From: Chris Lattner Date: Sun, 26 Dec 2010 20:15:01 +0000 (+0000) Subject: move isBytewiseValue out to ValueTracking.h/cpp X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=bb89710dddf967199dfc56e8bf5d28b0003f2ee6;p=oota-llvm.git move isBytewiseValue out to ValueTracking.h/cpp git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122565 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h index dcc150d18d9..370282d0c08 100644 --- a/include/llvm/Analysis/ValueTracking.h +++ b/include/llvm/Analysis/ValueTracking.h @@ -77,7 +77,13 @@ namespace llvm { /// bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0); - + /// isBytewiseValue - If the specified value can be set by repeating the same + /// byte in memory, return the i8 value that it is represented with. This is + /// true for all i8 values obviously, but is also true for i32 0, i32 -1, + /// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated + /// byte store (e.g. i16 0x1234), return null. + Value *isBytewiseValue(Value *V); + /// FindInsertedValue - Given an aggregrate and an sequence of indices, see if /// the scalar value indexed is already around as a register, for example if /// it were inserted directly into the aggregrate. diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index f8145cd0e3d..6f58afe5279 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -989,6 +989,75 @@ bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { return false; } +/// isBytewiseValue - If the specified value can be set by repeating the same +/// byte in memory, return the i8 value that it is represented with. This is +/// true for all i8 values obviously, but is also true for i32 0, i32 -1, +/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated +/// byte store (e.g. i16 0x1234), return null. +Value *llvm::isBytewiseValue(Value *V) { + // All byte-wide stores are splatable, even of arbitrary variables. + if (V->getType()->isIntegerTy(8)) return V; + + // Constant float and double values can be handled as integer values if the + // corresponding integer value is "byteable". An important case is 0.0. + if (ConstantFP *CFP = dyn_cast(V)) { + if (CFP->getType()->isFloatTy()) + V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext())); + if (CFP->getType()->isDoubleTy()) + V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext())); + // Don't handle long double formats, which have strange constraints. + } + + // We can handle constant integers that are power of two in size and a + // multiple of 8 bits. + if (ConstantInt *CI = dyn_cast(V)) { + unsigned Width = CI->getBitWidth(); + if (isPowerOf2_32(Width) && Width > 8) { + // We can handle this value if the recursive binary decomposition is the + // same at all levels. + APInt Val = CI->getValue(); + APInt Val2; + while (Val.getBitWidth() != 8) { + unsigned NextWidth = Val.getBitWidth()/2; + Val2 = Val.lshr(NextWidth); + Val2 = Val2.trunc(Val.getBitWidth()/2); + Val = Val.trunc(Val.getBitWidth()/2); + + // If the top/bottom halves aren't the same, reject it. + if (Val != Val2) + return 0; + } + return ConstantInt::get(V->getContext(), Val); + } + } + + // A ConstantArray is splatable if all its members are equal and also + // splatable. + if (ConstantArray *CA = dyn_cast(V)) { + if (CA->getNumOperands() == 0) + return 0; + + Value *Val = isBytewiseValue(CA->getOperand(0)); + if (!Val) + return 0; + + for (unsigned I = 1, E = CA->getNumOperands(); I != E; ++I) + if (CA->getOperand(I-1) != CA->getOperand(I)) + return 0; + + return Val; + } + + // Conceptually, we could handle things like: + // %a = zext i8 %X to i16 + // %b = shl i16 %a, 8 + // %c = or i16 %a, %b + // but until there is an example that actually needs this, it doesn't seem + // worth worrying about. + return 0; +} + + // This is the recursive version of BuildSubAggregate. It takes a few different // arguments. Idxs is the index within the nested struct From that we are // looking at now (which is of type IndexedType). IdxSkip is the number of diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp index a927207f66a..00ee1457857 100644 --- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp +++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp @@ -22,6 +22,7 @@ #include "llvm/Analysis/Dominators.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/Analysis/MemoryDependenceAnalysis.h" +#include "llvm/Analysis/ValueTracking.h" #include "llvm/Support/Debug.h" #include "llvm/Support/GetElementPtrTypeIterator.h" #include "llvm/Support/raw_ostream.h" @@ -34,74 +35,6 @@ STATISTIC(NumMemSetInfer, "Number of memsets inferred"); STATISTIC(NumMoveToCpy, "Number of memmoves converted to memcpy"); STATISTIC(NumCpyToSet, "Number of memcpys converted to memset"); -/// isBytewiseValue - If the specified value can be set by repeating the same -/// byte in memory, return the i8 value that it is represented with. This is -/// true for all i8 values obviously, but is also true for i32 0, i32 -1, -/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated -/// byte store (e.g. i16 0x1234), return null. -static Value *isBytewiseValue(Value *V) { - // All byte-wide stores are splatable, even of arbitrary variables. - if (V->getType()->isIntegerTy(8)) return V; - - // Constant float and double values can be handled as integer values if the - // corresponding integer value is "byteable". An important case is 0.0. - if (ConstantFP *CFP = dyn_cast(V)) { - if (CFP->getType()->isFloatTy()) - V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext())); - if (CFP->getType()->isDoubleTy()) - V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext())); - // Don't handle long double formats, which have strange constraints. - } - - // We can handle constant integers that are power of two in size and a - // multiple of 8 bits. - if (ConstantInt *CI = dyn_cast(V)) { - unsigned Width = CI->getBitWidth(); - if (isPowerOf2_32(Width) && Width > 8) { - // We can handle this value if the recursive binary decomposition is the - // same at all levels. - APInt Val = CI->getValue(); - APInt Val2; - while (Val.getBitWidth() != 8) { - unsigned NextWidth = Val.getBitWidth()/2; - Val2 = Val.lshr(NextWidth); - Val2 = Val2.trunc(Val.getBitWidth()/2); - Val = Val.trunc(Val.getBitWidth()/2); - - // If the top/bottom halves aren't the same, reject it. - if (Val != Val2) - return 0; - } - return ConstantInt::get(V->getContext(), Val); - } - } - - // A ConstantArray is splatable if all its members are equal and also - // splatable. - if (ConstantArray *CA = dyn_cast(V)) { - if (CA->getNumOperands() == 0) - return 0; - - Value *Val = isBytewiseValue(CA->getOperand(0)); - if (!Val) - return 0; - - for (unsigned I = 1, E = CA->getNumOperands(); I != E; ++I) - if (CA->getOperand(I-1) != CA->getOperand(I)) - return 0; - - return Val; - } - - // Conceptually, we could handle things like: - // %a = zext i8 %X to i16 - // %b = shl i16 %a, 8 - // %c = or i16 %a, %b - // but until there is an example that actually needs this, it doesn't seem - // worth worrying about. - return 0; -} - static int64_t GetOffsetFromIndex(const GetElementPtrInst *GEP, unsigned Idx, bool &VariableIdxFound, TargetData &TD) { // Skip over the first indices.