Hi Ahmed,
A quick note: I think this is going to fail in the presence of the target
attribute. I.e. if someone decorates a function with
__attribute__((target("avx512"))) this is unlikely to catch that.
Also, should we do this for all of the x86 OSes?
-eric
On Thu, Aug 27, 2015 at 3:31 PM Ahmed Bougacha via cfe-commits <
cfe-commits@lists.llvm.org> wrote:
> Author: ab
> Date: Thu Aug 27 17:30:38 2015
> New Revision: 246229
>
> URL: http://llvm.org/viewvc/llvm-project?rev=246229&view=rev
> Log:
> [X86] Conditionalize Darwin MaxVectorAlign on the presence of AVX.
>
> There's no point in using a larger alignment if we have no instructions
> that would benefit from it.
>
> Differential Revision: http://reviews.llvm.org/D12389
>
> Modified:
> cfe/trunk/lib/Basic/Targets.cpp
> cfe/trunk/test/CodeGen/vector-alignment.c
>
> Modified: cfe/trunk/lib/Basic/Targets.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Targets.cpp?rev=246229&r1=246228&r2=246229&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Basic/Targets.cpp (original)
> +++ cfe/trunk/lib/Basic/Targets.cpp Thu Aug 27 17:30:38 2015
> @@ -3629,13 +3629,21 @@ public:
> LongDoubleWidth = 128;
> LongDoubleAlign = 128;
> SuitableAlign = 128;
> - MaxVectorAlign = 256;
> SizeType = UnsignedLong;
> IntPtrType = SignedLong;
> DataLayoutString = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128";
> HasAlignMac68kSupport = true;
> }
>
> + bool handleTargetFeatures(std::vector<std::string> &Features,
> + DiagnosticsEngine &Diags) override {
> + if
> (!DarwinTargetInfo<X86_32TargetInfo>::handleTargetFeatures(Features,
> + Diags))
> + return false;
> + // Now that we know if we have AVX, we can decide how to align
> vectors.
> + MaxVectorAlign = hasFeature("avx") ? 256 : 128;
> + return true;
> + }
> };
>
> // x86-32 Windows target
> @@ -3986,13 +3994,22 @@ public:
> DarwinX86_64TargetInfo(const llvm::Triple &Triple)
> : DarwinTargetInfo<X86_64TargetInfo>(Triple) {
> Int64Type = SignedLongLong;
> - MaxVectorAlign = 256;
> // The 64-bit iOS simulator uses the builtin bool type for
> Objective-C.
> llvm::Triple T = llvm::Triple(Triple);
> if (T.isiOS())
> UseSignedCharForObjCBool = false;
> DataLayoutString = "e-m:o-i64:64-f80:128-n8:16:32:64-S128";
> }
> +
> + bool handleTargetFeatures(std::vector<std::string> &Features,
> + DiagnosticsEngine &Diags) override {
> + if
> (!DarwinTargetInfo<X86_64TargetInfo>::handleTargetFeatures(Features,
> + Diags))
> + return false;
> + // Now that we know if we have AVX, we can decide how to align
> vectors.
> + MaxVectorAlign = hasFeature("avx") ? 256 : 128;
> + return true;
> + }
> };
>
> class OpenBSDX86_64TargetInfo : public
> OpenBSDTargetInfo<X86_64TargetInfo> {
>
> Modified: cfe/trunk/test/CodeGen/vector-alignment.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/vector-alignment.c?rev=246229&r1=246228&r2=246229&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/CodeGen/vector-alignment.c (original)
> +++ cfe/trunk/test/CodeGen/vector-alignment.c Thu Aug 27 17:30:38 2015
> @@ -1,38 +1,51 @@
> -// RUN: %clang_cc1 -w -triple x86_64-apple-darwin10 -emit-llvm -o - %s |
> FileCheck %s
> +// RUN: %clang_cc1 -w -triple x86_64-apple-darwin10 \
> +// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL
> --check-prefix=SSE
> +// RUN: %clang_cc1 -w -triple i386-apple-darwin10 \
> +// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL
> --check-prefix=SSE
> +// RUN: %clang_cc1 -w -triple x86_64-apple-darwin10 -target-feature +avx \
> +// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL
> --check-prefix=AVX
> +// RUN: %clang_cc1 -w -triple i386-apple-darwin10 -target-feature +avx \
> +// RUN: -emit-llvm -o - %s | FileCheck %s --check-prefix=ALL
> --check-prefix=AVX
> // rdar://11759609
>
> // At or below target max alignment with no aligned attribute should
> align based
> // on the size of vector.
> double __attribute__((vector_size(16))) v1;
> -// CHECK: @v1 {{.*}}, align 16
> +// SSE: @v1 {{.*}}, align 16
> +// AVX: @v1 {{.*}}, align 16
> double __attribute__((vector_size(32))) v2;
> -// CHECK: @v2 {{.*}}, align 32
> +// SSE: @v2 {{.*}}, align 16
> +// AVX: @v2 {{.*}}, align 32
>
> // Alignment above target max alignment with no aligned attribute should
> align
> // based on the target max.
> double __attribute__((vector_size(64))) v3;
> -// CHECK: @v3 {{.*}}, align 32
> +// SSE: @v3 {{.*}}, align 16
> +// AVX: @v3 {{.*}}, align 32
> double __attribute__((vector_size(1024))) v4;
> -// CHECK: @v4 {{.*}}, align 32
> +// SSE: @v4 {{.*}}, align 16
> +// AVX: @v4 {{.*}}, align 32
>
> // Aliged attribute should always override.
> double __attribute__((vector_size(16), aligned(16))) v5;
> -// CHECK: @v5 {{.*}}, align 16
> +// ALL: @v5 {{.*}}, align 16
> double __attribute__((vector_size(16), aligned(64))) v6;
> -// CHECK: @v6 {{.*}}, align 64
> +// ALL: @v6 {{.*}}, align 64
> double __attribute__((vector_size(32), aligned(16))) v7;
> -// CHECK: @v7 {{.*}}, align 16
> +// ALL: @v7 {{.*}}, align 16
> double __attribute__((vector_size(32), aligned(64))) v8;
> -// CHECK: @v8 {{.*}}, align 64
> +// ALL: @v8 {{.*}}, align 64
>
> // Check non-power of 2 widths.
> double __attribute__((vector_size(24))) v9;
> -// CHECK: @v9 {{.*}}, align 32
> +// SSE: @v9 {{.*}}, align 16
> +// AVX: @v9 {{.*}}, align 32
> double __attribute__((vector_size(40))) v10;
> -// CHECK: @v10 {{.*}}, align 32
> +// SSE: @v10 {{.*}}, align 16
> +// AVX: @v10 {{.*}}, align 32
>
> // Check non-power of 2 widths with aligned attribute.
> double __attribute__((vector_size(24), aligned(64))) v11;
> -// CHECK: @v11 {{.*}}, align 64
> +// ALL: @v11 {{.*}}, align 64
> double __attribute__((vector_size(80), aligned(16))) v12;
> -// CHECK: @v12 {{.*}}, align 16
> +// ALL: @v12 {{.*}}, align 16
>
>
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