llvmjit_wrap.cpp

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/*-------------------------------------------------------------------------
 *
 * llvmjit_wrap.cpp
 *    Parts of the LLVM interface not (yet) exposed to C.
 *
 * Copyright (c) 2016-2023, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/backend/lib/llvm/llvmjit_wrap.cpp
 *
 *-------------------------------------------------------------------------
 */
 
extern "C"
{
#include "postgres.h"
}
 
#include <llvm-c/Core.h>
 
/* Avoid macro clash with LLVM's C++ headers */
#undef Min
 
#include <llvm/IR/Attributes.h>
#include <llvm/IR/Function.h>
#include <llvm/MC/SubtargetFeature.h>
#include <llvm/Support/Host.h>
 
#include "jit/llvmjit.h"
 
 
/*
 * C-API extensions.
 */
#if defined(HAVE_DECL_LLVMGETHOSTCPUNAME) && !HAVE_DECL_LLVMGETHOSTCPUNAME
char *LLVMGetHostCPUName(void) {
    return strdup(llvm::sys::getHostCPUName().data());
}
#endif
 
 
#if defined(HAVE_DECL_LLVMGETHOSTCPUFEATURES) && !HAVE_DECL_LLVMGETHOSTCPUFEATURES
char *LLVMGetHostCPUFeatures(void) {
    llvm::SubtargetFeatures Features;
    llvm::StringMap<bool> HostFeatures;
 
    if (llvm::sys::getHostCPUFeatures(HostFeatures))
        for (auto &F : HostFeatures)
            Features.AddFeature(F.first(), F.second);
 
    return strdup(Features.getString().c_str());
}
#endif
 
/*
 * Like LLVM's LLVMGetAttributeCountAtIndex(), works around a bug in LLVM 3.9.
 *
 * In LLVM <= 3.9, LLVMGetAttributeCountAtIndex() segfaults if there are no
 * attributes at an index (fixed in LLVM commit ce9bb1097dc2).
 */
unsigned
LLVMGetAttributeCountAtIndexPG(LLVMValueRef F, uint32 Idx)
{
    /*
     * This is more expensive, so only do when using a problematic LLVM
     * version.
     */
#if LLVM_VERSION_MAJOR < 4
    if (!llvm::unwrap<llvm::Function>(F)->getAttributes().hasAttributes(Idx))
        return 0;
#endif
 
    /*
     * There is no nice public API to determine the count nicely, so just
     * always fall back to LLVM's C API.
     */
    return LLVMGetAttributeCountAtIndex(F, Idx);
}