search for: inttoptrs

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

Hi, I am observing some incorrect behavior in basicaa, wherein two pointers that basicaa should determine to be MustAlias are ending up NoAlias - the other extreme :( I am blaming this on basicaa not handling inttoptr. Here is the relevant IR snippet. -------------------- %sunkaddr36 = ptrtoint %struct.BitParams* %bs to i32 %sunkaddr37 = add i32 %sunkaddr36, 16 %sunkaddr38 = inttoptr i32

LLVM 2.7's ScalarEvolution.cpp has this scary comment: // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can // lead to pointer expressions which cannot safely be expanded to GEPs, // because ScalarEvolution doesn't respect the GEP aliasing rules when // simplifying integer expressions. I think I understand what the comment is saying. If a GEP has

Hi again. I have a complex type system in my custom language that isn't easily representable as LLVM IR types, so I figured I could mostly get along with treating my types as i8* and doing the appropriate bitcasts and inttoptr instructions, and doing pointer arithmetic myself (by casting the pointers to ints, adding the appropriate byte offsets, and then casting back to pointers). However,

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." >

On Wed, Apr 20, 2011 at 12:20 PM, Eli Friedman <eli.friedman at gmail.com> wrote: > 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

RFC: GEP as canonical form for pointer addressing I would like to propose that we designate GEPs as the canonical form for pointer addressing in LLVM IR before CodeGenPrepare. Corollaries 1) It is legal for an optimizer to convert inttoptr+arithmetic+inttoptr sequences to GEPs, but not vice versa. 2) Input IR which does not contain inttoptr instructions will never contain inttoptr

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 Wed, Apr 20, 2011 at 10:21 AM, Jianzhou Zhao <jianzhou at seas.upenn.edu> wrote: > On Wed, Apr 20, 2011 at 12:20 PM, Eli Friedman <eli.friedman at gmail.com> wrote: >> 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

Thank you for the hint. I adjusted the code and it works: The code after replacing inttoptr with getelementptr: define { i32, i32, i8* } @test(i32 %foo, i32 %bar, i8* %sp) { entry: ; push foo (On "stack") %sp_1 = getelementptr i8, i8* %sp, i32 -4 %sp_1_ptr = bitcast i8* %sp_1 to i32* store i32 %foo, i32* %sp_1_ptr, align 4 ; push bar %sp_2 = getelementptr i8, i8* %sp_1,

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 =

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

...y 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 inttoptrs, meaning that 95.4% >> of them are generated by LLVM passes. >> >> This trend is similar in ptrtoint instruction as well. When compiling >> SPEC 2017 >> with -O0, there are 23,208 ptrtoint instructions, but among them 22,016 >> (94.8%) >> are generated by C...

...y 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 inttoptrs, meaning that 95.4% of them are generated by LLVM passes. This trend is similar in ptrtoint instruction as well. When compiling SPEC 2017 with -O0, there are 23,208 ptrtoint instructions, but among them 22,016 (94.8%) are generated by Clang frontend to represent pointer subtraction. They aren'...

On Wed, Apr 20, 2011 at 2:11 PM, Eli Friedman <eli.friedman at gmail.com> wrote: > On Wed, Apr 20, 2011 at 10:21 AM, Jianzhou Zhao <jianzhou at seas.upenn.edu> wrote: >> On Wed, Apr 20, 2011 at 12:20 PM, Eli Friedman <eli.friedman at gmail.com> wrote: >>> On Wed, Apr 20, 2011 at 8:08 AM, Jianzhou Zhao <jianzhou at seas.upenn.edu> wrote: >>>> I

Hi again, So I finally gave up on trying to get through the converting (x86' push pop mov add) because it deals a lot with crazy pointer arithmetics and sonce inttoptr and ptrtoint doesn't provide any alias analysis information. Daniel, you said it doesn't make much sense to provide it but in my cases it is actually very much needed, you didn't say it wasn't possible to

On Thu, Nov 8, 2012 at 6:53 PM, Pranav Bhandarkar <pranavb at codeaurora.org> wrote: > Hi, > > I am observing some incorrect behavior in basicaa, wherein two pointers that > basicaa should determine to be MustAlias are ending up NoAlias - the other > extreme :( > I am blaming this on basicaa not handling inttoptr. Here is the relevant IR > snippet. >

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." So this means the conversion discussed here is still safe in terms of memory safety, but its meaning after conversion

On Sep 9, 2010, at 1:48 PM, David Greene wrote: > LLVM 2.7's ScalarEvolution.cpp has this scary comment: > > // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can > // lead to pointer expressions which cannot safely be expanded to GEPs, > // because ScalarEvolution doesn't respect the GEP aliasing rules when > // simplifying integer

Hello, I am trying to emulate the "stack" as like on x86 when using push/pop so afterwards I can use LLVM's optimizer passes to simplify (reduce junk) the code. The LLVM IR code: define { i32, i32, i32 } @test(i32 %foo, i32 %bar, i32 %sp) { ; push foo (On "stack") %sp_1 = sub i32 %sp, 4 %sp_1_ptr = inttoptr i32 %sp_1 to i32* store i32 %foo, i32* %sp_1_ptr, align