diff options
Diffstat (limited to 'lib/Analysis/BasicAliasAnalysis.cpp')
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index 81b9f842249e..537813b6b752 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -781,6 +781,7 @@ ModRefInfo BasicAAResult::getModRefInfo(ImmutableCallSite CS, // Optimistically assume that call doesn't touch Object and check this // assumption in the following loop. ModRefInfo Result = ModRefInfo::NoModRef; + bool IsMustAlias = true; unsigned OperandNo = 0; for (auto CI = CS.data_operands_begin(), CE = CS.data_operands_end(); @@ -802,7 +803,8 @@ ModRefInfo BasicAAResult::getModRefInfo(ImmutableCallSite CS, // is impossible to alias the pointer we're checking. AliasResult AR = getBestAAResults().alias(MemoryLocation(*CI), MemoryLocation(Object)); - + if (AR != MustAlias) + IsMustAlias = false; // Operand doesnt alias 'Object', continue looking for other aliases if (AR == NoAlias) continue; @@ -818,13 +820,20 @@ ModRefInfo BasicAAResult::getModRefInfo(ImmutableCallSite CS, continue; } // This operand aliases 'Object' and call reads and writes into it. + // Setting ModRef will not yield an early return below, MustAlias is not + // used further. Result = ModRefInfo::ModRef; break; } + // No operand aliases, reset Must bit. Add below if at least one aliases + // and all aliases found are MustAlias. + if (isNoModRef(Result)) + IsMustAlias = false; + // Early return if we improved mod ref information if (!isModAndRefSet(Result)) - return Result; + return IsMustAlias ? setMust(Result) : clearMust(Result); } // If the CallSite is to malloc or calloc, we can assume that it doesn't |