7852ebc088
Before llvm20, (void)__sync_fetch_and_add(...) always generates locked xadd insns. In linux kernel upstream discussion [1], it is found that for arm64 architecture, the original semantics of (void)__sync_fetch_and_add(...), i.e., __atomic_fetch_add(...), is preferred in order for jit to emit proper native barrier insns. In llvm commits [2] and [3], (void)__sync_fetch_and_add(...) will generate the following insns: - for cpu v1/v2: locked xadd insns to keep backward compatibility - for cpu v3/v4: __atomic_fetch_add() insns To ensure proper barrier semantics for (void)__sync_fetch_and_add(...), cpu v3/v4 is recommended. This patch enables cpu=v3 as the default cpu version. For users wanting to use cpu v1, -mcpu=v1 needs to be explicitly added to clang/llc command line. [1] https://lore.kernel.org/bpf/ZqqiQQWRnz7H93Hc@google.com/T/#mb68d67bc8f39e35a0c3db52468b9de59b79f021f [2] https://github.com/llvm/llvm-project/pull/101428 [3] https://github.com/llvm/llvm-project/pull/106494
104 lines
2.1 KiB
C
104 lines
2.1 KiB
C
// RUN: %clang -E -target bpfel -mcpu=v1 -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_NO %s
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// RUN: %clang -E -target bpfeb -mcpu=v1 -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_NO %s
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// RUN: %clang -E -target bpfel -mcpu=v1 -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_V1 %s
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// RUN: %clang -E -target bpfel -mcpu=v2 -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_V2 %s
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// RUN: %clang -E -target bpfel -mcpu=v3 -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_V3 %s
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// RUN: %clang -E -target bpfel -mcpu=v4 -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_V4 %s
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// RUN: %clang -E -target bpfel -mcpu=generic -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_GENERIC %s
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// RUN: %clang -E -target bpfel -mcpu=probe -x c -o - %s | FileCheck -check-prefix=CHECK -check-prefix=CPU_PROBE %s
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#ifdef __bpf__
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int b;
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#endif
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#ifdef __BPF__
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int c;
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#endif
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#ifdef bpf
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int d;
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#endif
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#ifdef __BPF_CPU_VERSION__
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int e;
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#endif
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#if __BPF_CPU_VERSION__ == 0
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int f;
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#endif
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#if __BPF_CPU_VERSION__ == 1
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int g;
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#endif
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#if __BPF_CPU_VERSION__ == 2
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int h;
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#endif
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#if __BPF_CPU_VERSION__ == 3
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int i;
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#endif
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#if __BPF_CPU_VERSION__ == 4
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int j;
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#endif
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#ifdef __BPF_FEATURE_JMP_EXT
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int k;
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#endif
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#ifdef __BPF_FEATURE_JMP32
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int l;
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#endif
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#ifdef __BPF_FEATURE_ALU32
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int m;
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#endif
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#ifdef __BPF_FEATURE_LDSX
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int n;
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#endif
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#ifdef __BPF_FEATURE_MOVSX
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int o;
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#endif
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#ifdef __BPF_FEATURE_BSWAP
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int p;
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#endif
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#ifdef __BPF_FEATURE_SDIV_SMOD
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int q;
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#endif
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#ifdef __BPF_FEATURE_GOTOL
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int r;
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#endif
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#ifdef __BPF_FEATURE_ST
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int s;
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#endif
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#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
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int t;
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#endif
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// CHECK: int b;
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// CHECK: int c;
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// CHECK-NOT: int d;
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// CHECK: int e;
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// CPU_NO: int g;
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// CPU_V1: int g;
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// CPU_V2: int h;
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// CPU_V2: int k;
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// CPU_V3: int i;
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// CPU_V3: int k;
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// CPU_V3: int l;
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// CPU_V3: int m;
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// CPU_V4: int j;
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// CPU_V4: int k;
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// CPU_V4: int l;
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// CPU_V4: int m;
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// CPU_V4: int n;
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// CPU_V4: int o;
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// CPU_V4: int p;
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// CPU_V4: int q;
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// CPU_V4: int r;
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// CPU_V4: int s;
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// CPU_V1: int t;
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// CPU_V2: int t;
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// CPU_V3: int t;
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// CPU_V4: int t;
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// CPU_GENERIC: int g;
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// CPU_PROBE: int f;
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