }
>    bool hasCrypto() const { return HasCrypto; }
> Index: lib/Target/AArch64/AArch64RegisterInfo.cpp
> ===================================================================
> --- lib/Target/AArch64/AArch64RegisterInfo.cpp
> +++ lib/Target/AArch64/AArch64RegisterInfo.cpp
> @@ -34,10 +34,6 @@
>  #define GET_REGINFO_TARGET_DESC
>  #include "AArch64GenRegisterInfo.inc"
>
> -static cl::opt<bool>
> -ReserveX18("aarch64-reserve-x18", cl::Hidden,
> -          cl::desc("Reserve X18, making it unavailable as GPR"));
> -
>  AArch64RegisterInfo::AArch64RegisterInfo(const Triple &TT)
>      : AArch64GenRegisterInfo(AArch64::LR), TT(TT) {}
>
> @@ -104,7 +100,7 @@
>      Reserved.set(AArch64::W29);
>    }
>
> -  if (TT.isOSDarwin() || ReserveX18) {
> +  if (TT.isOSDarwin() ||
> MF.getSubtarget<AArch64Subtarget>().isX18Reserved()) {
>      Reserved.set(AArch64::X18); // Platform register
>      Reserved.set(AArch64::W18);
>    }
> @@ -131,7 +127,8 @@
>      return true;
>    case AArch64::X18:
>    case AArch64::W18:
> -    return TT.isOSDarwin() || ReserveX18;
> +    return TT.isOSDarwin() ||
> +           MF.getSubtarget<AArch64Subtarget>().isX18Reserved();
>    case AArch64::FP:
>    case AArch64::W29:
>      return TFI->hasFP(MF) || TT.isOSDarwin();
> @@ -402,9 +399,11 @@
>    case AArch64::GPR32commonRegClassID:
>    case AArch64::GPR64commonRegClassID:
>      return 32 - 1                                // XZR/SP
> -           - (TFI->hasFP(MF) || TT.isOSDarwin()) // FP
> -           - (TT.isOSDarwin() || ReserveX18) // X18 reserved as platform
> register
> -           - hasBasePointer(MF);           // X19
> +      - (TFI->hasFP(MF) || TT.isOSDarwin()) // FP
> +      - (TT.isOSDarwin() ||
> +         MF.getSubtarget<AArch64Subtarget>()
> +             .isX18Reserved()) // X18 reserved as platform register
> +      - hasBasePointer(MF);    // X19
>    case AArch64::FPR8RegClassID:
>    case AArch64::FPR16RegClassID:
>    case AArch64::FPR32RegClassID:
> Index: lib/Target/AArch64/AArch64.td
> ===================================================================
> --- lib/Target/AArch64/AArch64.td
> +++ lib/Target/AArch64/AArch64.td
> @@ -40,6 +40,10 @@
>  def FeatureZCZeroing : SubtargetFeature<"zcz", "HasZeroCycleZeroing",
> "true",
>                                          "Has zero-cycle zeroing
> instructions">;
>
> +def FeatureReserveX18 : SubtargetFeature<"reserve-x18", "ReserveX18",
> "true",
> +                                         "Reserve X18, making it
> unavailable "
> +                                         "as a GPR">;
> +
>
>  //===----------------------------------------------------------------------===//
>  // Architectures.
>  //
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150723/8b381ce3/attachment.html>