search for: zextloads

Hi, For my research, I need to reshape the current ARM backend to support armv2a. Zero-extend half word load (ldrh) is not supported by armv2a, so I need to make the code generation to not generate ldrh instructions. I want to replace all those instances with a 32-bit load (ldr) and then and the result with 0xffff to mask out the upper bits. These are the modifications that I have made to

I'm curious about this code in ReduceLoadWidth (and in DAGCombiner in general): if (LegalOperations && !TLI.isLoadExtLegal(ExtType, ExtVT)) return SDValue <http://llvm.org/docs/doxygen/html/classllvm_1_1SDValue.html>(); LegalOperations is false for the first pre-legalize pass and true for the post-legalize pass. The first pass is target-independent yes? So that makes sense.

On Aug 18, 2010, at 9:56 AM, Chris Lattner wrote: > Some things to consider: When the input to the zext is spilled, the reload can be folded into the zext on almost all targets, making the zext free. When the zext *isn't* folded into a load, what you're really looking for is a code placement pass which tries to put the zexts in non-redundant (and non-partially redundant) places. That

> -----Original Message----- > From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] > On Behalf Of Fabian Scheler > Sent: Wednesday, August 15, 2012 9:12 AM > To: LLVM Developers Mailing List > Subject: [LLVMdev] More Back-End Porting Troubles > > Hi LLVM-Folks, > > as mentioned in an earlier post >

Hi, The target I am working on does not support i8 loading: it supports only 32 bit aligned loads. I had to custom lower i8 load so that only i32 loads are generated. My issue is the following: In a very specific case, the lowering stage generates the following pattern where the load is a i32 load: (and (load x), 255) This pattern is somehow converted by the DAG combiner back to: (zextload x,

...lt;8 x i8> %0 to <8 x i16> turning into: pmovzxbw (%rsi), %xmm0 pand <0xff,0xff,...>, %xmm0, %xmm0 v8i8 isn't legal, so the load became an anyext load from v8i8 to v8i16, with the pand masking out the unwanted/zero bits. In that example, if you declare zextloads from v8i8 legal, and add the simple corresponding pattern, the pand isn't generated anymore, as expected. So, unless I'm missing something, shouldn't we declare them legal? Insights much appreciated, thanks! - Ahmed

1) It's crashing because LD1 is produced due to LegalOperations=false in pre-legalize pass. Then Legalization does not know how to handle it so it asserts on a default case. I don't know if it's a reasonable expectation or not but we do not have support for it. I have not tried overriding shouldReduceLoadWidth. 2) I see, that makes sense to some degree, I'm curious if you can

Hi, first of all: thanks for your kind, very helpful and unbelievable fast response! >> as mentioned in an earlier post >> (http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-July/051677.html) I >> am currently working on a Back-End for the TriCore processor. >> Currently, I am struggling as LLVM could not select zext and load, for >> instance, so some of the testcases

Hi All, I'm writing a backend for a target which only supports 4-byte, 4-byte-aligned loads and stores. I custom-lower all {*EXT}LOAD and STORE nodes in TargetISelLowering.cpp to take advantage of all alignment information available to the backend, rather than treat each load and store conservatively, which takes O(10) instructions. My target's allowsUnalignedMemoryOperations()

On Aug 18, 2010, at 11:13 AM, Jakob Stoklund Olesen wrote: > > On Aug 18, 2010, at 9:56 AM, Chris Lattner wrote: > >> Some things to consider: When the input to the zext is spilled, the reload can be folded into the zext on almost all targets, making the zext free. When the zext *isn't* folded into a load, what you're really looking for is a code placement pass which

> On Nov 13, 2017, at 11:53 AM, Vedant Kumar via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi Amara, > >> On Nov 10, 2017, at 9:12 AM, Amara Emerson via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: >> >> Hi everyone, >> >> This RFC concerns the design and architecture of a generic machine

On Mon, Jul 18, 2011 at 6:35 PM, Damien Vincent <damien.llvm at gmail.com> wrote: > >   Hi, > > The target I am working on does not support i8 loading: it supports only 32 > bit aligned loads. > I had to custom lower i8 load so that only i32 loads are generated. > > My issue is the following: > In a very specific case, the lowering stage generates the following

On Aug 18, 2010, at 11:22 AM, Chris Lattner wrote: > > On Aug 18, 2010, at 11:13 AM, Jakob Stoklund Olesen wrote: > >> >> On Aug 18, 2010, at 9:56 AM, Chris Lattner wrote: >> >>> Some things to consider: When the input to the zext is spilled, the reload can be folded into the zext on almost all targets, making the zext free. When the zext *isn't*

On 7/19/10 10:36 AM, Duncan Sands wrote: > Hi JP, > > >> DAGCombiner::ReduceLoadWidth() does the following: >> /// ReduceLoadWidth - If the result of a wider load is shifted to right of N >> /// bits and then truncated to a narrower type and where N is a multiple >> /// of number of bits of the narrower type, transform it to a narrower load >> /// from

Hi LLVM-Folks, as mentioned in an earlier post (http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-July/051677.html) I am currently working on a Back-End for the TriCore processor. Currently, I am struggling as LLVM could not select zext and load, for instance, so some of the testcases in test/CodeGen/Generic are not successfully compiled by my back-end. Furthermore, I am completely puzzled by the

On Sep 10, 2013, at 8:59 AM, Robert Lytton <robert at xmos.com> wrote: > Hi, > > A bit more information. > I believe my problem lies with the fact that the load is left as 'anyext from i8'. > On the XCore target we know this will become an 8bit zext load - as there is no 8bit sign extended load! > If BB#1 were to force the load to a "zext from i8" would

On Wed, Jul 27, 2011 at 2:28 PM, Matt Johnson <johnso87 at crhc.illinois.edu> wrote: > Hi All, >     I'm writing a backend for a target which only supports 4-byte, > 4-byte-aligned loads and stores.  I custom-lower all {*EXT}LOAD and > STORE nodes in TargetISelLowering.cpp to take advantage of all alignment > information available to the backend, rather than treat each

Thanks for the suggestions Vedant. Synthetic debug info is an interesting idea that sounds worthwhile. Could this be implemented as a “wrapper” pass that automatically decorates debug info before and after a specific pass run in opt (or pipeline of passes)? It might be useful to be able to easily enable this for a wide range of tests without having to manually modify each run line, perhaps as an

Hi Eli, On 07/27/2011 04:59 PM, Eli Friedman wrote: > On Wed, Jul 27, 2011 at 2:28 PM, Matt Johnson > <johnso87 at crhc.illinois.edu> wrote: >> Hi All, >> I'm writing a backend for a target which only supports 4-byte, >> 4-byte-aligned loads and stores. I custom-lower all {*EXT}LOAD and >> STORE nodes in TargetISelLowering.cpp to take advantage of

> -----Original Message----- > From: Fabian Scheler [mailto:fabian.scheler at gmail.com] > Sent: Thursday, August 16, 2012 4:58 AM > To: LLVM Developers Mailing List; Villmow, Micah > Cc: Stellard, Thomas; cameron.mcinally at nyu.edu > Subject: Re: [LLVMdev] More Back-End Porting Troubles > > Hi, > > first of all: thanks for your kind, very helpful and unbelievable