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Relax CFG assertions in UninitializedValuesV2 when 

handling pseudo-path sensitivity, and instead
use those assertion conditions as dynamic checks.
These assertions would be violated when analyzing
a CFG where some branches where optimized away
during CFG construction because their branch
conditions could be trivially determined.

llvm-svn: 123943
This commit is contained in:
Ted Kremenek 2011-01-20 21:25:31 +00:00
parent f07426b40d
commit cdca8fa97d
2 changed files with 41 additions and 14 deletions
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27
clang/lib/Analysis/UninitializedValuesV2.cpp
View File

@ -156,7 +156,7 @@ static BinaryOperator *getLogicalOperatorInChain(const CFGBlock *block) {
llvm::BitVector &CFGBlockValues::getBitVector(const CFGBlock *block,
const CFGBlock *dstBlock) {
unsigned idx = block->getBlockID();
if (dstBlock && block->succ_size() == 2) {
if (dstBlock && block->succ_size() == 2 && block->pred_size() == 2) {
assert(block->getTerminator());
if (getLogicalOperatorInChain(block)) {
if (*block->succ_begin() == dstBlock)
@ -460,20 +460,19 @@ static bool runOnBlock(const CFGBlock *block, const CFG &cfg,
UninitVariablesHandler *handler = 0) {
if (const BinaryOperator *b = getLogicalOperatorInChain(block)) {
assert(block->pred_size() == 2);
assert(block->succ_size() == 2);
assert(block->getTerminatorCondition() == b);
BVPair valsAB = vals.getPredBitVectors(block);
vals.mergeIntoScratch(*valsAB.first, true);
vals.mergeIntoScratch(*valsAB.second, false);
valsAB.second = &vals.getScratch();
if (b->getOpcode() == BO_LOr) {
// Ensure the invariant that 'first' corresponds to the true
// branch and 'second' to the false.
std::swap(valsAB.first, valsAB.second);
if (block->pred_size() == 2 && block->succ_size() == 2) {
assert(block->getTerminatorCondition() == b);
BVPair valsAB = vals.getPredBitVectors(block);
vals.mergeIntoScratch(*valsAB.first, true);
vals.mergeIntoScratch(*valsAB.second, false);
valsAB.second = &vals.getScratch();
if (b->getOpcode() == BO_LOr) {
// Ensure the invariant that 'first' corresponds to the true
// branch and 'second' to the false.
std::swap(valsAB.first, valsAB.second);
}
return vals.updateBitVectors(block, valsAB);
}
return vals.updateBitVectors(block, valsAB);
}
// Default behavior: merge in values of predecessor blocks.

28
clang/test/SemaCXX/uninit-variables.cpp
View File

@ -13,3 +13,31 @@ int test2_aux() {
return x; // no-warning
}
// Handle cases where the CFG may constant fold some branches, thus
// mitigating the need for some path-sensitivity in the analysis.
unsigned test3_aux();
unsigned test3() {
unsigned x = 0;
const bool flag = true;
if (flag && (x = test3_aux()) == 0) {
return x;
}
return x;
}
unsigned test3_b() {
unsigned x ;
const bool flag = true;
if (flag && (x = test3_aux()) == 0) {
x = 1;
}
return x; // no-warning
}
unsigned test3_c() {
unsigned x ;
const bool flag = false;
if (flag && (x = test3_aux()) == 0) {
x = 1;
}
return x; // expected-warning{{use of uninitialized variable 'x'}}
}