github.com/axw/llgo@v0.0.0-20160805011314-95b5fe4dca20/irgen/utils.go (about)

     1  //===- utils.go - misc utils ----------------------------------------------===//
     2  //
     3  //                     The LLVM Compiler Infrastructure
     4  //
     5  // This file is distributed under the University of Illinois Open Source
     6  // License. See LICENSE.TXT for details.
     7  //
     8  //===----------------------------------------------------------------------===//
     9  //
    10  // This file implements misellaneous utilities for IR generation.
    11  //
    12  //===----------------------------------------------------------------------===//
    13  
    14  package irgen
    15  
    16  import (
    17  	"llvm.org/llgo/third_party/gotools/go/types"
    18  	"llvm.org/llvm/bindings/go/llvm"
    19  )
    20  
    21  func (fr *frame) loadOrNull(cond, ptr llvm.Value, ty types.Type) *govalue {
    22  	startbb := fr.builder.GetInsertBlock()
    23  	loadbb := llvm.AddBasicBlock(fr.function, "")
    24  	contbb := llvm.AddBasicBlock(fr.function, "")
    25  	fr.builder.CreateCondBr(cond, loadbb, contbb)
    26  
    27  	fr.builder.SetInsertPointAtEnd(loadbb)
    28  	llty := fr.types.ToLLVM(ty)
    29  	typedptr := fr.builder.CreateBitCast(ptr, llvm.PointerType(llty, 0), "")
    30  	loadedval := fr.builder.CreateLoad(typedptr, "")
    31  	fr.builder.CreateBr(contbb)
    32  
    33  	fr.builder.SetInsertPointAtEnd(contbb)
    34  	llv := fr.builder.CreatePHI(llty, "")
    35  	llv.AddIncoming(
    36  		[]llvm.Value{llvm.ConstNull(llty), loadedval},
    37  		[]llvm.BasicBlock{startbb, loadbb},
    38  	)
    39  	return newValue(llv, ty)
    40  }