This revision was automatically updated to reflect the committed changes.
Closed by commit rL342734: NFC: deduplicate isRepeatedBytePattern from clang to
LLVM's isBytewiseValue (authored by jfb, committed by ).
Herald added a subscriber: llvm-commits.
Repository:
rL LLVM
https://reviews.llvm.org/D51752
Files:
cfe/trunk/lib/CodeGen/CGDecl.cpp
Index: cfe/trunk/lib/CodeGen/CGDecl.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp
@@ -30,6 +30,7 @@
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "clang/Frontend/CodeGenOptions.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Intrinsics.h"
@@ -948,111 +949,17 @@
canEmitInitWithFewStoresAfterBZero(Init, StoreBudget);
}
-/// A byte pattern.
-///
-/// Can be "any" pattern if the value was padding or known to be undef.
-/// Can be "none" pattern if a sequence doesn't exist.
-class BytePattern {
- uint8_t Val;
- enum class ValueType : uint8_t { Specific, Any, None } Type;
- BytePattern(ValueType Type) : Type(Type) {}
-
-public:
- BytePattern(uint8_t Value) : Val(Value), Type(ValueType::Specific) {}
- static BytePattern Any() { return BytePattern(ValueType::Any); }
- static BytePattern None() { return BytePattern(ValueType::None); }
- bool isAny() const { return Type == ValueType::Any; }
- bool isNone() const { return Type == ValueType::None; }
- bool isValued() const { return Type == ValueType::Specific; }
- uint8_t getValue() const {
- assert(isValued());
- return Val;
- }
- BytePattern merge(const BytePattern Other) const {
- if (isNone() || Other.isNone())
- return None();
- if (isAny())
- return Other;
- if (Other.isAny())
- return *this;
- if (getValue() == Other.getValue())
- return *this;
- return None();
- }
-};
-
-/// Figures out whether the constant can be initialized with memset.
-static BytePattern constantIsRepeatedBytePattern(llvm::Constant *C) {
- if (isa<llvm::ConstantAggregateZero>(C) || isa<llvm::ConstantPointerNull>(C))
- return BytePattern(0x00);
- if (isa<llvm::UndefValue>(C))
- return BytePattern::Any();
-
- if (isa<llvm::ConstantInt>(C)) {
- auto *Int = cast<llvm::ConstantInt>(C);
- if (Int->getBitWidth() % 8 != 0)
- return BytePattern::None();
- const llvm::APInt &Value = Int->getValue();
- if (Value.isSplat(8))
- return BytePattern(Value.getLoBits(8).getLimitedValue());
- return BytePattern::None();
- }
-
- if (isa<llvm::ConstantFP>(C)) {
- auto *FP = cast<llvm::ConstantFP>(C);
- llvm::APInt Bits = FP->getValueAPF().bitcastToAPInt();
- if (Bits.getBitWidth() % 8 != 0)
- return BytePattern::None();
- if (!Bits.isSplat(8))
- return BytePattern::None();
- return BytePattern(Bits.getLimitedValue() & 0xFF);
- }
-
- if (isa<llvm::ConstantVector>(C)) {
- llvm::Constant *Splat = cast<llvm::ConstantVector>(C)->getSplatValue();
- if (Splat)
- return constantIsRepeatedBytePattern(Splat);
- return BytePattern::None();
- }
-
- if (isa<llvm::ConstantArray>(C) || isa<llvm::ConstantStruct>(C)) {
- BytePattern Pattern(BytePattern::Any());
- for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) {
- llvm::Constant *Elt = cast<llvm::Constant>(C->getOperand(I));
- Pattern = Pattern.merge(constantIsRepeatedBytePattern(Elt));
- if (Pattern.isNone())
- return Pattern;
- }
- return Pattern;
- }
-
- if (llvm::ConstantDataSequential *CDS =
- dyn_cast<llvm::ConstantDataSequential>(C)) {
- BytePattern Pattern(BytePattern::Any());
- for (unsigned I = 0, E = CDS->getNumElements(); I != E; ++I) {
- llvm::Constant *Elt = CDS->getElementAsConstant(I);
- Pattern = Pattern.merge(constantIsRepeatedBytePattern(Elt));
- if (Pattern.isNone())
- return Pattern;
- }
- return Pattern;
- }
-
- // BlockAddress, ConstantExpr, and everything else is scary.
- return BytePattern::None();
-}
-
/// Decide whether we should use memset to initialize a local variable instead
/// of using a memcpy from a constant global. Assumes we've already decided to
/// not user bzero.
/// FIXME We could be more clever, as we are for bzero above, and generate
/// memset followed by stores. It's unclear that's worth the effort.
-static BytePattern shouldUseMemSetToInitialize(llvm::Constant *Init,
- uint64_t GlobalSize) {
+static llvm::Value *shouldUseMemSetToInitialize(llvm::Constant *Init,
+ uint64_t GlobalSize) {
uint64_t SizeLimit = 32;
if (GlobalSize <= SizeLimit)
- return BytePattern::None();
- return constantIsRepeatedBytePattern(Init);
+ return nullptr;
+ return llvm::isBytewiseValue(Init);
}
static void emitStoresForConstant(CodeGenModule &CGM, const VarDecl &D,
@@ -1081,9 +988,14 @@
return;
}
- BytePattern Pattern = shouldUseMemSetToInitialize(constant, ConstantSize);
- if (!Pattern.isNone()) {
- uint8_t Value = Pattern.isAny() ? 0x00 : Pattern.getValue();
+ llvm::Value *Pattern = shouldUseMemSetToInitialize(constant, ConstantSize);
+ if (Pattern) {
+ uint64_t Value = 0x00;
+ if (!isa<llvm::UndefValue>(Pattern)) {
+ const llvm::APInt &AP = cast<llvm::ConstantInt>(Pattern)->getValue();
+ assert(AP.getBitWidth() <= 8);
+ Value = AP.getLimitedValue();
+ }
Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, Value), SizeVal,
isVolatile);
return;
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