similar to: [LLVMdev] Problems with DAG Combiner

On 23/08/2009, at 18.42, Stripf, Timo wrote: > Hi all, > > i’m writing an back-end for a new research processor architecture > and have problems with the DAG Combiner. The processor architecture > supports i1 and i32 registers. 1-bit registers are mainly used as > comparison result but basic operations like OR are not possible > between i1 registers. So I wrote custom

Hi Jakob, I forget to mention that I'm working atm on the old 2.5 release code base and not on the svn. So I don't know if the problem still exists. I'm going to test it now. > The Blackfin DSP can do simple i1 operations with the CC flag and > status bits. Initially I also marked i1 as a legal type, but it caused > a lot of problems. Now I pretend that the CC register

On 24/08/2009, at 01.19, Stripf, Timo wrote: > > I had also a lot of problems to get the i1 operations working. E.g. > I had to override the getSetCCResultType to get is working and for > ADDE/ADDC the i1 target registers are hardcoded. What is your SetCCResultType now? Can you compile the CodeGen/Blackfin/basic-i1.ll test case? I never got that one working with legal i1. The

I converted now my back-end with legal i1 lowering to the 2.6 branch and my original problem with the DAG combiner didn't occur any more and seems to be fixed. setOperationAction(ISD::OR, MVT::i1, Promote) also works fine for logical operations. > What is your SetCCResultType now? I changed SetCCResultType to return MVT::i1 type. > Can you compile the CodeGen/Blackfin/basic-i1.ll

Hi all, The DAGCombiner pass actually runs even if the optimize level is set to None. This can result in incorrect debug information or unexpected stepping/debugging experience. Not to mention that having good stepping/debugging experience is the major reason to compile at /O0. I recently suggested a patch to disable one specific DAG combine at /O0 that broke stepping on a particular case

This code lives in DAGCombiner.cpp: ------------- // Turn 'store float 1.0, Ptr' -> 'store int 0x12345678, Ptr' if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(Value)) { // NOTE: If the original store is volatile, this transform must not increase // the number of stores. For example, on x86-32 an f64 can be stored in one // processor operation but

Duncan: DAGCombine is inserting an IllegalOperation after target-specific instruction legalization has occurred. I'm inserting the fabs and the bitconvert during instruction legalization; DAGCombine is converting the fabs/bitconvert to an 'and' on its second (third?) pass. -scooter On Jan 20, 2009, at 12:24 AM, Duncan Sands wrote: > On Tuesday 20 January 2009 07:52:37

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 address + N / num of bits of new type. If the result is to be /// extended, also fold the extension to form a

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 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 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 address + N / num of bits of new type. If the result is to be > /// extended,

Hello, In the combine 2 step (after legalization), in the DAGCombiner::visitBIT_CONVERT() method, the DAG combiner is replacing an FABS followed by a BIT_CONVERT, to a BIT_CONVERT followed by an AND 0x7FFFFFFFFFFFFFFF. Everything is 64 bit. On my target, FABS and BIT_CONVERT are legal in 64 bit, but AND in not legal in 64 bit (is declared custom). So the dag combiner is introducing illegal (not

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

On Thu, 13 Dec 2018 at 21:41, Friedman, Eli <efriedma at codeaurora.org> wrote: > > On 12/13/2018 6:25 AM, Alex Bradbury wrote: > > There's also likely to be cases where you want to calculate the demanded bits > > in order to determine if e.g. a W-suffixed instruction can be selected for > > `(somoeop (zexti32 GPR:$rs1), (zexti32 GPR:$rs2))`. This is easy to match

I got bit by this in LLVM 2.4 DagCombiner.cpp and it's still in trunk: SDValue DAGCombiner::visitSTORE(SDNode *N) { [...] // If this is a store of a bit convert, store the input value if the // resultant store does not need a higher alignment than the original. if (Value.getOpcode() == ISD::BIT_CONVERT && !ST->isTruncatingStore() && ST->isUnindexed()) {

Hi all, I have been looking at the way LLVM optimizes code before forwarding it to the backend I develop for my company and while building define i32 @test_extract_subreg_func(i32 %x, i32 %y) #0 { entry: %conv = zext i32 %x to i64 %conv1 = zext i32 %y to i64 %mul = mul nuw i64 %conv1, %conv %shr = lshr i64 %mul, 32 %xor = xor i64 %shr, %mul %conv2 = trunc i64 %xor to i32

Hi Ivan, On Tue, May 22, 2012 at 5:09 PM, Ivan Llopard <ivanllopard at gmail.com> wrote: > Hi Sebastian, > > On 22/05/2012 23:25, Sebastian Pop wrote: >> So my question is how do we specify that for most of the operations i8 >> should be promoted to i32 and that only a few logical operations are >> legal on i8? > > I think the combo

if (N0.getOpcode() == ISD::SETCC && (LegalOperations || (!LegalOperations && VT.isPow2VectorType()))) But the comment right after it is: // sext(setcc) -> sext_in_reg(vsetcc) for vectors. // Only do this before legalize for now. if (VT.isVector() && !LegalOperations) { So, these optimizations are never safe in the general case if we can't

I agree, that doesn't look right. It looks like this is what was intended: Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp =================================================================== --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp (revision 65000) +++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp (working copy) @@ -4903,9 +4903,9 @@ // resultant store does not need a higher alignment than

I'm running into lots of problems with this call back. Mostly the problem occurs because this callback is used before types are legalized. However, the code generator does not have a 1-1 correspondence between all LLVM types and the codegen types. This leads to problems when getSetCCResultType is passed in an invalid type, but has a valid LLVM type attached to it. An example is <3 x