RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2025-01-03 18:29:50 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Make the 'shrink global to bool' optimization more self contained, and thus

Browse Source 
easier to show that its safe.  No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45946 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-01-14 01:17:44 +00:00
parent 37ac608623
commit 58e44f49dd
1 changed files with 25 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -1257,9 +1257,28 @@ static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal,
return false;
}
/// ShrinkGlobalToBoolean - At this point, we have learned that the only two
/// values ever stored into GV are its initializer and OtherVal.
static void ShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
/// TryToShrinkGlobalToBoolean - At this point, we have learned that the only
/// two values ever stored into GV are its initializer and OtherVal. See if we
/// can shrink the global into a boolean and select between the two values
/// whenever it is used. This exposes the values to other scalar optimizations.
static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
const Type *GVElType = GV->getType()->getElementType();
// If GVElType is already i1, it is already shrunk. If the type of the GV is
// an FP value or vector, don't do this optimization because a select between
// them is very expensive and unlikely to lead to later simplification.
if (GVElType == Type::Int1Ty || GVElType->isFloatingPoint() ||
isa<VectorType>(GVElType))
return false;
// Walk the use list of the global seeing if all the uses are load or store.
// If there is anything else, bail out.
for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E; ++I)
if (!isa<LoadInst>(I) && !isa<StoreInst>(I))
return false;
DOUT << " *** SHRINKING TO BOOL: " << *GV;
// Create the new global, initializing it to false.
GlobalVariable *NewGV = new GlobalVariable(Type::Int1Ty, false,
GlobalValue::InternalLinkage, ConstantInt::getFalse(),
@ -1307,7 +1326,7 @@ static void ShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
}
}
new StoreInst(StoreVal, NewGV, SI);
} else if (!UI->use_empty()) {
} else {
// Change the load into a load of bool then a select.
LoadInst *LI = cast<LoadInst>(UI);
LoadInst *NLI = new LoadInst(NewGV, LI->getName()+".b", LI);
@ -1323,6 +1342,7 @@ static void ShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
}
GV->eraseFromParent();
return true;
}
@ -1464,12 +1484,7 @@ bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
// Otherwise, if the global was not a boolean, we can shrink it to be a
// boolean.
if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue))
if (GV->getType()->getElementType() != Type::Int1Ty &&
!GV->getType()->getElementType()->isFloatingPoint() &&
!isa<VectorType>(GV->getType()->getElementType()) &&
!GS.HasPHIUser && !GS.isNotSuitableForSRA) {
DOUT << " *** SHRINKING TO BOOL: " << *GV;
ShrinkGlobalToBoolean(GV, SOVConstant);
if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) {
++NumShrunkToBool;
return true;
}