similar to: [LLVMdev] CallGraphSCC passes and function passes

I don't mean to be a pain, but I was thinking about this a bit more. Does gcc ignore the const keyword? If not, why has LLVM chosen to deviate from gcc with respect to the const keyword? If so, then why do we bother using const in LLVM API code? I'm just curious and wanted to understand the thinking behind not preserving const. Thanks, Ryan Chris Lattner wrote: > This property

I don't follow what you mean - gcc doesn't ignore const and llvm doesn't deviate from gcc nor from the relevant language standards. Note that if you declare a global as const that we do capture this in the ir - what specifically do you want? Please provide an example. -Chris http://nondot.org/sabre http://llvm.org On Aug 14, 2007, at 11:58 PM, "Ryan M. Lefever"

This property isn't preserved on the llvm ir, because const can always be cast away. If you want mod information, then I suggest using the aliasanalysis interface to get mod ref info for a call. -Chris http://nondot.org/sabre http://llvm.org On Aug 8, 2007, at 12:07 AM, "Ryan M. Lefever" <lefever at crhc.uiuc.edu> wrote: > How is c's const keyword translated

Hi, I think I found a bug. I don't know if it's in upstream gcc or llvm-gcc4. int func() { const int *arr; arr[0] = 1; } $ llvm-gcc main.c -c; echo $? 0 $ gcc main.c -c main.c: In function 'func': main.c:4: error: assignment of read-only location The difference disappears when arr[0] is replaced by *arr. (I tried the above with gcc 4.1.2, 3.4.6, 4.0.3. (I don't

This certainly doesn't occur in gcc mainline. In fact, I improved the error message, and added a error test to gcc just yesterday. On 8/9/07, Chris Lattner <sabre at nondot.org> wrote: > On Wed, 8 Aug 2007, Nikhil A. Patil wrote: > > I think I found a bug. I don't know if it's in upstream gcc or llvm-gcc4. > > Looks like a bug, please file a bugzilla entry. >

How is c's const keyword translated when compiling c into llvm bytecode. I'm specifically interested in const pointer function arguments. Consider a function declared as follows in c: void f(const int* arg); When I examine f in llvm bytecode, how can I tell that arg is a pointer, whose contents can only be read, not written. Regards, Ryan

On Wed, 8 Aug 2007, Nikhil A. Patil wrote: > I think I found a bug. I don't know if it's in upstream gcc or llvm-gcc4. Looks like a bug, please file a bugzilla entry. -Chris > int func() > { > const int *arr; > arr[0] = 1; > } > > $ llvm-gcc main.c -c; echo $? > 0 > > $ gcc main.c -c > main.c: In function 'func': > main.c:4: error:

On Thu, 9 Aug 2007, Daniel Berlin wrote: > This certainly doesn't occur in gcc mainline. > In fact, I improved the error message, and added a error test to gcc > just yesterday. Yep, clang reports: t.c:4:12: error: read-only variable is not assignable arr[0] = 1; ~~~~~~ ^ 1 diagnostic generated. so this is specific to llvm-gcc somehow. -Chris > On 8/9/07, Chris

I think that we are talking about two different things. I understand that in order to use LLVM classes you must either qualify them with the llvm namespace or use the statement "using namespace llvm;" What I'm saying is that it has been my experience that when a pass Y depends on another pass X, i.e, Y is a required analysis of X, then Y must be defined within the llvm

I printed the call graph as you suggested. The bugpoint bytecode that I sent below prints the following call graph: Indirect call node / | | \ / | | \ V | V V execute | prog_char clear_func | | V V push_constant | V Node0x8d7b370 i.e., Indirect call node -> execute

So, am I correct that the implication of what you're saying is that if pass X requires pass Y, then pass Y does not necessarily run to completion on every component of a program, before pass X runs. Furthermore, if those passes X and Y are both function passes, then when pass X runs on function F, the last function Y will have run on is function F. Chris Lattner wrote: > On Fri, 22

Chris, I'm a little confused. I am experiencing a crash when compiling the llvm-gcc frontend. According to the bugpoint documentation, bugpoint is used to debug "optimizer crashes, miscompilations by optimizers, or bad native code generation," which seems like it implies that the frontend compiles. Also, the http://llvm.org/docs/HowToSubmitABug.html documentation seems to

Since Data Structure alias analysis inherits from ModulePass rather than FunctionPass, does that mean that it performs interprocedural alias analysis? Further, if I compare pointers from two different functions, will I sometimes get a NoAlias response. Regards, Ryan -- Ryan M. Lefever [http://www.ews.uiuc.edu/~lefever]

In the instructions for writing LLVM passes, it says "[c]urrently it is illegal for a ModulePass to require a FunctionPass. This is because there is only one instance of the FunctionPass object ever created, thus nowhere to store information for all of the functions in the program at the same time." I'm a little confused by that. It was my understanding that if pass X required

Does llvm-gcc support the -fPIC option? I am using LLVM on both 32 bit linux and 64 bit linux, if that matters. Regards, Ryan -- Ryan M. Lefever [http://www.crhc.uiuc.edu/~lefever/index.html]

I assume that when -O3 (or O2 or O1) is passed to llvm-gcc, then it utilizes opt. How do I determine what passes opt runs? How do I determine what external tools (and arguments) llvm-gcc is invoking? Regards, Ryan

Can I specify passes that I want run directly to llvm-gcc? I don't want all of -O3, for example. I tried llvm-gcc -raiseallocs ..., but that didn't work. I also tried running cc1 directly and it didn't take -raiseallocs as a parameter either. Duncan Sands wrote: > On Tuesday 28 April 2009 04:02:47 am Ryan M. Lefever wrote: >> I assume that when -O3 (or O2 or O1) is

On Sun, 3 Dec 2006, Ryan M. Lefever wrote: > I am working on a transform that uses an scc_iterator on a program's > CallGraph. However, I am running into a problem in which not all > callees are being processed before callers, leading me to believe there > might be a bug. In particular, this is happening in a case where a > callee is a function pointer. I ran bugpoint and

I need to create a cast instruction that casts an sbyte* to another pointer type. Previously I was using the CastInst::createInferredCast() function to do that; however, that function has been removed. Which of the create() functions from CastInst should I use to do that? It seems like the obdvious answer should be createPointerCast(). However, the documentation for createPointerCast

I am writing a pass where I need to make a function deceleration for printf. Below is the code I'm trying to use. ----- bool MyPass::runOnModule(Module &m) { vector<const Type*> args; args.push_back(PointerType::get(Type::SByteTy)); Function* f = m.getOrInsertFunction("printf", FunctionType::get(Type::IntTy, args, true)); ----- When I insert a call