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Make these loops follow GetGEPOperands() behavior. 

Let: %q = GEP %p, X, ...
If %p is a GEP, we can chase baseptr further, only if X==0.

llvm-svn: 44999
This commit is contained in:
Wojciech Matyjewicz 2007-12-13 16:22:58 +00:00
parent a5be19d3df
commit 86d51b896e
1 changed files with 13 additions and 11 deletions
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24
llvm/lib/Analysis/BasicAliasAnalysis.cpp
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@ -391,17 +391,19 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
if (isGEP(V1) && isGEP(V2)) {
// Drill down into the first non-gep value, to test for must-aliasing of
// the base pointers.
const Value *BasePtr1 = V1, *BasePtr2 = V2;
do {
BasePtr1 = cast<User>(BasePtr1)->getOperand(0);
} while (isGEP(BasePtr1) &&
cast<User>(BasePtr1)->getOperand(1) ==
Constant::getNullValue(cast<User>(BasePtr1)->getOperand(1)->getType()));
do {
BasePtr2 = cast<User>(BasePtr2)->getOperand(0);
} while (isGEP(BasePtr2) &&
cast<User>(BasePtr2)->getOperand(1) ==
Constant::getNullValue(cast<User>(BasePtr2)->getOperand(1)->getType()));
const User *G = cast<User>(V1);
while (isGEP(G->getOperand(0)) &&
G->getOperand(1) ==
Constant::getNullValue(G->getOperand(1)->getType()))
G = cast<User>(G->getOperand(0));
const Value *BasePtr1 = G->getOperand(0);
G = cast<User>(V2);
while (isGEP(G->getOperand(0)) &&
G->getOperand(1) ==
Constant::getNullValue(G->getOperand(1)->getType()))
G = cast<User>(G->getOperand(0));
const Value *BasePtr2 = G->getOperand(0);
// Do the base pointers alias?
AliasResult BaseAlias = alias(BasePtr1, ~0U, BasePtr2, ~0U);