r246229 - [X86] Conditionalize Darwin MaxVectorAlign on the presence of AVX.
Ahmed Bougacha via cfe-commits
cfe-commits at lists.llvm.org
Mon Aug 31 16:03:19 PDT 2015
On Thu, Aug 27, 2015 at 7:19 PM, Eric Christopher <echristo at gmail.com>
wrote:
> 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.
>
You're right; any ideas on how to handle this? In particular, has any of
IRGen (except attributes of course) needed to know about it until know?
IIRC it's directly lowered to IR function attributes, so this sounds like a
big change. Worst case we can restore the unconditional max alignment?
> Also, should we do this for all of the x86 OSes?
>
I'm not sure: MaxVectorAlign was only set for the Darwin targets, but I
think it would make sense everywhere.
Let's see what people say: http://reviews.llvm.org/D12505
Thanks for the comments!
-Ahmed
> -eric
>
> On Thu, Aug 27, 2015 at 3:31 PM Ahmed Bougacha via cfe-commits <
> cfe-commits at 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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>
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