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author | Hans Wennborg <hans@hanshq.net> | 2012-11-15 11:40:00 +0000 |
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committer | Hans Wennborg <hans@hanshq.net> | 2012-11-15 11:40:00 +0000 |
commit | 1839858983dcbaf1808a6a37f5cd64d92981f27e (patch) | |
tree | 1dcce5725cc713d41175088b57f33a93a3f6e8b6 /test/Transforms/GlobalOpt | |
parent | ac39a035351a20928e087617e412aa6ce510181f (diff) | |
download | llvm-1839858983dcbaf1808a6a37f5cd64d92981f27e.tar.gz llvm-1839858983dcbaf1808a6a37f5cd64d92981f27e.tar.bz2 llvm-1839858983dcbaf1808a6a37f5cd64d92981f27e.tar.xz |
Make GlobalOpt be conservative with TLS variables (PR14309)
For global variables that get the same value stored into them
everywhere, GlobalOpt will replace them with a constant. The problem is
that a thread-local GlobalVariable looks like one value (the address of
the TLS var), but is different between threads.
This patch introduces Constant::isThreadDependent() which returns true
for thread-local variables and constants which depend on them (e.g. a GEP
into a thread-local array), and teaches GlobalOpt not to track such
values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168037 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/Transforms/GlobalOpt')
-rw-r--r-- | test/Transforms/GlobalOpt/tls.ll | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/test/Transforms/GlobalOpt/tls.ll b/test/Transforms/GlobalOpt/tls.ll new file mode 100644 index 0000000000..7a410e5ed2 --- /dev/null +++ b/test/Transforms/GlobalOpt/tls.ll @@ -0,0 +1,53 @@ +; RUN: opt < %s -globalopt -S | FileCheck %s + +declare void @wait() +declare void @signal() +declare void @start_thread(void ()*) + +@x = internal thread_local global [100 x i32] zeroinitializer, align 16 +@ip = internal global i32* null, align 8 + +; PR14309: GlobalOpt would think that the value of @ip is always the address of +; x[1]. However, that address is different for different threads so @ip cannot +; be replaced with a constant. + +define i32 @f() { +entry: + ; Set @ip to point to x[1] for thread 1. + store i32* getelementptr inbounds ([100 x i32]* @x, i64 0, i64 1), i32** @ip, align 8 + + ; Run g on a new thread. + tail call void @start_thread(void ()* @g) nounwind + tail call void @wait() nounwind + + ; Reset x[1] for thread 1. + store i32 0, i32* getelementptr inbounds ([100 x i32]* @x, i64 0, i64 1), align 4 + + ; Read the value of @ip, which now points at x[1] for thread 2. + %0 = load i32** @ip, align 8 + + %1 = load i32* %0, align 4 + ret i32 %1 + +; CHECK: @f +; Make sure that the load from @ip hasn't been removed. +; CHECK: load i32** @ip +; CHECK: ret +} + +define internal void @g() nounwind uwtable { +entry: + ; Set @ip to point to x[1] for thread 2. + store i32* getelementptr inbounds ([100 x i32]* @x, i64 0, i64 1), i32** @ip, align 8 + + ; Store 50 in x[1] for thread 2. + store i32 50, i32* getelementptr inbounds ([100 x i32]* @x, i64 0, i64 1), align 4 + + tail call void @signal() nounwind + ret void + +; CHECK: @g +; Make sure that the store to @ip hasn't been removed. +; CHECK: store {{.*}} @ip +; CHECK: ret +} |