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[MemDepAnalysis/VNCoercion] Move static method to its only use. [NFCI] 

Static method MemoryDependenceResults::getLoadLoadClobberFullWidthSize
does not have or use any info specific to MemoryDependenceResults.
Move it to its only user: VNCoercion.
This commit is contained in:
Alina Sbirlea 2020-01-17 15:02:32 -08:00
parent 128e1ebd93
commit 9f6c6ee6b9
3 changed files with 87 additions and 92 deletions
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12
llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
View File

@ -468,18 +468,6 @@ public:
/// with the same queried instruction.
MemDepResult getInvariantGroupPointerDependency(LoadInst *LI, BasicBlock *BB);
/// Looks at a memory location for a load (specified by MemLocBase, Offs, and
/// Size) and compares it against a load.
///
/// If the specified load could be safely widened to a larger integer load
/// that is 1) still efficient, 2) safe for the target, and 3) would provide
/// the specified memory location value, then this function returns the size
/// in bytes of the load width to use. If not, this returns zero.
static unsigned getLoadLoadClobberFullWidthSize(const Value *MemLocBase,
int64_t MemLocOffs,
unsigned MemLocSize,
const LoadInst *LI);
/// Release memory in caches.
void releaseMemory();

77
llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
View File

@ -238,83 +238,6 @@ MemDepResult MemoryDependenceResults::getCallDependencyFrom(
return MemDepResult::getNonFuncLocal();
}
unsigned MemoryDependenceResults::getLoadLoadClobberFullWidthSize(
const Value *MemLocBase, int64_t MemLocOffs, unsigned MemLocSize,
const LoadInst *LI) {
// We can only extend simple integer loads.
if (!isa<IntegerType>(LI->getType()) || !LI->isSimple())
return 0;
// Load widening is hostile to ThreadSanitizer: it may cause false positives
// or make the reports more cryptic (access sizes are wrong).
if (LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread))
return 0;
const DataLayout &DL = LI->getModule()->getDataLayout();
// Get the base of this load.
int64_t LIOffs = 0;
const Value *LIBase =
GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, DL);
// If the two pointers are not based on the same pointer, we can't tell that
// they are related.
if (LIBase != MemLocBase)
return 0;
// Okay, the two values are based on the same pointer, but returned as
// no-alias. This happens when we have things like two byte loads at "P+1"
// and "P+3". Check to see if increasing the size of the "LI" load up to its
// alignment (or the largest native integer type) will allow us to load all
// the bits required by MemLoc.
// If MemLoc is before LI, then no widening of LI will help us out.
if (MemLocOffs < LIOffs)
return 0;
// Get the alignment of the load in bytes. We assume that it is safe to load
// any legal integer up to this size without a problem. For example, if we're
// looking at an i8 load on x86-32 that is known 1024 byte aligned, we can
// widen it up to an i32 load. If it is known 2-byte aligned, we can widen it
// to i16.
unsigned LoadAlign = LI->getAlignment();
int64_t MemLocEnd = MemLocOffs + MemLocSize;
// If no amount of rounding up will let MemLoc fit into LI, then bail out.
if (LIOffs + LoadAlign < MemLocEnd)
return 0;
// This is the size of the load to try. Start with the next larger power of
// two.
unsigned NewLoadByteSize = LI->getType()->getPrimitiveSizeInBits() / 8U;
NewLoadByteSize = NextPowerOf2(NewLoadByteSize);
while (true) {
// If this load size is bigger than our known alignment or would not fit
// into a native integer register, then we fail.
if (NewLoadByteSize > LoadAlign ||
!DL.fitsInLegalInteger(NewLoadByteSize * 8))
return 0;
if (LIOffs + NewLoadByteSize > MemLocEnd &&
(LI->getParent()->getParent()->hasFnAttribute(
Attribute::SanitizeAddress) ||
LI->getParent()->getParent()->hasFnAttribute(
Attribute::SanitizeHWAddress)))
// We will be reading past the location accessed by the original program.
// While this is safe in a regular build, Address Safety analysis tools
// may start reporting false warnings. So, don't do widening.
return 0;
// If a load of this width would include all of MemLoc, then we succeed.
if (LIOffs + NewLoadByteSize >= MemLocEnd)
return NewLoadByteSize;
NewLoadByteSize <<= 1;
}
}
static bool isVolatile(Instruction *Inst) {
if (auto *LI = dyn_cast<LoadInst>(Inst))
return LI->isVolatile();

90
llvm/lib/Transforms/Utils/VNCoercion.cpp
View File

@ -1,7 +1,6 @@
#include "llvm/Transforms/Utils/VNCoercion.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/IntrinsicInst.h"
@ -240,6 +239,91 @@ int analyzeLoadFromClobberingStore(Type *LoadTy, Value *LoadPtr,
DL);
}
/// Looks at a memory location for a load (specified by MemLocBase, Offs, and
/// Size) and compares it against a load.
///
/// If the specified load could be safely widened to a larger integer load
/// that is 1) still efficient, 2) safe for the target, and 3) would provide
/// the specified memory location value, then this function returns the size
/// in bytes of the load width to use. If not, this returns zero.
static unsigned getLoadLoadClobberFullWidthSize(const Value *MemLocBase,
int64_t MemLocOffs,
unsigned MemLocSize,
const LoadInst *LI) {
// We can only extend simple integer loads.
if (!isa<IntegerType>(LI->getType()) || !LI->isSimple())
return 0;
// Load widening is hostile to ThreadSanitizer: it may cause false positives
// or make the reports more cryptic (access sizes are wrong).
if (LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread))
return 0;
const DataLayout &DL = LI->getModule()->getDataLayout();
// Get the base of this load.
int64_t LIOffs = 0;
const Value *LIBase =
GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, DL);
// If the two pointers are not based on the same pointer, we can't tell that
// they are related.
if (LIBase != MemLocBase)
return 0;
// Okay, the two values are based on the same pointer, but returned as
// no-alias. This happens when we have things like two byte loads at "P+1"
// and "P+3". Check to see if increasing the size of the "LI" load up to its
// alignment (or the largest native integer type) will allow us to load all
// the bits required by MemLoc.
// If MemLoc is before LI, then no widening of LI will help us out.
if (MemLocOffs < LIOffs)
return 0;
// Get the alignment of the load in bytes. We assume that it is safe to load
// any legal integer up to this size without a problem. For example, if we're
// looking at an i8 load on x86-32 that is known 1024 byte aligned, we can
// widen it up to an i32 load. If it is known 2-byte aligned, we can widen it
// to i16.
unsigned LoadAlign = LI->getAlignment();
int64_t MemLocEnd = MemLocOffs + MemLocSize;
// If no amount of rounding up will let MemLoc fit into LI, then bail out.
if (LIOffs + LoadAlign < MemLocEnd)
return 0;
// This is the size of the load to try. Start with the next larger power of
// two.
unsigned NewLoadByteSize = LI->getType()->getPrimitiveSizeInBits() / 8U;
NewLoadByteSize = NextPowerOf2(NewLoadByteSize);
while (true) {
// If this load size is bigger than our known alignment or would not fit
// into a native integer register, then we fail.
if (NewLoadByteSize > LoadAlign ||
!DL.fitsInLegalInteger(NewLoadByteSize * 8))
return 0;
if (LIOffs + NewLoadByteSize > MemLocEnd &&
(LI->getParent()->getParent()->hasFnAttribute(
Attribute::SanitizeAddress) ||
LI->getParent()->getParent()->hasFnAttribute(
Attribute::SanitizeHWAddress)))
// We will be reading past the location accessed by the original program.
// While this is safe in a regular build, Address Safety analysis tools
// may start reporting false warnings. So, don't do widening.
return 0;
// If a load of this width would include all of MemLoc, then we succeed.
if (LIOffs + NewLoadByteSize >= MemLocEnd)
return NewLoadByteSize;
NewLoadByteSize <<= 1;
}
}
/// This function is called when we have a
/// memdep query of a load that ends up being clobbered by another load. See if
/// the other load can feed into the second load.
@ -267,8 +351,8 @@ int analyzeLoadFromClobberingLoad(Type *LoadTy, Value *LoadPtr, LoadInst *DepLI,
GetPointerBaseWithConstantOffset(LoadPtr, LoadOffs, DL);
unsigned LoadSize = DL.getTypeStoreSize(LoadTy);
unsigned Size = MemoryDependenceResults::getLoadLoadClobberFullWidthSize(
LoadBase, LoadOffs, LoadSize, DepLI);
unsigned Size =
getLoadLoadClobberFullWidthSize(LoadBase, LoadOffs, LoadSize, DepLI);
if (Size == 0)
return -1;