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llvm-mirror/test/Instrumentation/ThreadSanitizer/read_before_write.ll
Marco Elver 155722cf56 [TSan] Add option for emitting compound read-write instrumentation
This adds option -tsan-compound-read-before-write to emit different
instrumentation for the write if the read before that write is omitted
from instrumentation. The default TSan runtime currently does not
support the different instrumentation, and the option is disabled by
default.

Alternative runtimes, such as the Kernel Concurrency Sanitizer (KCSAN)
can make use of the feature. Indeed, the initial motivation is for use
in KCSAN as it was determined that due to the Linux kernel having a
large number of unaddressed data races, it makes sense to improve
performance and reporting by distinguishing compounded operations. E.g.
the compounded instrumentation is typically emitted for compound
operations such as ++, +=, |=, etc. By emitting different reports, such
data races can easily be noticed, and also automatically bucketed
differently by CI systems.

Reviewed By: dvyukov, glider

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83867
2020-07-17 10:24:20 +02:00

82 lines
2.7 KiB
LLVM

; RUN: opt < %s -tsan -S | FileCheck --check-prefixes=CHECK,CHECK-OPT %s
; RUN: opt < %s -tsan -tsan-instrument-read-before-write -S | FileCheck %s --check-prefixes=CHECK,CHECK-UNOPT
; RUN: opt < %s -tsan -tsan-compound-read-before-write -S | FileCheck %s --check-prefixes=CHECK,CHECK-COMPOUND
; RUN: opt < %s -tsan -tsan-distinguish-volatile -tsan-compound-read-before-write -S | FileCheck %s --check-prefixes=CHECK,CHECK-COMPOUND-VOLATILE
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
define void @IncrementMe(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
entry:
%0 = load i32, i32* %ptr, align 4
%inc = add nsw i32 %0, 1
store i32 %inc, i32* %ptr, align 4
ret void
}
; CHECK-LABEL: define void @IncrementMe
; CHECK-OPT-NOT: __tsan_read4
; CHECK-COMPOUND-NOT: __tsan_read4
; CHECK-UNOPT: __tsan_read4
; CHECK-OPT: __tsan_write4
; CHECK-UNOPT: __tsan_write4
; CHECK-COMPOUND: __tsan_read_write4
; CHECK: ret void
define void @IncrementMeWithCallInBetween(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
entry:
%0 = load i32, i32* %ptr, align 4
%inc = add nsw i32 %0, 1
call void @foo()
store i32 %inc, i32* %ptr, align 4
ret void
}
; CHECK-LABEL: define void @IncrementMeWithCallInBetween
; CHECK: __tsan_read4
; CHECK: __tsan_write4
; CHECK: ret void
declare void @foo()
define void @VolatileLoad(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
entry:
%0 = load volatile i32, i32* %ptr, align 4
%inc = add nsw i32 %0, 1
store i32 %inc, i32* %ptr, align 4
ret void
}
; CHECK-LABEL: define void @VolatileLoad
; CHECK-COMPOUND-NOT: __tsan_read4
; CHECK-COMPOUND-VOLATILE: __tsan_volatile_read4
; CHECK-COMPOUND: __tsan_read_write4
; CHECK-COMPOUND-VOLATILE: __tsan_write4
; CHECK: ret void
define void @VolatileStore(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
entry:
%0 = load i32, i32* %ptr, align 4
%inc = add nsw i32 %0, 1
store volatile i32 %inc, i32* %ptr, align 4
ret void
}
; CHECK-LABEL: define void @VolatileStore
; CHECK-COMPOUND-NOT: __tsan_read4
; CHECK-COMPOUND-VOLATILE: __tsan_read4
; CHECK-COMPOUND: __tsan_read_write4
; CHECK-COMPOUND-VOLATILE: __tsan_volatile_write4
; CHECK: ret void
define void @VolatileBoth(i32* nocapture %ptr) nounwind uwtable sanitize_thread {
entry:
%0 = load volatile i32, i32* %ptr, align 4
%inc = add nsw i32 %0, 1
store volatile i32 %inc, i32* %ptr, align 4
ret void
}
; CHECK-LABEL: define void @VolatileBoth
; CHECK-COMPOUND-NOT: __tsan_read4
; CHECK-COMPOUND-VOLATILE: __tsan_volatile_read4
; CHECK-COMPOUND: __tsan_read_write4
; CHECK-COMPOUND-VOLATILE: __tsan_volatile_write4
; CHECK: ret void