search for: setdoesnotaccessmemory

...output). I was wondering if using the setOnlyReadsMemory method on the native function objects could help LLVM generate optimized code (because it would then know the function has no side effects), and say, eliminating redundant calls to the same accessor function. Also, I would like to know what setDoesNotAccessMemory means exactly. Is it used to mean that a function accesses no memory (neither read nor write) outside of its stack frame? I'm just puzzled as to the meaning of the flags these two methods set on a function, and whether they are useful or not for LLVM to perform optimizations (and if they are, w...

...mory method on the native function objects could help LLVM >> generate optimized code (because it would then know the function has no >> side >> effects), and say, eliminating redundant calls to the same accessor >> function. >> >> Also, I would like to know what setDoesNotAccessMemory means exactly. Is >> it >> used to mean that a function accesses no memory (neither read nor write) >> outside of its stack frame? I'm just puzzled as to the meaning of the >> flags >> these two methods set on a function, and whether they are useful or not >>...

...using the > setOnlyReadsMemory method on the native function objects could help LLVM > generate optimized code (because it would then know the function has no side > effects), and say, eliminating redundant calls to the same accessor > function. > > Also, I would like to know what setDoesNotAccessMemory means exactly. Is it > used to mean that a function accesses no memory (neither read nor write) > outside of its stack frame? I'm just puzzled as to the meaning of the flags > these two methods set on a function, and whether they are useful or not for > LLVM to perform optimizations...

...functions as built-ins and determine the expected answer when the arguments are constants, and elides the tests in the simple example below - all this is good, and when I use ‘-fno-builtin’ it stops correctly disabled this optimisation. I modified my sources to force ‘readnone’ and even tried ‘setDoesNotAccessMemory()’ on the math functions, but this still results in one call occurring and the code generated is effectively: (void)exp(1.0); return 0; This is better, but still not as optimal as it was in v3.8. With this change, compiling with ‘-fmath-errno’ reverts to inserting two calls. While cal...

A little while ago I asked a question on CFE-Dev about a change in the behaviour of programs using the ISO C math functions, although that question should have been put to LLVM-Dev. But I got excellent clarification of the problem anyway. However, since then I have been trying to adapt our out-of-tree implementation to get the previous behaviour. The problem is that something like: #include

On Wednesday 01 April 2009 20:01:09 Dan Gohman wrote: > On Apr 1, 2009, at 7:25 AM, Torvald Riegel wrote: > > On Wednesday 25 March 2009, Luke Dalessandro wrote: > >> You could encode this information as simple library function calls > >> and > >> then find them again in the generated LLVM IR. The client then just > >> needs a header declaring the

----- Original Message ----- > From: "James Molloy via llvm-dev" <llvm-dev at lists.llvm.org> > To: "Vaivaswatha Nagaraj" <vn at compilertree.com> > Cc: "LLVM Dev" <llvm-dev at lists.llvm.org> > Sent: Thursday, December 3, 2015 4:41:46 AM > Subject: Re: [llvm-dev] Function attributes for LibFunc and its impact on GlobalsAA > >