<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Does the C API have an equivalent of stack storage? Via the C++ APIs one can shove the string constant on the stack via<div>a store instruction operation on an alloca instruction--the address needed is the alloca. For example:</div><div><br></div><div>llvm::Value* stringVar = builder.CreateAlloca(stringConstant->getType());<br>builder.CreateStore(stringConstant, stringVar);</div><div><br></div><div>The stringVar is your address.</div><div><br></div><div>Garrison<br><div><div><br><div><div><div>On Jan 11, 2010, at 10:07, James Williams wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi,<br><br>I've read <a href="http://llvm.org/docs/LangRef.html#t_array" target="_blank">http://llvm.org/docs/LangRef.html#t_array</a> and <a href="http://llvm.org/docs/GetElementPtr.html" target="_blank">http://llvm.org/docs/GetElementPtr.html</a> and if I've understood right there are no operations that act directly on arrays - instead I need to use getelementptr on a pointer to an array to get a pointer to an array element. I also understand that there is no 'address of' operation.<br>
<br>As a result I can't figure out how to use constant derived types without assigning them to a global. Say I want to use the C bindings function LLVMValueRef LLVMConstString(char *, int, int) to get an int8* pointer to a C string constant - there doesn't seem to be any way to directly use the resulting [N x i8] value directly and there's no operator that gives me its address.<br>
<br>The only way I can see to get a pointer to the string constant array is to go through a global variable, for example:<br><br>g = LLVMAddGlobal(module, LLVMTypeOf(v), "__string_" + string_literal_number);<br>
string_literal_number = string_literal_number + 1;<br>v = LLVMConstString(string_literal, string_literal.Length, 0);<br>LLVMSetInitializer(g, v);<br>elements = { LLVMConstInt(LLVMInt32Type(), 0L, 0), LLVMConstInt(LLVMInt32Type(), 0L, 0) };<br>
return LLVMConstInBoundsGEP(g, elements, 2);<br><br>Is it possible to get the address of an element of a constant
array or struct without first initializing a global variable to the constant?<br>
<br>Thanks in advance,<br>-- James Williams<br>
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