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This patch enable the function multiversion(FMV) and `target_clones` attribute for RISC-V target. The proposal of `target_clones` syntax can be found at the https://github.com/riscv-non-isa/riscv-c-api-doc/pull/48 (which has landed), as modified by the proposed https://github.com/riscv-non-isa/riscv-c-api-doc/pull/85 (which adds the priority syntax). It supports the `target_clones` function attribute and function multiversioning feature for RISC-V target. It will generate the ifunc resolver function for the function that declared with target_clones attribute. The resolver function will check the version support by runtime object `__riscv_feature_bits`. For example: ``` __attribute__((target_clones("default", "arch=+ver1", "arch=+ver2"))) int bar() { return 1; } ``` the corresponding resolver will be like: ``` bar.resolver() { __init_riscv_feature_bits(); // Check arch=+ver1 if ((__riscv_feature_bits.features[0] & BITMASK_OF_VERSION1) == BITMASK_OF_VERSION1) { return bar.arch=+ver1; } else { // Check arch=+ver2 if ((__riscv_feature_bits.features[0] & BITMASK_OF_VERSION2) == BITMASK_OF_VERSION2) { return bar.arch=+ver2; } else { // Default return bar.default; } } } ```
9 lines
336 B
C
9 lines
336 B
C
// RUN: not %clang_cc1 -triple riscv64 -target-feature +i -emit-llvm -o - %s 2>&1 | FileCheck %s --check-prefix=CHECK-UNSUPPORT-OS
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// CHECK-UNSUPPORT-OS: error: function multiversioning is currently only supported on Linux
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__attribute__((target_clones("default", "arch=+c"))) int foo(void) {
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return 2;
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}
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int bar() { return foo(); }
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