search for: hasnosignedwrap

...p:3099-3113), but only Add and GEP operators are checked. //-------------------------------------------------------------------------// if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) { if (OBO->hasNoUnsignedWrap()) Flags = setFlags(Flags, SCEV::FlagNUW); if (OBO->hasNoSignedWrap()) Flags = setFlags(Flags, SCEV::FlagNSW); } else if (const GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { // If the increment is an inbounds GEP, then we know the address // space cannot be wrapped around. We cannot make any guarantee // about signed or unsigned...

...i8 1, i8 -128" does not sign overflow (by the usual definition of sign-overflow), so this violates (2). InstCombine already has a check for this edge-case when folding multiplies into left shifts: ... if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap(); if (I.hasNoSignedWrap() && *** NewCst->isNotMinSignedValue() ***) Shl->setHasNoSignedWrap(); ... (though the check is a bit weird -- NewCst is Log2(IVal) so I think it cannot ever be INT_MIN, and I suspect that the check is supposed to be "IVal->isNotMinSignedValue()" or equivalent....

.../InstCombine/InstCombineAddSub.cpp&ct=xref_jump_to_def&cl=GROK&l=1470&gsn=V>); Res <https://cs.corp.google.com/#piper///depot/google3/third_party/llvm/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp&ct=xref_jump_to_def&cl=GROK&l=1471&gsn=Res>->setHasNoSignedWrap <https://cs.corp.google.com/#piper///depot/google3/third_party/llvm/llvm/lib/IR/Instructions.cpp&ct=xref_jump_to_def&cl=GROK&l=2013&gsn=setHasNoSignedWrap>(I <https://cs.corp.google.com/#piper///depot/google3/third_party/llvm/llvm/lib/Transforms/InstCombine/InstCombineAddSu...

...and GEP operators are checked. > > //-------------------------------------------------------------------------// > if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) { > if (OBO->hasNoUnsignedWrap()) > Flags = setFlags(Flags, SCEV::FlagNUW); > if (OBO->hasNoSignedWrap()) > Flags = setFlags(Flags, SCEV::FlagNSW); > } else if (const GEPOperator *GEP = > dyn_cast<GEPOperator>(BEValueV)) { > // If the increment is an inbounds GEP, then we know the address > // space cannot be wrapped around. We cannot make any guarantee > //...

...> > > > //-------------------------------------------------------------------------// > > if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) { > > if (OBO->hasNoUnsignedWrap()) > > Flags = setFlags(Flags, SCEV::FlagNUW); > > if (OBO->hasNoSignedWrap()) > > Flags = setFlags(Flags, SCEV::FlagNSW); > > } else if (const GEPOperator *GEP = > > dyn_cast<GEPOperator>(BEValueV)) { > > // If the increment is an inbounds GEP, then we know the address > > // space cannot be wrapped around. We cannot ma...

Thanks for your reply. We are propagating sign info to tablegen currently using BinaryWithFlagsSDNode.Flags.hasNoSignedWrap atm. I imagine (I have not looked) they are printed according to instruction in AsmPrinter.cpp (pure speculation). I'm still confused as to why 0x7FFF is ok to match 16 bit int but not 0x8000? Thanks. On Wed, Feb 15, 2017 at 1:44 PM, Manuel Jacob <me at manueljacob.de> wrote: > Hi...

...<me at manueljacob.de> >> wrote: >> >>> On 2017-02-15 19:54, Ryan Taylor wrote: >>> >>>> Thanks for your reply. >>>> >>>> We are propagating sign info to tablegen currently using >>>> BinaryWithFlagsSDNode.Flags.hasNoSignedWrap atm. >>>> >>> >>> Note that this flag doesn't indicate signedness of the operation. It >>> just means that the optimizer or code generator can assume that no >>> signed >>> overflow will happen during the operation. To get a better...

...let mayLoad = 1; } On Wed, Feb 15, 2017 at 2:24 PM, Manuel Jacob <me at manueljacob.de> wrote: > On 2017-02-15 19:54, Ryan Taylor wrote: > >> Thanks for your reply. >> >> We are propagating sign info to tablegen currently using >> BinaryWithFlagsSDNode.Flags.hasNoSignedWrap atm. >> > > Note that this flag doesn't indicate signedness of the operation. It just > means that the optimizer or code generator can assume that no signed > overflow will happen during the operation. To get a better understanding > of why this flag is not suitable for r...

I'm curious why 'unsigned short w = 0x8000' is displayed as -32768 in the IR? This propagates to the DAG and hence tablegen, where I am missing matching on some immediates because the immediate is not being looked at as unsigned? For example, we have no issue if instead of 0x8000 we use 0x7FFF, then everything is fine, the match is fine. I can understand that it's just being

I've been doing some digging in this area (scev, wrapping arithmetic), learning as much as I can, and have reached a point where I'm fairly confused about the semantics of nuw in scalar evolution expressions. Consider the following program: define void @foo(i32 %begin) { entry: br label %loop loop: %idx = phi i32 [ %begin, %entry ], [ %idx.dec, %loop ] %idx.dec = sub nuw i32

You are right: select in SDAG has to be poison-blocking as well, otherwise the current lowering from IR's select to SDAG's select would be wrong. Which makes the select->or transformation incorrect at SDAG level as well. I guess until recently people believed that poison in SDAG wasn't much of a problem (myself included). I was convinced otherwise with the test cases that