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...asAnalysis::AliasResult > BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size, > const Value *V2, unsigned V2Size) { > + // Null pointers do not alias with anything > + if (const Constant *C = dyn_cast<Constant>(V1)) > + if (C->isNullValue()) > + return NoAlias; > + > + if (const Constant *C = dyn_cast<Constant>(V2)) > + if (C->isNullValue()) > + return NoAlias; > + As Chris mentioned, for consistency with what the rest of LLVM is doing, this should check whether the pointers are in the defa...

...ss R, L greater R). > [/new comment] > > > > > > +enum ConstantType { > > I'm not sure that this buys you much. All the "isa" tests can be > broken > > down into a switch on getValueID() with the one exception of > isNullValue(). > Done. > > > > + assert( > > + C1->getType()->__canLosslesslyBitCastTo(C2->__getType()) && > > + "Pass is healthless. checkForLosslessBitcast should be > twin of " > > + "canLossle...

This is the first patch I've sent to this project. Please be gentle :) LLVM fails to remove the dead load in the following code when running $./llvm-as -o - test.ll | ./opt -O3 -o - | ./llvm-dis -o - %t = type { i32 } declare void @foo(i8*) define void @f(%t* noalias nocapture %stuff ) { %p = getelementptr inbounds %t* %stuff, i32 0, i32 0 %before = load i32* %p call void

..."\000" string. Here is the code: Constant *ConstantArray::get(const ArrayType *Ty, const std::vector<Constant*> &V) { // If this is an all-zero array, return a ConstantAggregateZero object if (!V.empty()) { Constant *C = V[0]; if (!C->isNullValue()) return ArrayConstants->getOrCreate(Ty, V); for (unsigned i = 1, e = V.size(); i != e; ++i) if (V[i] != C) return ArrayConstants->getOrCreate(Ty, V); } return ConstantAggregateZero::get(Ty); } This seems wrong to me, and it's causing a problem in Objective-...

Yep check out PR1324. Doing something like this would be a great improvement. -Chris On Jan 21, 2012, at 9:42 AM, Duncan Sands <baldrick at free.fr> wrote: > Hi Anton, in a solution without CAZ, isNullValue can just return true when it > sees the special "this ConstantArray is all zero" flag. So all the places that > now look for CAZ can just use isNullValue instead and there need be no > performance loss. That said, CAZ is more "in your force" so less likely to be >...

...have been working on that produces bytecode that passes the verifier. However, when I try to read that bytecode back in, I get the assertion failure below. llvm::BytecodeReader::ParseConstantPoolValue(unsigned int): Assertion `(!isa<Constant>(Result) || !cast<Constant>(Result)->isNullValue()) || !hasImplicitNull(TypeID) && "Cannot read null values from bytecode!"' failed. So, I ran gdb on opt. I was able to get the following information from opt: (gdb) print Result $7 = (class llvm::Constant *) 0x96ad9d0 (gdb) call Result->dump() [41 x sbyte *] zeroini...

...nym is useful, and we at least need to have some recommendation for the “well known” ones). > > Example: > > if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) > if (CE->getOpcode() == Instruction::GetElementPtr && > CE->getOperand(0)->isNullValue()) { > > In the above example, is the recommendation to use “ce” instead of “CE” now? Or should it be “cE”? > With lowerCamelCase one might think that “cE” is the correct one (although I personally think that one looks quite ugly). In most examples, you’d use something other than an in...

Hi Anton, in a solution without CAZ, isNullValue can just return true when it sees the special "this ConstantArray is all zero" flag. So all the places that now look for CAZ can just use isNullValue instead and there need be no performance loss. That said, CAZ is more "in your force" so less likely to be forgotten about. A...

...3, "Chris Lattner" <clattner at apple.com>: > Yep check out PR1324.  Doing something like this would be a great improvement. > > -Chris > > On Jan 21, 2012, at 9:42 AM, Duncan Sands <baldrick at free.fr> wrote: > >>  Hi Anton, in a solution without CAZ, isNullValue can just return true when it >>  sees the special "this ConstantArray is all zero" flag.  So all the places that >>  now look for CAZ can just use isNullValue instead and there need be no >>  performance loss.  That said, CAZ is more "in your force" so less li...

The recently added code: static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) { if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, INFINITY); if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, -INFINITY); if (V2->isNullValue()) return 0; BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue(); return ConstantClass::get(*Ty, R); } does not compile with VC++. The symbol INFINITY is undefined, nor is there an equivalent I can find.

...y added code: >> static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) { >> if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, INFINITY); >> if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, >> -INFINITY); >> if (V2->isNullValue()) return 0; >> BuiltinType R = (BuiltinType)V1->getValue() / >> (BuiltinType)V2->getValue(); >> return ConstantClass::get(*Ty, R); >> } >> >> does not compile with VC++. The symbol INFINITY is undefined, nor is >> there an equivalent I can fi...

...duces > bytecode that passes the verifier. However, when I try to read that > bytecode back in, I get the assertion failure below. > > llvm::BytecodeReader::ParseConstantPoolValue(unsigned int): > Assertion `(!isa<Constant>(Result) || > !cast<Constant>(Result)->isNullValue()) || !hasImplicitNull(TypeID) && > "Cannot read null values from bytecode!"' failed. > > So, I ran gdb on opt. I was able to get the following information from opt: > > (gdb) print Result > $7 = (class llvm::Constant *) 0x96ad9d0 > (gdb) call Result-...

...ecode that passes the verifier. However, when I try to read that >>bytecode back in, I get the assertion failure below. >> >>llvm::BytecodeReader::ParseConstantPoolValue(unsigned int): >>Assertion `(!isa<Constant>(Result) || >>!cast<Constant>(Result)->isNullValue()) || !hasImplicitNull(TypeID) && >>"Cannot read null values from bytecode!"' failed. >> >>So, I ran gdb on opt. I was able to get the following information from opt: >> >>(gdb) print Result >>$7 = (class llvm::Constant *) 0x96ad9d0 >&...

...total ordering requires two values that indicates non-equivalence (L less R, L greater R). [/new comment] > > +enum ConstantType { > I'm not sure that this buys you much. All the "isa" tests can be broken > down into a switch on getValueID() with the one exception of isNullValue(). Done. > + assert( > + C1->getType()->canLosslesslyBitCastTo(C2->getType()) && > + "Pass is healthless. checkForLosslessBitcast should be twin of " > + "canLosslesslyBitCastTo method, except the case when the last one " &g...

...ult >> BasicAliasAnalysis::aliasCheck(const Value *V1, unsigned V1Size, >> const Value *V2, unsigned V2Size) { >> + // Null pointers do not alias with anything >> + if (const Constant *C = dyn_cast<Constant>(V1)) >> + if (C->isNullValue()) >> + return NoAlias; >> + >> + if (const Constant *C = dyn_cast<Constant>(V2)) >> + if (C->isNullValue()) >> + return NoAlias; >> + > > As Chris mentioned, for consistency with what the rest of LLVM is doing, > this should che...

...en wrote: > The recently added code: > static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) { > if (V2->isExactlyValue(0.0)) return ConstantClass::get(*Ty, INFINITY); > if (V2->isExactlyValue(-0.0)) return ConstantClass::get(*Ty, -INFINITY); > if (V2->isNullValue()) return 0; > BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue(); > return ConstantClass::get(*Ty, R); > } > > does not compile with VC++. The symbol INFINITY is undefined, nor is there > an equivalent I can find. Can std::numeric_limits be us...

On Mon, 2 May 2005, Jeff Cohen wrote: > Yes, that will work. I'll make the change. While you're at it, please remove this line, which is dead: if (V2->isNullValue()) return 0; Thanks, -Chris > Chris Lattner wrote: > >> On Mon, 2 May 2005, Jeff Cohen wrote: >> >>> The recently added code: >>> static Constant *Div(const ConstantClass *V1, const ConstantClass *V2) { >>> if (V2->isExactlyValue(0.0)) return C...

...emporary) solution is a hack, however: ================================================================== --- SparcAsmPrinter.cpp (revision 720) +++ SparcAsmPrinter.cpp (working copy) @@ -263,7 +263,7 @@ // FALL THROUGH case GlobalValue::InternalLinkage: if (C->isNullValue()) - SwitchToDataSection(".bss", I); + SwitchToDataSection("\t.section\t\".bss\"", I); else SwitchToDataSection(".data", I); break; My question is: What is the "right" way to do this? I l...

Sorry, forgot to reply-all ---------- Forwarded message ---------- From: Anton Korobeynikov <anton at korobeynikov.info> Date: Sat, Jan 21, 2012 at 20:59 Subject: Re: [LLVMdev] How to force the creation of arrays with zeroes? To: Stepan Dyatkovskiy <STPWORLD at narod.ru> > Though, there is also cases when we really need to transform it to 10,000 zeroes (just look at CBackend.cpp,

...m, you can do so by adding it to the instcombine pass. We'd need IR enhancements to do this sort of thing for real in the mid-level optimizer, some thoughts are here: > http://nondot.org/sabre/LLVMNotes/FloatingPointChanges.txt > Thanks, now it works. I inserted if (Op1F->isNullValue()) return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0 into llvm::InstCombiner::visitFMul Why not at first create a compile time option for this so that the code is already available for special purposes? -Jochen