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move isBytewiseValue out to ValueTracking.h/cpp

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llvm-svn: 122565
This commit is contained in:
Chris Lattner 2010-12-26 20:15:01 +00:00
parent 73f562af94
commit c56d20aa48
3 changed files with 77 additions and 69 deletions
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8
include/llvm/Analysis/ValueTracking.h
View File

@ -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.

69
lib/Analysis/ValueTracking.cpp
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@ -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<ConstantFP>(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<ConstantInt>(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<ConstantArray>(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

69
lib/Transforms/Scalar/MemCpyOptimizer.cpp
View File

@ -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<ConstantFP>(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<ConstantInt>(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<ConstantArray>(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.