similar to: [LLVMdev] Uninitialized variable - question

I think that the relevant part in C11 is section 6.2.6.1, which tells you that accessing a trap representation, _other than using a char type_, is undefined. Objects of automatic storage, which don't have an initializer are of indeterminate value, which either is an unspecified value or a trap representation. > What I found is that with -O2: > LLVM (trunk) prints both "a" and

On 11/24/2012 02:08 AM, Jakub Staszak wrote: > Hello, > > I was wondering about the case below. I tried to find any information in C standard, but I found nothing. > In this case, variable "i" is uninitialized, but it is the _same_ value passed as an argument, so only of "a" or "b" should be printed. > > What I found is that with -O2: > LLVM

On 24/11/2012, at 10:21 PM, Nick Lewycky wrote: > > Passing an uninitialized value as a function argument is undefined behaviour on the spot, regardless of what the callee does (even if it never references that argument). Cite reference? No? Then you're guessing ;) > > That aside, there is no way that 'i' has the same value, since it has no value. This is definitely

On 11/24/2012 04:14 AM, john skaller wrote: > > On 24/11/2012, at 10:21 PM, Nick Lewycky wrote: > >> >> Passing an uninitialized value as a function argument is undefined behaviour on the spot, regardless of what the callee does (even if it never references that argument). > > Cite reference? No? Then you're guessing ;) This is a rule in C++ that I'm not sure

On Aug 21, 2009, at 10:27 PM, Eli Friedman wrote: > On Fri, Aug 21, 2009 at 5:05 PM, Jakub Staszak<kuba at gcc.gnu.org> > wrote: >> >> On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: >> >>> On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> >>> wrote: >>>> >>>> On Aug 21, 2009, at 8:46 PM, Eli

On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: > On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> > wrote: >> >> On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: >> >>> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> >>> wrote: >>>> >>>> On Aug 21, 2009, at 7:31 PM, Eli

On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: > On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> > wrote: >> >> On Aug 21, 2009, at 7:31 PM, Eli Friedman wrote: >> >>> On Fri, Aug 21, 2009 at 2:06 PM, Jakub Staszak<kuba at gcc.gnu.org> >>> wrote: >>>> >>>> Hello, >>>>

Hello, This patch fixes PR4174. Two test-cases included: original one from bugzilla and a little bit complicated made be myself. It seems that LoopIndexSplit doesn't handle some cases, I'll try to send some patch this week. Regards -- Jakub Staszak -------------- next part -------------- A non-text attachment was scrubbed... Name: pr4174.patch Type: application/octet-stream Size:

On Fri, Aug 21, 2009 at 5:47 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: > > On Aug 21, 2009, at 10:27 PM, Eli Friedman wrote: > >> On Fri, Aug 21, 2009 at 5:05 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: >>> >>> On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: >>> >>>> On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at

On Fri, Aug 21, 2009 at 5:05 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: > > On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: > >> On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: >>> >>> On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: >>> >>>> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at

Adding LLVMdev, since this is intimately related to the optimization passes. > I think this is roughly because some function level optimisations are > worse than O(N) in the number of instructions. Please profile this and mail llvmdev regarding passes with significantly superlinear behavior (e.g. O(n^2)). My understanding is that these kinds of algorithmic problems are generally considered

On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: > > On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: > >> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: >>> >>> On Aug 21, 2009, at 7:31 PM, Eli Friedman wrote: >>> >>>> On Fri, Aug 21, 2009 at 2:06 PM, Jakub Staszak<kuba at

On 23/11/2012, at 5:46 PM, Sean Silva wrote: > Adding LLVMdev, since this is intimately related to the optimization passes. > >> I think this is roughly because some function level optimisations are >> worse than O(N) in the number of instructions. > > Please profile this and mail llvmdev regarding passes with > significantly superlinear behavior (e.g. O(n^2)). My

Hello, This patch fixes pr5373, testcase of course attached. -Jakub -------------- next part -------------- A non-text attachment was scrubbed... Name: 5373.patch Type: application/octet-stream Size: 1540 bytes Desc: not available URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20091123/3f8fe7b3/attachment.obj>

Hi, Because of this "return true" not every block was visited and only one ExitBB was found (instead of two). Thus, loop was optimized as a trivial one, which was wrong. -Jakub On Nov 24, 2009, at 2:28 PM, Dan Gohman wrote: > Hello, > > I haven't studied this in detail, but at a first look this makes the > code inconsistent with the associated comments. Why

On Wed, Jun 21, 2017 at 05:25:04PM -0700, Mehdi AMINI via llvm-dev wrote: > Hi Kuba, > > Try: > > __attribute__(optnone) > > See > https://clang.llvm.org/docs/AttributeReference.html#optnone-clang-optnone Actually, it should be enough to use: __attribute__((noinline)) void please_do_not_optimize_me_away(int arg1, void *arg2) { asm

Hello, Simply removing that "return true" causes the code to search blocks outside of loops for side effects. That's not what the code is supposed to do. Dan On Nov 27, 2009, at 3:01 AM, Jakub Staszak wrote: > Hi, > > Because of this "return true" not every block was visited and only one ExitBB was found (instead of two). Thus, loop was optimized as a trivial

Hello, Yeah, sorry, you are right. My new idea is that only one ExitBB is found because Header ("for.body") is already marked as visited. I'm pretty sure that someone had a good reason to do this that way, but I can't find it out :) Dan, can you look at this patch? Thanks -Jakub -------------- next part -------------- A non-text attachment was scrubbed... Name:

Hello, This patch fixes PR7052. Regards -- Jakub Staszak -------------- next part -------------- A non-text attachment was scrubbed... Name: pr7052.patch Type: application/octet-stream Size: 3223 bytes Desc: not available URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20100508/4648de5a/attachment.obj>

Hi llvm-dev, I have a C function: __attribute__((__visibility__("default"))) __attribute__((used)) __attribute__((noinline)) void please_do_not_optimize_me_away(int arg1, void *arg2) { asm volatile("" :::); } (the purpose is that this function will be used dynamically at runtime, perhaps by interposing the function, or via the debugger) I really thought this will not get