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-rw-r--r--llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h5
-rw-r--r--llvm/lib/Analysis/MemoryDependenceAnalysis.cpp42
-rw-r--r--llvm/lib/Transforms/Scalar/GVN.cpp80
-rw-r--r--llvm/test/Transforms/GVN/memcpy.ll1
4 files changed, 125 insertions, 3 deletions
diff --git a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
index 356f8214c3d..c6ef41ff240 100644
--- a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -100,6 +100,11 @@ class MemoryDependenceAnalysis : public FunctionPass {
/// updating the dependence of instructions that previously depended on it.
void removeInstruction(Instruction* rem);
+ /// dropInstruction - Remove an instruction from the analysis, making
+ /// absolutely conservative assumptions when updating the cache. This is
+ /// useful, for example when an instruction is changed rather than removed.
+ void dropInstruction(Instruction* drop);
+
private:
Instruction* getCallSiteDependency(CallSite C, Instruction* start,
BasicBlock* block);
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 36c18f0c0b5..22c454fae15 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -457,6 +457,46 @@ Instruction* MemoryDependenceAnalysis::getDependency(Instruction* query,
return NonLocal;
}
+/// dropInstruction - Remove an instruction from the analysis, making
+/// absolutely conservative assumptions when updating the cache. This is
+/// useful, for example when an instruction is changed rather than removed.
+void MemoryDependenceAnalysis::dropInstruction(Instruction* drop) {
+ depMapType::iterator depGraphEntry = depGraphLocal.find(drop);
+ if (depGraphEntry != depGraphLocal.end())
+ reverseDep[depGraphEntry->second.first].erase(drop);
+
+ // Drop dependency information for things that depended on this instr
+ SmallPtrSet<Instruction*, 4>& set = reverseDep[drop];
+ for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
+ I != E; ++I)
+ depGraphLocal.erase(*I);
+
+ depGraphLocal.erase(drop);
+ reverseDep.erase(drop);
+
+ for (DenseMap<BasicBlock*, Value*>::iterator DI =
+ depGraphNonLocal[drop].begin(), DE = depGraphNonLocal[drop].end();
+ DI != DE; ++DI)
+ if (DI->second != None)
+ reverseDepNonLocal[DI->second].erase(drop);
+
+ if (reverseDepNonLocal.count(drop)) {
+ SmallPtrSet<Instruction*, 4>& set = reverseDepNonLocal[drop];
+ for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
+ I != E; ++I)
+ for (DenseMap<BasicBlock*, Value*>::iterator DI =
+ depGraphNonLocal[*I].begin(), DE = depGraphNonLocal[*I].end();
+ DI != DE; ++DI)
+ if (DI->second == drop)
+ DI->second = Dirty;
+ }
+
+ reverseDepNonLocal.erase(drop);
+ nonLocalDepMapType::iterator I = depGraphNonLocal.find(drop);
+ if (I != depGraphNonLocal.end())
+ depGraphNonLocal.erase(I);
+}
+
/// removeInstruction - Remove an instruction from the dependence analysis,
/// updating the dependence of instructions that previously depended on it.
/// This method attempts to keep the cache coherent using the reverse map.
@@ -473,7 +513,7 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction* rem) {
depMapType::iterator depGraphEntry = depGraphLocal.find(rem);
if (depGraphEntry != depGraphLocal.end()) {
- reverseDep[depGraphLocal[rem].first].erase(rem);
+ reverseDep[depGraphEntry->second.first].erase(rem);
if (depGraphEntry->second.first != NonLocal &&
depGraphEntry->second.first != None &&
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 69f06909f6c..95bb0ddfbc4 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -19,6 +19,7 @@
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Instructions.h"
#include "llvm/Value.h"
#include "llvm/ADT/BitVector.h"
@@ -736,6 +737,7 @@ namespace {
SmallVector<Instruction*, 4>& toErase);
bool processNonLocalLoad(LoadInst* L,
SmallVector<Instruction*, 4>& toErase);
+ bool processMemCpy(MemCpyInst* M, SmallVector<Instruction*, 4>& toErase);
Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
DenseMap<BasicBlock*, Value*> &Phis,
bool top_level = false);
@@ -1044,6 +1046,79 @@ bool GVN::processLoad(LoadInst* L,
return deletedLoad;
}
+/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which
+/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be
+/// a memcpy from X to Z (or potentially a memmove, depending on circumstances).
+/// This allows later passes to remove the first memcpy altogether.
+bool GVN::processMemCpy(MemCpyInst* M,
+ SmallVector<Instruction*, 4>& toErase) {
+ MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
+
+ // First, we have to check that the dependency is another memcpy
+ Instruction* dep = MD.getDependency(M);
+ if (dep == MemoryDependenceAnalysis::None ||
+ dep == MemoryDependenceAnalysis::NonLocal ||
+ !isa<MemCpyInst>(dep))
+ return false;
+
+ // We can only transforms memcpy's where the dest of one is the source of the
+ // other
+ MemCpyInst* MDep = cast<MemCpyInst>(dep);
+ if (M->getSource() != MDep->getDest())
+ return false;
+
+ // Second, the length of the memcpy's must be the same, or the preceeding one
+ // must be larger than the following one.
+ ConstantInt* C1 = dyn_cast<ConstantInt>(MDep->getLength());
+ ConstantInt* C2 = dyn_cast<ConstantInt>(M->getLength());
+ if (!C1 || !C2)
+ return false;
+
+ uint64_t CpySize = C1->getValue().getZExtValue();
+ uint64_t DepSize = C2->getValue().getZExtValue();
+
+ if (DepSize < CpySize)
+ return false;
+
+ // Finally, we have to make sure that the dest of the second does not
+ // alias the source of the first
+ AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
+ if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) !=
+ AliasAnalysis::NoAlias)
+ return false;
+ else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) !=
+ AliasAnalysis::NoAlias)
+ return false;
+ else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize)
+ != AliasAnalysis::NoAlias)
+ return false;
+
+ // If all checks passed, then we can transform these memcpy's
+ bool is32bit = M->getIntrinsicID() == Intrinsic::memcpy_i32;
+ Function* MemMoveFun = Intrinsic::getDeclaration(
+ M->getParent()->getParent()->getParent(),
+ is32bit ? Intrinsic::memcpy_i32 :
+ Intrinsic::memcpy_i64);
+
+ std::vector<Value*> args;
+ args.push_back(M->getRawDest());
+ args.push_back(MDep->getRawSource());
+ args.push_back(M->getLength());
+ args.push_back(M->getAlignment());
+
+ CallInst* C = new CallInst(MemMoveFun, args.begin(), args.end(), "", M);
+
+ if (MD.getDependency(C) == MDep) {
+ MD.dropInstruction(M);
+ toErase.push_back(M);
+ return true;
+ } else {
+ MD.removeInstruction(C);
+ toErase.push_back(C);
+ return false;
+ }
+}
+
/// processInstruction - When calculating availability, handle an instruction
/// by inserting it into the appropriate sets
bool GVN::processInstruction(Instruction* I,
@@ -1052,6 +1127,8 @@ bool GVN::processInstruction(Instruction* I,
SmallVector<Instruction*, 4>& toErase) {
if (LoadInst* L = dyn_cast<LoadInst>(I)) {
return processLoad(L, lastSeenLoad, toErase);
+ } else if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) {
+ return processMemCpy(M, toErase);
}
unsigned num = VN.lookup_or_add(I);
@@ -1161,8 +1238,9 @@ bool GVN::iterateOnFunction(Function &F) {
++BI;
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I)
+ E = toErase.end(); I != E; ++I) {
(*I)->eraseFromParent();
+ }
toErase.clear();
}
diff --git a/llvm/test/Transforms/GVN/memcpy.ll b/llvm/test/Transforms/GVN/memcpy.ll
index 1884a9ecd81..31e55c8b160 100644
--- a/llvm/test/Transforms/GVN/memcpy.ll
+++ b/llvm/test/Transforms/GVN/memcpy.ll
@@ -1,5 +1,4 @@
; RUN: llvm-as < %s | opt -gvn -dse | llvm-dis | grep memcpy | count 2
-; XFAIL: *
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i686-apple-darwin9"
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