[Clang][AArch64]Add FP8 ACLE macros implementation #140591

CarolineConcatto · 2025-05-19T18:35:24Z

This patch implements the macros described in the ACLE[1]

[1] https://github.com/ARM-software/acle/blob/main/main/acle.md#modal-8-bit-floating-point-extensions

This patch implements the macros described in the ACLE[1] [1] https://github.com/ARM-software/acle/blob/main/main/acle.md#modal-8-bit-floating-point-extensions

llvmbot · 2025-05-19T18:35:58Z

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-backend-aarch64

Author: None (CarolineConcatto)

Changes

This patch implements the macros described in the ACLE[1]

[1] https://github.com/ARM-software/acle/blob/main/main/acle.md#modal-8-bit-floating-point-extensions

Full diff: https://github.com/llvm/llvm-project/pull/140591.diff

3 Files Affected:

(modified) clang/lib/Basic/Targets/AArch64.cpp (+59)
(modified) clang/lib/Basic/Targets/AArch64.h (+9)
(modified) clang/test/Preprocessor/aarch64-target-features.c (+31)

diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index e1f6c7b834dc7..7267b17704a41 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -596,6 +596,33 @@ void AArch64TargetInfo::getTargetDefines(const LangOptions &Opts,
   if (HasSMEB16B16)
     Builder.defineMacro("__ARM_FEATURE_SME_B16B16", "1");
 
+  if (HasFP8)
+    Builder.defineMacro("__ARM_FEATURE_FP8", "1");
+
+  if (HasFP8FMA)
+    Builder.defineMacro("__ARM_FEATURE_FP8FMA", "1");
+
+  if (HasFP8DOT2)
+    Builder.defineMacro("__ARM_FEATURE_FP8DOT2", "1");
+
+  if (HasFP8DOT4)
+    Builder.defineMacro("__ARM_FEATURE_FP8DOT4", "1");
+
+  if (HasSSVE_FP8DOT2)
+    Builder.defineMacro("__ARM_FEATURE_SSVE_FP8DOT2", "1");
+
+  if (HasSSVE_FP8DOT4)
+    Builder.defineMacro("__ARM_FEATURE_SSVE_FP8DOT4", "1");
+
+  if (HasSSVE_FP8FMA)
+    Builder.defineMacro("__ARM_FEATURE_SSVE_FP8FMA", "1");
+
+  if (HasSME_F8F32)
+    Builder.defineMacro("__ARM_FEATURE_SME_F8F32", "1");
+
+  if (HasSME_F8F16)
+    Builder.defineMacro("__ARM_FEATURE_SME_F8F16", "1");
+
   if (HasCRC)
     Builder.defineMacro("__ARM_FEATURE_CRC32", "1");
 
@@ -885,6 +912,15 @@ bool AArch64TargetInfo::hasFeature(StringRef Feature) const {
       .Cases("ls64", "ls64_v", "ls64_accdata", HasLS64)
       .Case("wfxt", HasWFxT)
       .Case("rcpc3", HasRCPC3)
+      .Case("fp8", HasFP8)
+      .Case("fp8fma", HasFP8FMA)
+      .Case("fp8dot2", HasFP8DOT2)
+      .Case("fp8dot4", HasFP8DOT4)
+      .Case("ssve-fp8dot2", HasSSVE_FP8DOT2)
+      .Case("ssve-fp8dot4", HasSSVE_FP8DOT4)
+      .Case("ssve-fp8fma", HasSSVE_FP8FMA)
+      .Case("sme-f8f32", HasSME_F8F32)
+      .Case("sme-f8f16", HasSME_F8F16)
       .Default(false);
 }
 
@@ -1046,6 +1082,29 @@ bool AArch64TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasSVEB16B16 = true;
       HasSMEB16B16 = true;
     }
+
+    if (Feature == "+fp8")
+      HasFP8 = true;
+    if (Feature == "+fp8fma")
+      HasFP8FMA = true;
+    if (Feature == "+fp8dot2")
+      HasFP8DOT2 = true;
+    if (Feature == "+fp8dot4")
+      HasFP8DOT4 = true;
+    if (Feature == "+ssve-fp8dot2")
+      HasSSVE_FP8DOT2 = true;
+    if (Feature == "+ssve-fp8dot4")
+      HasSSVE_FP8DOT4 = true;
+    if (Feature == "+ssve-fp8fma")
+      HasSSVE_FP8FMA = true;
+    if (Feature == "+sme-f8f32") {
+      HasSME2 = true;
+      HasSME_F8F32 = true;
+    }
+    if (Feature == "+sme-f8f16") {
+      HasSME2 = true;
+      HasSME_F8F16 = true;
+    }
     if (Feature == "+sb")
       HasSB = true;
     if (Feature == "+predres")
diff --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h
index 6eeac69af20df..7230f22d5bb86 100644
--- a/clang/lib/Basic/Targets/AArch64.h
+++ b/clang/lib/Basic/Targets/AArch64.h
@@ -106,6 +106,15 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   bool HasSMEF16F16 = false;
   bool HasSMEB16B16 = false;
   bool HasSME2p1 = false;
+  bool HasFP8 = false;
+  bool HasFP8FMA = false;
+  bool HasFP8DOT2 = false;
+  bool HasFP8DOT4 = false;
+  bool HasSSVE_FP8DOT2 = false;
+  bool HasSSVE_FP8DOT4 = false;
+  bool HasSSVE_FP8FMA = false;
+  bool HasSME_F8F32 = false;
+  bool HasSME_F8F16 = false;
   bool HasSB = false;
   bool HasPredRes = false;
   bool HasSSBS = false;
diff --git a/clang/test/Preprocessor/aarch64-target-features.c b/clang/test/Preprocessor/aarch64-target-features.c
index 3f801c4344940..52045d216262f 100644
--- a/clang/test/Preprocessor/aarch64-target-features.c
+++ b/clang/test/Preprocessor/aarch64-target-features.c
@@ -744,3 +744,34 @@
 // CHECK-SMEB16B16: __ARM_FEATURE_SME2 1
 // CHECK-SMEB16B16: __ARM_FEATURE_SME_B16B16 1
 // CHECK-SMEB16B16: __ARM_FEATURE_SVE_B16B16 1
+//
+//  RUN: %clang --target=aarch64 -march=armv9-a+fp8 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FP8 %s
+// CHECK-FP8: __ARM_FEATURE_FP8 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+fp8fma -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FP8FMA %s
+// CHECK-FP8FMA: __ARM_FEATURE_FP8FMA 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+fp8dot2 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FP8DOT2 %s
+// CHECK-FP8DOT2: __ARM_FEATURE_FP8DOT2 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+fp8dot4 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-FP8DOT4 %s
+// CHECK-FP8DOT4: __ARM_FEATURE_FP8DOT4 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+ssve-fp8dot2 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SSVE-FP8DOT2 %s
+// CHECK-SSVE-FP8DOT2: __ARM_FEATURE_SSVE_FP8DOT2 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+ssve-fp8dot4 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SSVE-FP8DOT4 %s
+// CHECK-SSVE-FP8DOT4: __ARM_FEATURE_SSVE_FP8DOT4 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+ssve-fp8fma -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SSVE-FP8FMA %s
+// CHECK-SSVE-FP8FMA: __ARM_FEATURE_SSVE_FP8FMA 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+sme-f8f32 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SMEF8F32 %s
+// CHECK-SMEF8F32: __ARM_FEATURE_LOCALLY_STREAMING 1
+// CHECK-SMEF8F32: __ARM_FEATURE_SME2 1
+// CHECK-SMEF8F32: __ARM_FEATURE_SME_F8F32 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+sme-f8f16 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SMEF8F16 %s
+// CHECK-SMEF8F16: __ARM_FEATURE_LOCALLY_STREAMING 1
+// CHECK-SMEF8F16: __ARM_FEATURE_SME2 1
+// CHECK-SMEF8F16: __ARM_FEATURE_SME_F8F16 1

paulwalker-arm · 2025-05-20T10:50:17Z

clang/lib/Basic/Targets/AArch64.cpp

+    if (Feature == "+fp8dot4")
+      HasFP8DOT4 = true;
+    if (Feature == "+ssve-fp8dot2")
+      HasSSVE_FP8DOT2 = true;


This and the other SSVE features should also set HasSME2?

paulwalker-arm · 2025-05-20T10:51:36Z

clang/lib/Basic/Targets/AArch64.cpp

+
+    if (Feature == "+fp8")
+      HasFP8 = true;
+    if (Feature == "+fp8fma")


fp8... feature extensions should also set HasFP8?

I could.
I am not sure I should reproduce the same we have in lib/Target/AArch64/AArch64Features.td also here.
Is that what you are suggestion here?
At first glance it does not look like this is a representation of what we have in
lib/Target/AArch64/AArch64Features.td

I don't fully understand the effect of setting these bools and how the dependencies in AArch64Features.td correspond to setting the feature macros. What I'm mainly after is consistency and so for the SME2 extensions you're setting HasSME2 as well. So I guess the question is why that is necessary? If it's not, then perhaps the way to go is to remove those rather than adding the ones I suggest.

The most important part to verify is that all the feature macros a user would expect to be defined by a specific +feat are in fact defined. If that is managed by AArch64Features.td then great, if not then that would explain why the key feature dependencies are duplicated here.

paulwalker-arm · 2025-05-20T10:56:44Z

clang/test/Preprocessor/aarch64-target-features.c

+// CHECK-SSVE-FP8FMA: __ARM_FEATURE_SSVE_FP8FMA 1
+
+// RUN: %clang --target=aarch64 -march=armv9-a+sme-f8f32 -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SMEF8F32 %s
+// CHECK-SMEF8F32: __ARM_FEATURE_LOCALLY_STREAMING 1


Are the two __ARM_FEATURE_LOCALLY_STREAMING checks relevant for the tests?

Do you mean for the sme-f8f32 and sme-f8f16? If so I was just reproducing what was done for sme-b16b16 and sme-f16f16.

Ok, in which case this is likely an extension of the previous point. If the feature relationships have to be duplicated then it makes sense we verify __ARM_FEATURE_LOCALLY_STREAMING here. If they don't and AArch64Features.td ensures the expected SME feature flags get defined, then we don't need to reverify them here.

[Clang][AArch64]Add FP8 ACLE macros implementation

22e4464

This patch implements the macros described in the ACLE[1] [1] https://github.com/ARM-software/acle/blob/main/main/acle.md#modal-8-bit-floating-point-extensions

CarolineConcatto requested review from labrinea, paulwalker-arm, Lukacma and kmclaughlin-arm May 19, 2025 18:35

llvmbot added clang Clang issues not falling into any other category backend:AArch64 clang:frontend Language frontend issues, e.g. anything involving "Sema" labels May 19, 2025

paulwalker-arm reviewed May 20, 2025

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[Clang][AArch64]Add FP8 ACLE macros implementation #140591

[Clang][AArch64]Add FP8 ACLE macros implementation #140591

CarolineConcatto commented May 19, 2025

llvmbot commented May 19, 2025 •

edited

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[Clang][AArch64]Add FP8 ACLE macros implementation #140591

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[Clang][AArch64]Add FP8 ACLE macros implementation #140591

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