llvm-6502/test/Transforms/GlobalOpt/tls.ll
Hans Wennborg 1839858983 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
2012-11-15 11:40:00 +00:00

54 lines
1.5 KiB
LLVM

; 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
}