diff --git a/lib/Analysis/CFLAliasAnalysis.cpp b/lib/Analysis/CFLAliasAnalysis.cpp index 676b6161d0a..82fbfe06aee 100644 --- a/lib/Analysis/CFLAliasAnalysis.cpp +++ b/lib/Analysis/CFLAliasAnalysis.cpp @@ -43,6 +43,7 @@ #include "llvm/Pass.h" #include "llvm/Support/Allocator.h" #include "llvm/Support/Compiler.h" +#include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include #include @@ -51,6 +52,8 @@ using namespace llvm; +#define DEBUG_TYPE "cfl-aa" + // Try to go from a Value* to a Function*. Never returns nullptr. static Optional parentFunctionOfValue(Value *); @@ -229,6 +232,7 @@ public: if (isa(LocA.Ptr) && isa(LocB.Ptr)) { return AliasAnalysis::alias(LocA, LocB); } + AliasResult QueryResult = query(LocA, LocB); if (QueryResult == MayAlias) return AliasAnalysis::alias(LocA, LocB); @@ -973,8 +977,10 @@ CFLAliasAnalysis::query(const AliasAnalysis::Location &LocA, auto MaybeFnA = parentFunctionOfValue(ValA); auto MaybeFnB = parentFunctionOfValue(ValB); if (!MaybeFnA.hasValue() && !MaybeFnB.hasValue()) { - llvm_unreachable("Don't know how to extract the parent function " - "from values A or B"); + // The only times this is known to happen are when globals + InlineAsm + // are involved + DEBUG(dbgs() << "CFLAA: could not extract parent function information.\n"); + return AliasAnalysis::MayAlias; } if (MaybeFnA.hasValue()) { @@ -1002,14 +1008,15 @@ CFLAliasAnalysis::query(const AliasAnalysis::Location &LocA, auto SetB = *MaybeB; auto AttrsA = Sets.getLink(SetA.Index).Attrs; auto AttrsB = Sets.getLink(SetB.Index).Attrs; + // Stratified set attributes are used as markets to signify whether a member - // of a StratifiedSet (or a member of a set above the current set) has + // of a StratifiedSet (or a member of a set above the current set) has // interacted with either arguments or globals. "Interacted with" meaning - // its value may be different depending on the value of an argument or + // its value may be different depending on the value of an argument or // global. The thought behind this is that, because arguments and globals // may alias each other, if AttrsA and AttrsB have touched args/globals, - // we must conservatively say that they alias. However, if at least one of - // the sets has no values that could legally be altered by changing the value + // we must conservatively say that they alias. However, if at least one of + // the sets has no values that could legally be altered by changing the value // of an argument or global, then we don't have to be as conservative. if (AttrsA.any() && AttrsB.any()) return AliasAnalysis::MayAlias; diff --git a/test/Analysis/CFLAliasAnalysis/asm-global-bugfix.ll b/test/Analysis/CFLAliasAnalysis/asm-global-bugfix.ll new file mode 100644 index 00000000000..d8ee94ba65c --- /dev/null +++ b/test/Analysis/CFLAliasAnalysis/asm-global-bugfix.ll @@ -0,0 +1,16 @@ +; Test case for a bug where we would crash when we were requested to report +; whether two values that didn't belong to a function (i.e. two globals, etc) +; aliased. + +; RUN: opt < %s -cfl-aa -aa-eval -print-may-aliases -disable-output 2>&1 | FileCheck %s + +@G = private unnamed_addr constant [1 x i8] c"\00", align 1 + +; CHECK: Function: test_no_crash +; CHECK: 1 no alias responses +define void @test_no_crash() #0 { +entry: + call i8* asm "nop", "=r,r"( + i8* getelementptr inbounds ([1 x i8]* @G, i64 0, i64 0)) + ret void +}