diff options
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 10 | ||||
| -rw-r--r-- | test/Analysis/BasicAA/nocapture.ll | 21 |
2 files changed, 26 insertions, 5 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index 131b9d65e6..4bb93ee88a 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -58,12 +58,12 @@ static bool isNonEscapingLocalObject(const Value *V) { // then it has not escaped before entering the function. Check if it escapes // inside the function. if (const Argument *A = dyn_cast<Argument>(V)) - if (A->hasByValAttr() || A->hasNoAliasAttr()) { - // Don't bother analyzing arguments already known not to escape. - if (A->hasNoCaptureAttr()) - return true; + if (A->hasByValAttr() || A->hasNoAliasAttr()) + // Note even if the argument is marked nocapture we still need to check + // for copies made inside the function. The nocapture attribute only + // specifies that there are no copies made that outlive the function. return !PointerMayBeCaptured(V, false, /*StoreCaptures=*/true); - } + return false; } diff --git a/test/Analysis/BasicAA/nocapture.ll b/test/Analysis/BasicAA/nocapture.ll index a8658ec801..ffc0a09a07 100644 --- a/test/Analysis/BasicAA/nocapture.ll +++ b/test/Analysis/BasicAA/nocapture.ll @@ -13,3 +13,24 @@ define i32 @test2() { ret i32 %c } +declare void @test3(i32** %p, i32* %q) nounwind + +define i32 @test4(i32* noalias nocapture %p) nounwind { +; CHECK: call void @test3 +; CHECK: store i32 0, i32* %p +; CHECK: store i32 1, i32* %x +; CHECK: %y = load i32* %p +; CHECK: ret i32 %y +entry: + %q = alloca i32* + ; Here test3 might store %p to %q. This doesn't violate %p's nocapture + ; attribute since the copy doesn't outlive the function. + call void @test3(i32** %q, i32* %p) nounwind + store i32 0, i32* %p + %x = load i32** %q + ; This store might write to %p and so we can't eliminate the subsequent + ; load + store i32 1, i32* %x + %y = load i32* %p + ret i32 %y +} |