diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 84 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/load-cmp.ll | 12 |
2 files changed, 70 insertions, 26 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 088e440ed2..6cda71b8a3 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -6043,15 +6043,16 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, // Variables for our state machines. - // OnlyTrueElement - Used to emit a comparison of "i == 47", where 47 is the - // only index the condition is true for. The values are -1 -> undef, - // -2 -> overdef, >= 0 -> that index is true. - int OnlyTrueElement = -1; + // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form + // "i == 47 | i == 87", where 47 is the first index the condition is true for, + // and 87 is the second (and last) index. FirstTrueElement is -1 when + // undefined, otherwise set to the first true element. SecondTrueElement is + // -1 when undefined, -2 when overdefined and >= 0 when that index is true. + int FirstTrueElement = -1, SecondTrueElement = -1; - // OnlyFalseElement - Used to emit a comparison of "i != 47", where 47 is the - // only index the condition is false for. The values are -1 -> undef, - // -2 -> overdef, >= 0 -> that index is false. - int OnlyFalseElement = -1; + // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the + // form "i != 47 & i != 87". Same state transitions as for true elements. + int FirstFalseElement = -1, SecondFalseElement = -1; // MagicBitvector - This is a magic bitvector where we set a bit if the // comparison is true for element 'i'. If there are 64 elements or less in @@ -6079,11 +6080,21 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, // State machine for single index comparison. if (IsTrueForElt) { - // If undefined -> defined. Otherwise -> overdefined. - OnlyTrueElement = OnlyTrueElement == -1 ? i : -2; + // Update the TrueElement state machine. + if (FirstTrueElement == -1) + FirstTrueElement = i; + else if (SecondTrueElement == -1) + SecondTrueElement = i; + else + SecondTrueElement = -2; } else { - // If undefined -> defined. Otherwise -> overdefined. - OnlyFalseElement = OnlyFalseElement == -1 ? i : -2; + // Update the FalseElement state machine. + if (FirstFalseElement == -1) + FirstFalseElement = i; + else if (SecondFalseElement == -1) + SecondFalseElement = i; + else + SecondFalseElement = -2; } // If this element is in range, update our magic bitvector. @@ -6091,31 +6102,52 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, MagicBitvector |= 1ULL << i; // If all of our states become overdefined, bail out early. - if (i >= 64 && OnlyTrueElement == -2 && OnlyFalseElement == -2) + if (i >= 64 && SecondTrueElement == -2 && SecondFalseElement == -2) return 0; } // Now that we've scanned the entire array, emit our new comparison(s). We // order the state machines in complexity of the generated code. - if (OnlyTrueElement != -2) { + Value *Idx = GEP->getOperand(2); + + // If the comparison is only true for one or two elements, emit direct + // comparisons. + if (SecondTrueElement != -2) { // None true -> false. - if (OnlyTrueElement == -1) + if (FirstTrueElement == -1) return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context)); + Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); + // True for one element -> 'i == 47'. - return new ICmpInst(ICmpInst::ICMP_EQ, GEP->getOperand(2), - ConstantInt::get(GEP->getOperand(2)->getType(), - OnlyTrueElement)); + if (SecondTrueElement == -1) + return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); + + // True for two elements -> 'i == 47 | i == 72'. + Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx); + Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); + Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx); + return BinaryOperator::CreateOr(C1, C2); } - if (OnlyFalseElement != -2) { + // If the comparison is only false for one or two elements, emit direct + // comparisons. + if (SecondFalseElement != -2) { // None false -> true. - if (OnlyFalseElement == -1) + if (FirstFalseElement == -1) return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context)); - return new ICmpInst(ICmpInst::ICMP_NE, GEP->getOperand(2), - ConstantInt::get(GEP->getOperand(2)->getType(), - OnlyFalseElement)); + Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); + + // False for one element -> 'i != 47'. + if (SecondFalseElement == -1) + return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); + + // False for two elements -> 'i != 47 & i != 72'. + Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx); + Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); + Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx); + return BinaryOperator::CreateAnd(C1, C2); } // If a 32-bit or 64-bit magic bitvector captures the entire comparison state @@ -6128,14 +6160,14 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, Ty = Type::getInt32Ty(Init->getContext()); else Ty = Type::getInt64Ty(Init->getContext()); - Value *V = Builder->CreateIntCast(GEP->getOperand(2), Ty, false); + Value *V = Builder->CreateIntCast(Idx, Ty, false); V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V); return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); } - // TODO: Range check, two compares. - + // TODO: Range check + // TODO: GEP 0, i, 4 return 0; } diff --git a/test/Transforms/InstCombine/load-cmp.ll b/test/Transforms/InstCombine/load-cmp.ll index e44105791a..fabafed93f 100644 --- a/test/Transforms/InstCombine/load-cmp.ll +++ b/test/Transforms/InstCombine/load-cmp.ll @@ -45,3 +45,15 @@ define i1 @test4(i32 %X) { ; CHECK-NEXT: %R = icmp ne i32 {{.*}}, 0 ; CHECK-NEXT: ret i1 %R } + +define i1 @test5(i32 %X) { + %P = getelementptr [10 x i16]* @G16, i32 0, i32 %X + %Q = load i16* %P + %R = icmp eq i16 %Q, 69 + ret i1 %R +; CHECK: @test5 +; CHECK-NEXT: icmp eq i32 %X, 2 +; CHECK-NEXT: icmp eq i32 %X, 7 +; CHECK-NEXT: %R = or i1 +; CHECK-NEXT: ret i1 %R +} |