similar to: Redundant ptrtoint/inttoptr instructions

My general feeling is this: No optimizations should be creating int2ptr/ptr2int. We really need to fix them all. They should use pointer casts and i8* GEPs. This has, unfortunately, been a problem for a long time. As Johannes says, optimizing int2ptr/ptr2int is very tricky. In part, becaue all dependencies, including implicit control dependencies, end up being part of the resulting aliasing

Hi, I try to understand why llvm can't optimize this small piece of code. My expectation is that the IR will be optimized to a " ret i64 2101545. But somehow the alias analysis fails when the pointer is casted to an integer value, so the dead code eliminator can't optimize it away. Could someone explain to me why this is failing and if there is a solution for that ? I can trick the

On 06/20/2017 03:26 AM, Hal Finkel wrote: > Hi, Adrien, Hello Hal! Thanks for your answer! > Thanks for reporting this. I recommend that you file a bug report at > https://bugs.llvm.org/ Will do! > Whenever I see reports of missed optimization opportunities in the face > of ptrtoint/inttoptr, my first question is: why are these instructions > present in the first place? At

Hello Chandler, > First and foremost - how do you address correctness issues here? Because the subtraction `A - B` can escape/capture more things. Specifically, if one of `A` or `B` is escaped/captured, the > subtraction can be used to escape or capture the other pointer. So *some* of the conservative treatment is necessary. What is the plan to update all the analyses to remain correct?

Hello all, This is a proposal for reducing # of ptrtoint/inttoptr casts which are not written by programmers but rather generated by LLVM passes. Currently the majority of ptrtoint/inttoptr casts are generated by LLVM; when compiling SPEC 2017 with LLVM r348082 (Dec 2 2018) with -O3, the output IR contains 22,771 inttoptr instructions. However, when compiling it with -O0, there are only 1048

Hello Chandler, > ``` > void f(int *arr1, int *arr2, int length) { > intptr_t rel_offset = arr2 - arr1; > int *arr1_end = arr1 + length; > for (int *p = arr1; p < arr1_end; p += sizeof(int)) { > do_something(p, p + rel_offset); > } > } > ``` > > For example, a common loop optimization technique is something like the following in *pseudocode* (note

Hello all, There is a missing vectorization opportunity issue with clang 4.0 with the file attached. Indeed, when compiled with -O2, the "op_distance" function get vectorized, but not the "op" one. For information, this test case has been reduced from a file generated by the Pythran compiler (https://github.com/serge-sans-paille/pythran). If we take a look at the generated

Consider the two functions bellow: define i8* @f(i8* %A) { %pti = ptrtoint i8* %A to i64 %add = add i64 %pti, 5 %itp = inttoptr i64 %add to i8* ret i8* %itp} define i8* @g(i8* %A) { %gep = getelementptr i8* %A, i64 5 ret i8* %gep} What, if anything, prevents us from canonicalizing @f to @g?I've heard that this might be in violation of http://llvm.org/docs/LangRef.html#pointeraliasing

On 09/08/2014 04:22 PM, Dan Gohman wrote: > An object can be allocated at virtual address 5 through extra-VM means > (eg. mmap), and then one can (creatively) interpret the return value > of @f as being associated with whatever %A was associated with *and* > 5. The return value of @g can only be associated with exactly the same > set that %A was associated with. Consequently,

----- Original Message ----- > From: "Bjarke Roune" <broune at google.com> > To: "Hal Finkel" <hfinkel at anl.gov> > Cc: llvmdev at cs.uiuc.edu, "Jingyue Wu" <jingyue at google.com> > Sent: Wednesday, July 1, 2015 2:27:59 PM > Subject: Re: [LLVMdev] Deriving undefined behavior from nsw/inbounds/poison for scalar evolution > >

On Mon, Apr 4, 2011 at 5:02 PM, Arushi Aggarwal <arushi987 at gmail.com> wrote: > > >> Hi, >> Is it correct to convert, >>   %196 = load i32* %195, align 8                  ; <i32> [#uses=1] >>   %197 = zext i32 %196 to i64                     ; <i64> [#uses=1] >>   %198 = ptrtoint i8* %193 to i64                 ; <i64> [#uses=1]

This code is generated for va_arg. %6 = getelementptr inbounds %struct.__va_list_tag* %5, i32 0, i32 3 ; <i8**> [#uses=1] %7 = load i8** %6, align 8 ; <i8*> [#uses=1] %8 = getelementptr inbounds [1 x %struct.__va_list_tag]* %ap, i64 0, i64 0 ; <%struct.__va_list_tag*> [#uses=1] %9 = getelementptr inbounds %struct.__va_list_tag* %8, i32 0, i32 0 ;

On Mon, Apr 4, 2011 at 7:10 AM, John Criswell <criswell at illinois.edu> wrote: > On 4/4/2011 6:45 PM, Eli Friedman wrote: >> >> On Mon, Apr 4, 2011 at 5:02 PM, Arushi Aggarwal<arushi987 at gmail.com> >>  wrote: >>> >>>> Hi, >>>> Is it correct to convert, >>>>   %196 = load i32* %195, align 8                

On Mon, Sep 8, 2014 at 4:22 PM, Dan Gohman <dan433584 at gmail.com> wrote: > It looks a little silly to say this in the case of the integer constant 5, > and there are some semantic gray areas around extra-VM allocation, but the > same thing happens if the add were adding a dynamic integer value, and then > it's difficult to find a way to separate that case from the constant

On 4/4/2011 6:45 PM, Eli Friedman wrote: > On Mon, Apr 4, 2011 at 5:02 PM, Arushi Aggarwal<arushi987 at gmail.com> wrote: >> >>> Hi, >>> Is it correct to convert, >>> %196 = load i32* %195, align 8 ;<i32> [#uses=1] >>> %197 = zext i32 %196 to i64 ;<i64> [#uses=1] >>> %198 =

Hi, Is it correct to convert, %196 = load i32* %195, align 8 ; <i32> [#uses=1] %197 = zext i32 %196 to i64 ; <i64> [#uses=1] %198 = ptrtoint i8* %193 to i64 ; <i64> [#uses=1] %199 = add i64 %198, %197 ; <i64> [#uses=1] %200 = inttoptr i64 %199 to i8* ; <i8*>

Hi guys! I have to compute something and i don't know what i'm doing wrong. my code is a bit complex, but imagine that is something like this: a = c(1,2,3,4) ia = length(a) x = seq(1,100,length=0.1) ib = length(x) int1 = numeric(ib) b = numeric(ib) for(j in 1:ia) { H = function(x) {sin(x + a[j])} for(i in 1:ib) { int = integrate(H, lower = 0, upper

Hello! I''ve put some questions on this list some weeks ago and I''ve got good answers. Thank you! Now I''ve finished my (beautyful) script and I ran it on my router... About my script: It routes packages based on their destination on the Internet. I have about 1650 preffered destination networks listed in some file. The script read this file and marks every package for

On Wed, Apr 20, 2011 at 8:08 AM, Jianzhou Zhao <jianzhou at seas.upenn.edu> wrote: > I have a question about when we should apply these pointer aliasing > rules. Do the rules tell us when a load/store is safe? > "Any memory access must be done through a pointer value associated > with an address range of the memory access, otherwise the behavior is > undefined." >

Hi All, I'm working on a project converting Dart to llvm. Dart uses a relocating GC but additionally uses pointer tagging. The first bit of a pointer is a tag. For integers a '0' bit is used and for pointers to objects a '1' bit is used. V8 apparently uses a similar technique. Generated code may need to check which bit is used when this information isn't statically known.