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author | Nick Lewycky <nicholas@mxc.ca> | 2012-01-23 00:05:17 +0000 |
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committer | Nick Lewycky <nicholas@mxc.ca> | 2012-01-23 00:05:17 +0000 |
commit | 37abc488a0527bb682af5aa6c4f376b5b99d67e4 (patch) | |
tree | 13d1df3a5e17ba9f525ed60688ff0a9c4d9692d4 /lib/VMCore | |
parent | 1906d32e55224b7481cd9e5726bd5e14b55f5cc1 (diff) | |
download | external_llvm-37abc488a0527bb682af5aa6c4f376b5b99d67e4.zip external_llvm-37abc488a0527bb682af5aa6c4f376b5b99d67e4.tar.gz external_llvm-37abc488a0527bb682af5aa6c4f376b5b99d67e4.tar.bz2 |
Make Value::isDereferenceablePointer() handle unreachable code blocks. (This
returns false in the event the computation feeding into the pointer is
unreachable, which maybe ought to be true -- but this is at least consistent
with undef->isDereferenceablePointer().) Fixes PR11825!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148671 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/VMCore')
-rw-r--r-- | lib/VMCore/Value.cpp | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp index a5f1918..207c06d 100644 --- a/lib/VMCore/Value.cpp +++ b/lib/VMCore/Value.cpp @@ -349,7 +349,8 @@ Value *Value::stripPointerCasts() { /// isDereferenceablePointer - Test if this value is always a pointer to /// allocated and suitably aligned memory for a simple load or store. -bool Value::isDereferenceablePointer() const { +static bool isDereferenceablePointer(const Value *V, + SmallPtrSet<const Value *, 32> &Visited) { // Note that it is not safe to speculate into a malloc'd region because // malloc may return null. // It's also not always safe to follow a bitcast, for example: @@ -358,20 +359,22 @@ bool Value::isDereferenceablePointer() const { // be handled using TargetData to check sizes and alignments though. // These are obviously ok. - if (isa<AllocaInst>(this)) return true; + if (isa<AllocaInst>(V)) return true; // Global variables which can't collapse to null are ok. - if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this)) + if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) return !GV->hasExternalWeakLinkage(); // byval arguments are ok. - if (const Argument *A = dyn_cast<Argument>(this)) + if (const Argument *A = dyn_cast<Argument>(V)) return A->hasByValAttr(); - + // For GEPs, determine if the indexing lands within the allocated object. - if (const GEPOperator *GEP = dyn_cast<GEPOperator>(this)) { + if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { // Conservatively require that the base pointer be fully dereferenceable. - if (!GEP->getOperand(0)->isDereferenceablePointer()) + if (!Visited.insert(GEP->getOperand(0))) + return false; + if (!isDereferenceablePointer(GEP->getOperand(0), Visited)) return false; // Check the indices. gep_type_iterator GTI = gep_type_begin(GEP); @@ -405,6 +408,13 @@ bool Value::isDereferenceablePointer() const { return false; } +/// isDereferenceablePointer - Test if this value is always a pointer to +/// allocated and suitably aligned memory for a simple load or store. +bool Value::isDereferenceablePointer() const { + SmallPtrSet<const Value *, 32> Visited; + return ::isDereferenceablePointer(this, Visited); +} + /// DoPHITranslation - If this value is a PHI node with CurBB as its parent, /// return the value in the PHI node corresponding to PredBB. If not, return /// ourself. This is useful if you want to know the value something has in a |