similar to: how to allocate consecutive register?

Hi, I think I discovered a major armv7 optimization bug in Clang. I create a simple test case which exhibits the issue. When you compile the attached file for armv7 with optimizations turned on (O2, O3 or Os), the binary generated led to a crash. The issue can't be reproduced when using GCC 4.2. It can't be reproduced with Clang when the optimization is turned off (O0). This issue can be

The problem is in your code, not the compiler. You're casting an unaligned char* to an int*, even though an int* pointer must be 4-byte aligned in every ARM ABI that I've ever seen. On Jan 23, 2012, at 6:14 AM, Alexandre Colucci wrote: > Hi, > > I think I discovered a major armv7 optimization bug in Clang. I create a simple test case which exhibits the issue. > When you

In practice all Apple hardwares support misaligned accesses for single-register loads and stores. If a pointer is not aligned, LLVM should not use the double-register loads and stores. It should keep the two single-register loads instead of trying to optimize them as one unsupported double-register load. Note that this code compiled with GCC 4.2 runs perfectly whereas LLVM will produce a binary

r175088 attempted to fix gcc inline asm compatibility with 64-bit operands by forcing these into even/odd register pairs the same way gcc always allocates such values. While the fix appears to work as such, it is not always activated when required. The patch makes the assumption that any inline asm statement relying on the even/odd allocation will make use of the %Hn syntax to reference the high

On 13 March 2013 13:43, Måns Rullgård <mans at mansr.com> wrote: > One possible fix, which I have tested, is to look for the specific > instructions requiring such a pair (LDRD/STRD and LDREXD/STREXD) in > addition to the 'H' modifier. However, there are probably other > creative ways in which inline asm might rely on the specific pairing. > Hi Mans, Either that

Hi Renato, It seems to me that LLVM doesn’t parse the inline asm body. It just checks the constraints, (ie. Input/output interface). During ASM writing, it then binding those constraints to placeholders like %0, %1. So it a constraint is a 64-integer type, it *probably* needs paired GPR. Weiming Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The

> -----Original Message----- > From: meinersbur at googlemail.com [mailto:meinersbur at googlemail.com] On > Behalf Of Michael Kruse > Sent: Wednesday, October 18, 2017 1:18 PM > To: Song, Ruiling <ruiling.song at intel.com> > Cc: Michael Kruse <llvm at meinersbur.de>; llvm-dev at lists.llvm.org > Subject: Re: Possible bug of Alias Analysis? > > 2017-10-18

> On Dec 21, 2016, at 10:26, Ruiling Song <ruiling.song83 at gmail.com> wrote: > > > > 2016-12-20 22:14 GMT+08:00 Tom Stellard <tom at stellard.net <mailto:tom at stellard.net>>: > > > > On Tue, Dec 20, 2016 at 11:00:09AM +0800, Ruiling Song wrote: > > > Hi, > > > > > > I am working on a new LLVM target for Intel GPU, which

On Wed, Dec 21, 2016 at 10:31:57AM -0500, Matt Arsenault wrote: > > > On Dec 21, 2016, at 10:26, Ruiling Song <ruiling.song83 at gmail.com> wrote: > > > > > > > > 2016-12-20 22:14 GMT+08:00 Tom Stellard <tom at stellard.net <mailto:tom at stellard.net>>: > > > > > > On Tue, Dec 20, 2016 at 11:00:09AM +0800, Ruiling Song

Yes, the arch is just as you said, something like AMD GPU, but Intel GPU don't have separate register file for 'scalar/vector'. In fact my idea of defining the register tuples was borrowed from SIRegisterInfo.td in AMD GPU. But seems that AMD GPU mainly support i32/i64 register type, while Intel GPU also support byte/short register type. So I have to start defining the registers from

> -----Original Message----- > From: meinersbur at googlemail.com [mailto:meinersbur at googlemail.com] On > Behalf Of Michael Kruse > Sent: Tuesday, October 17, 2017 3:26 PM > To: Song, Ruiling <ruiling.song at intel.com> > Cc: llvm at meinersbur.de; llvm-dev at lists.llvm.org > Subject: Re: Possible bug of Alias Analysis? > > 2017-10-17 8:45 GMT+02:00 Song,

> On Apr 2, 2015, at 2:07 PM, Tom Stellard <tom at stellard.net> wrote: > > On Thu, Apr 02, 2015 at 01:35:55PM -0700, Pete Cooper wrote: >> Hi James, Jim >> >> If you *really* want this to work in selection DAG then there is a solution, but its not pretty. >> >> First make i64 not be legal. Then, assuming the regclass you gave has some subregs, you

2016-12-20 22:14 GMT+08:00 Tom Stellard <tom at stellard.net>: > > On Tue, Dec 20, 2016 at 11:00:09AM +0800, Ruiling Song wrote: > > Hi, > > > > I am working on a new LLVM target for Intel GPU, which also has same kind > > of scalar/vector register classes used in AMDGPU target. Like for a i32 > > virtual register, it will be held in scalar register if its

No one is arguing that there aren't ABI specs or LLVM design guidelines that say that unaligned accesses "should not", "could not" or "aren't guaranteed to" work, because it's besides the point. The point is that unaligned 32-bit loads and stores *work in practice* on every single ARM device Apple has ever manufactured. I'm not a hardware person, but

Some code in GVN.cpp: static Value *CoerceAvailableValueToLoadType(Value *StoredVal, Type *LoadedTy, Instruction *InsertPt, const DataLayout &DL) { .... // Convert vectors and fp to integer, which can be manipulated. if (!StoredValTy->isIntegerTy()) {

On Tue, Dec 20, 2016 at 11:00:09AM +0800, Ruiling Song wrote: > Hi, > > I am working on a new LLVM target for Intel GPU, which also has same kind > of scalar/vector register classes used in AMDGPU target. Like for a i32 > virtual register, it will be held in scalar register if its value is > uniform across a wavefront/warp, otherwise it will be in a vector register. > Does

On Mar 13, 2013, at 10:15 AM, Weiming Zhao <weimingz at codeaurora.org> wrote: > Hi Renato, > > It seems to me that LLVM doesn’t parse the inline asm body. It just checks the constraints, (ie. Input/output interface). During ASM writing, it then binding those constraints to placeholders like %0, %1. This is correct. > So it a constraint is a 64-integer type, it *probably*

> Note that this code compiled with GCC 4.2 runs perfectly whereas LLVM will produce a binary that crashes: LLVM breaks existing source code. On this point: This is not uncommon - and the very nature of "Undefined Behaviour". This reason alone is not enough to justify a change to Clang. We/you would need to show that the behaviour is defined & Clang is violating that definition.

Is it just an optimization pass? Maybe I can cancel it somehow with a flag or by doing some code editing? Can you point me to which passes may do that? I'm working on editing a backend that can't work with anything larger than 32 bits. Does the legalize stage work on IR code? Maybe i can use that? On Jan 29, 2015 5:41 AM, Ruiling Song <ruiling.song83 at gmail.com> wrote: LLVM

Hi Escha, Great to have your comment! Do you have any specific reason for not doing like this? I am not sure whether I understand your point correctly. For "just model one thread", do you mean "only considering ONE of the 8/16 working lanes that running in lock-step way"?? For my case, may be something like I only need to define r0~r127 as register for i32 register (each r#