RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-11-26 12:50:30 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Make GVN able to remove unnecessary calls to read-only functions again.

Browse Source 
llvm-svn: 49842
This commit is contained in:
Owen Anderson 2008-04-17 05:36:50 +00:00
parent 98aab12b63
commit cd1b9c4b43
3 changed files with 32 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
lib/Analysis/MemoryDependenceAnalysis.cpp
View File

@ -134,8 +134,7 @@ Instruction* MemoryDependenceAnalysis::getCallSiteDependency(CallSite C,
} else if (isa<CallInst>(QI)) {
AliasAnalysis::ModRefBehavior result =
AA.getModRefBehavior(CallSite::get(QI));
if (result != AliasAnalysis::DoesNotAccessMemory &&
result != AliasAnalysis::OnlyReadsMemory) {
if (result != AliasAnalysis::DoesNotAccessMemory) {
if (!start && !block) {
cachedResult.first = QI;
cachedResult.second = true;

46
lib/Transforms/Scalar/GVN.cpp
View File

@ -135,6 +135,7 @@ namespace {
DenseMap<Value*, uint32_t> valueNumbering;
DenseMap<Expression, uint32_t> expressionNumbering;
AliasAnalysis* AA;
MemoryDependenceAnalysis* MD;
uint32_t nextValueNumber;
@ -159,6 +160,7 @@ namespace {
void erase(Value* v);
unsigned size();
void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
};
}
@ -432,6 +434,33 @@ uint32_t ValueTable::lookup_or_add(Value* V) {
return nextValueNumber++;
}
} else if (AA->onlyReadsMemory(C)) {
Expression e = create_expression(C);
Instruction* dep = MD->getDependency(C);
if (dep == MemoryDependenceAnalysis::NonLocal ||
!isa<CallInst>(dep)) {
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
}
CallInst* cdep = cast<CallInst>(dep);
Expression d_exp = create_expression(cdep);
if (e != d_exp) {
expressionNumbering.insert(std::make_pair(e, nextValueNumber));
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
} else {
uint32_t v = expressionNumbering[d_exp];
valueNumbering.insert(std::make_pair(V, v));
return v;
}
} else {
valueNumbering.insert(std::make_pair(V, nextValueNumber));
return nextValueNumber++;
@ -993,22 +1022,6 @@ bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
} else if (currAvail.test(num)) {
Value* repl = find_leader(currAvail, num);
if (CallInst* CI = dyn_cast<CallInst>(I)) {
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
if (!AA.doesNotAccessMemory(CI)) {
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
if (cast<Instruction>(repl)->getParent() != CI->getParent() ||
MD.getDependency(CI) != MD.getDependency(cast<CallInst>(repl))) {
// There must be an intervening may-alias store, so nothing from
// this point on will be able to be replaced with the preceding call
currAvail.erase(repl);
currAvail.insert(I);
return false;
}
}
}
// Remove it!
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
MD.removeInstruction(I);
@ -1030,6 +1043,7 @@ bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
//
bool GVN::runOnFunction(Function& F) {
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
VN.setMemDep(&getAnalysis<MemoryDependenceAnalysis>());
bool changed = false;
bool shouldContinue = true;

2
test/Analysis/BasicAA/const-dce.ll → test/Analysis/BasicAA/pure-const-dce.ll
View File

@ -1,5 +1,5 @@
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestConst | count 2
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestPure | count 4
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestPure | count 3
; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep TestNone | count 4
@g = global i32 0 ; <i32*> [#uses=1]