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308e2db83d
Summary:
This patch makes sure that the field VFShape.VF is greater than zero
when demangling the vector function name of scalable vector functions
encoded in the "vector-function-abi-variant" attribute.
This change is required to be able to provide instances of VFShape
that can be used to query the VFDatabase for the vectorization passes,
as such passes always require a positive value for the Vectorization Factor (VF)
needed by the vectorization process.
It is not possible to extract the value of VFShape.VF from the mangled
name of scalable vector functions, because it is encoded as
`x`. Therefore, the VFABI demangling function has been modified to
extract such information from the IR declaration of the vector
function, under the assumption that _all_ vectors in the signature of
the vector function have the same number of lanes. Such assumption is
valid because it is also assumed by the Vector Function ABI
specifications supported by the demangling function (x86, AArch64, and
LLVM internal one).
The unit tests that demangle scalable names have been modified by
adding the IR module that carries the declaration of the vector
function name being demangled.
In particular, the demangling function fails in the following cases:
1. When the declaration of the scalable vector function is not
present in the module.
2. When the value of VFSHape.VF is not greater than 0.
Reviewers: jdoerfert, sdesmalen, andwar
Reviewed By: jdoerfert
Subscribers: mgorny, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73286
42 lines
1.7 KiB
C++
42 lines
1.7 KiB
C++
//===-- vfabi-demangler-fuzzer.cpp - Fuzzer VFABI using lib/Fuzzer ------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Build tool to fuzz the demangler for the vector function ABI names.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/VectorUtils.h"
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#include "llvm/AsmParser/Parser.h"
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using namespace llvm;
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
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LLVMContext Ctx;
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SMDiagnostic Err;
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const std::unique_ptr<Module> M =
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parseAssemblyString("declare i32 @foo(i32 )\n", Err, Ctx);
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const StringRef MangledName((const char *)Data, Size);
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// Make sure that whatever symbol the demangler is operating on is
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// present in the module (the signature is not important). This is
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// because `tryDemangleForVFABI` fails if the function is not
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// present. We need to make sure we can even invoke
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// `getOrInsertFunction` because such method asserts on strings with
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// zeroes.
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if (!MangledName.empty() && MangledName.find_first_of(0) == StringRef::npos)
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M->getOrInsertFunction(
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MangledName,
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FunctionType::get(Type::getVoidTy(M->getContext()), false));
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const auto Info = VFABI::tryDemangleForVFABI(MangledName, *M);
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// Do not optimize away the return value. Inspired by
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// https://github.com/google/benchmark/blob/master/include/benchmark/benchmark.h#L307-L345
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asm volatile("" : : "r,m"(Info) : "memory");
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return 0;
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}
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