https://github.com/jhuber6 updated
https://github.com/llvm/llvm-project/pull/115241
>From fcb8bcfba329b6ad9f33ace70c22ca4b542d2117 Mon Sep 17 00:00:00 2001
From: Joseph Huber <hube...@outlook.com>
Date: Wed, 6 Nov 2024 18:27:07 -0600
Subject: [PATCH 1/2] [AMDGPU] Make `__GCC_DESTRUCTIVE_SIZE` 128 on AMDGPU
Summary:
The cache line size on AMDGPU varies between 64 and 128 (The lowest L2
cache also goes to 256 on some architectures.) This macro is intended to
present a size that will not cause destructive interference, so we
choose the larger of those values.
---
clang/lib/Basic/Targets/AMDGPU.h | 4 ++++
clang/test/Driver/amdgpu-macros.cl | 2 ++
2 files changed, 6 insertions(+)
diff --git a/clang/lib/Basic/Targets/AMDGPU.h b/clang/lib/Basic/Targets/AMDGPU.h
index 6edd3474d4edae..81e96ed65c47bf 100644
--- a/clang/lib/Basic/Targets/AMDGPU.h
+++ b/clang/lib/Basic/Targets/AMDGPU.h
@@ -462,6 +462,10 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUTargetInfo final :
public TargetInfo {
}
bool hasHIPImageSupport() const override { return HasImage; }
+
+ std::pair<unsigned, unsigned> hardwareInterferenceSizes() const override {
+ return std::make_pair(128, 128);
+ }
};
} // namespace targets
diff --git a/clang/test/Driver/amdgpu-macros.cl
b/clang/test/Driver/amdgpu-macros.cl
index dd5a4483e4d607..2fedd10bb53445 100644
--- a/clang/test/Driver/amdgpu-macros.cl
+++ b/clang/test/Driver/amdgpu-macros.cl
@@ -153,6 +153,8 @@
// ARCH-GCN-DAG: #define __[[FAMILY]]__ 1
// ARCH-GCN-DAG: #define __amdgcn_processor__ "[[CPU]]"
// ARCH-GCN-DAG: #define __AMDGCN_WAVEFRONT_SIZE [[WAVEFRONT_SIZE]]
+// ARCH-GCN-DAG: #define __GCC_DESTRUCTIVE_SIZE 128
+// ARCH-GCN-DAG: #define __GCC_CONSTRUCTIVE_SIZE 128
// UNSAFEFPATOMIC-DAG: #define __AMDGCN_UNSAFE_FP_ATOMICS__ 1
// RUN: %clang -E -dM -target amdgcn -mcpu=gfx906 -mwavefrontsize64 \
>From e50916a8669c2e6431c1926b20bc098bbdec469f Mon Sep 17 00:00:00 2001
From: Joseph Huber <hube...@outlook.com>
Date: Wed, 6 Nov 2024 19:01:54 -0600
Subject: [PATCH 2/2] comments
---
clang/lib/Basic/Targets/AMDGPU.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/clang/lib/Basic/Targets/AMDGPU.h b/clang/lib/Basic/Targets/AMDGPU.h
index 81e96ed65c47bf..fac46f215a3736 100644
--- a/clang/lib/Basic/Targets/AMDGPU.h
+++ b/clang/lib/Basic/Targets/AMDGPU.h
@@ -464,6 +464,10 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUTargetInfo final :
public TargetInfo {
bool hasHIPImageSupport() const override { return HasImage; }
std::pair<unsigned, unsigned> hardwareInterferenceSizes() const override {
+ // This is imprecise as the value can vary between 64, 128 (even 256!)
bytes
+ // depending on the level of cache and the target architecture. We select
+ // the size that corresponds to the largest L1 cache line for all
+ // architectures.
return std::make_pair(128, 128);
}
};
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