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Make AllUsesOfLoadedValueWillTrapIfNull strong enough to see through PHI 

nodes.  This is the first step of the fix for PR1639.

llvm-svn: 41927
This commit is contained in:
Chris Lattner 2007-09-13 16:30:19 +00:00
parent d3d8aca074
commit 2d2892ee6e
1 changed files with 15 additions and 6 deletions
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21
llvm/lib/Transforms/IPO/GlobalOpt.cpp
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@ -26,6 +26,7 @@
#include "llvm/Target/TargetData.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
@ -493,8 +494,10 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV) {
}
/// AllUsesOfValueWillTrapIfNull - Return true if all users of the specified
/// value will trap if the value is dynamically null.
static bool AllUsesOfValueWillTrapIfNull(Value *V) {
/// value will trap if the value is dynamically null. PHIs keeps track of any
/// phi nodes we've seen to avoid reprocessing them.
static bool AllUsesOfValueWillTrapIfNull(Value *V,
SmallPtrSet<PHINode*, 8> &PHIs) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
if (isa<LoadInst>(*UI)) {
// Will trap.
@ -513,10 +516,15 @@ static bool AllUsesOfValueWillTrapIfNull(Value *V) {
//cerr << "NONTRAPPING USE: " << **UI;
return false; // Not calling the ptr
}
} else if (CastInst *CI = dyn_cast<CastInst>(*UI)) {
if (!AllUsesOfValueWillTrapIfNull(CI)) return false;
} else if (BitCastInst *CI = dyn_cast<BitCastInst>(*UI)) {
if (!AllUsesOfValueWillTrapIfNull(CI, PHIs)) return false;
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI)) {
if (!AllUsesOfValueWillTrapIfNull(GEPI)) return false;
if (!AllUsesOfValueWillTrapIfNull(GEPI, PHIs)) return false;
} else if (PHINode *PN = dyn_cast<PHINode>(*UI)) {
// If we've already seen this phi node, ignore it, it has already been
// checked.
if (PHIs.insert(PN))
return AllUsesOfValueWillTrapIfNull(PN, PHIs);
} else if (isa<ICmpInst>(*UI) &&
isa<ConstantPointerNull>(UI->getOperand(1))) {
// Ignore setcc X, null
@ -533,7 +541,8 @@ static bool AllUsesOfValueWillTrapIfNull(Value *V) {
static bool AllUsesOfLoadedValueWillTrapIfNull(GlobalVariable *GV) {
for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end(); UI!=E; ++UI)
if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
if (!AllUsesOfValueWillTrapIfNull(LI))
SmallPtrSet<PHINode*, 8> PHIs;
if (!AllUsesOfValueWillTrapIfNull(LI, PHIs))
return false;
} else if (isa<StoreInst>(*UI)) {
// Ignore stores to the global.