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diff --git a/llvm/docs/LangRef.html b/llvm/docs/LangRef.html index 6ebbb293077..2cf74c2824f 100644 --- a/llvm/docs/LangRef.html +++ b/llvm/docs/LangRef.html @@ -200,6 +200,12 @@ <li><a href="#int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a></li> </ol> </li> + <li><a href="#int_trampoline">Trampoline Intrinsics</a> + <ol> + <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li> + <li><a href="#int_at">'<tt>llvm.adjust.trampoline</tt>' Intrinsic</a></li> + </ol> + </li> <li><a href="#int_general">General intrinsics</a> <ol> <li><a href="#int_var_annotation"> @@ -5123,6 +5129,105 @@ declare void @llvm.memory.barrier( i1 <ll>, i1 <ls>, i1 <sl>, <!-- ======================================================================= --> <div class="doc_subsection"> + <a name="int_trampoline">Trampoline Intrinsics</a> +</div> + +<div class="doc_text"> +<p> + These intrinsics make it possible to excise one parameter, marked with + the <tt>nest</tt> attribute, from a function. The result is a callable + function pointer lacking the nest parameter - the caller does not need + to provide a value for it. Instead, the value to use is stored in + advance in a "trampoline", a block of memory usually allocated + on the stack, which also contains code to splice the nest value into the + argument list. This is used to implement the GCC nested function address + extension. +</p> +<p> + For example, if the function is + <tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function + pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as follows: +<pre> + %tramp1 = alloca [10 x i8], align 4 ; size and alignment only correct for X86 + %tramp = getelementptr [10 x i8]* %tramp1, i32 0, i32 0 + call void @llvm.init.trampoline( i8* %tramp, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval ) + %adj = call i8* @llvm.adjust.trampoline( i8* %tramp ) + %fp = bitcast i8* %adj to i32 (i32, i32)* +</pre> + The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent to + <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>. +</p> +<p> + Trampolines are currently only supported on the X86 architecture. +</p> +</div> + +<!-- _______________________________________________________________________ --> +<div class="doc_subsubsection"> + <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a> +</div> +<div class="doc_text"> +<h5>Syntax:</h5> +<pre> +declare void @llvm.init.trampoline(i8* <tramp>, i8* <func>, i8* <nval>) +</pre> +<h5>Overview:</h5> +<p> + This initializes the memory pointed to by <tt>tramp</tt> as a trampoline. +</p> +<h5>Arguments:</h5> +<p> + The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all + pointers. The <tt>tramp</tt> argument must point to a sufficiently large + and sufficiently aligned block of memory; this memory is written to by the + intrinsic. Currently LLVM provides no help in determining just how big and + aligned the memory needs to be. The <tt>func</tt> argument must hold a + function bitcast to an <tt>i8*</tt>. +</p> +<h5>Semantics:</h5> +<p> + The block of memory pointed to by <tt>tramp</tt> is filled with target + dependent code, turning it into a function. + The new function's signature is the same as that of <tt>func</tt> with + any arguments marked with the <tt>nest</tt> attribute removed. At most + one such <tt>nest</tt> argument is allowed, and it must be of pointer + type. Calling the new function is equivalent to calling <tt>func</tt> + with the same argument list, but with <tt>nval</tt> used for the missing + <tt>nest</tt> argument. +</p> +</div> + +<!-- _______________________________________________________________________ --> +<div class="doc_subsubsection"> + <a name="int_at">'<tt>llvm.adjust.trampoline</tt>' Intrinsic</a> +</div> +<div class="doc_text"> +<h5>Syntax:</h5> +<pre> +declare i8* @llvm.adjust.trampoline(i8* <tramp>) +</pre> +<h5>Overview:</h5> +<p> + This intrinsic returns a function pointer suitable for executing + the trampoline code pointed to by <tt>tramp</tt>. +</p> +<h5>Arguments:</h5> +<p> + The <tt>llvm.adjust.trampoline</tt> takes one argument, a pointer to a + trampoline initialized by the + <a href="#int_it">'<tt>llvm.init.trampoline</tt>' intrinsic</a>. +</p> +<h5>Semantics:</h5> +<p> + A function pointer that can be used to execute the trampoline code in + <tt>tramp</tt> is returned. The returned value should be bitcast to an + <a href="#int_trampoline">appropriate function pointer type</a> + before being called. +</p> +</div> + +<!-- ======================================================================= --> +<div class="doc_subsection"> <a name="int_general">General Intrinsics</a> </div> |
