[SanitizerCoverage] Add stack depth tracing instrumentation.

Summary:
Augment SanitizerCoverage to insert maximum stack depth tracing for
use by libFuzzer.  The new instrumentation is enabled by the flag
-fsanitize-coverage=stack-depth and is compatible with the existing
trace-pc-guard coverage.  The user must also declare the following
global variable in their code:
  thread_local uintptr_t __sancov_lowest_stack

https://bugs.llvm.org/show_bug.cgi?id=33857

Reviewers: vitalybuka, kcc

Reviewed By: vitalybuka

Subscribers: kubamracek, hiraditya, cfe-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D36839

llvm-svn: 311186

1 files changed, 50 insertions, 0 deletions

diff --git a/llvm/test/Instrumentation/SanitizerCoverage/stack-depth.ll b/llvm/test/Instrumentation/SanitizerCoverage/stack-depth.ll
new file mode 100644
index 00000000000..015f5676bc8
--- /dev/null
+++ b/llvm/test/Instrumentation/SanitizerCoverage/stack-depth.ll
@@ -0,0 +1,50 @@
+; This check verifies that stack depth instrumentation works correctly.
+; RUN: opt < %s -sancov -sanitizer-coverage-level=1 \
+; RUN:     -sanitizer-coverage-stack-depth -S | FileCheck %s --enable-var-scope
+; RUN: opt < %s -sancov -sanitizer-coverage-level=3 \
+; RUN:     -sanitizer-coverage-stack-depth -sanitizer-coverage-trace-pc-guard \
+; RUN:     -S | FileCheck %s --enable-var-scope
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK: @__sancov_lowest_stack = thread_local global i64 -1
+@__sancov_lowest_stack = thread_local global i64 0, align 8
+
+define i32 @foo() {
+entry:
+; CHECK-LABEL: define i32 @foo
+; CHECK: [[framePtr:%[^ \t]+]] = call i8* @llvm.frameaddress(i32 0)
+; CHECK: [[frameInt:%[^ \t]+]] = ptrtoint i8* [[framePtr]] to [[$intType:i[0-9]+]]
+; CHECK: [[lowestPtr:%[^ \t]+]] = call [[$intType]]* @_ZTW21__sancov_lowest_stack
+; CHECK: [[lowestInt:%[^ \t]+]] = load [[$intType]], [[$intType]]* [[lowestPtr]]
+; CHECK: [[cmp:%[^ \t]+]] = icmp ult [[$intType]] [[frameInt]], [[lowestInt]]
+; CHECK: br i1 [[cmp]], label %[[ifLabel:[^ \t]+]], label
+; CHECK: <label>:[[ifLabel]]:
+; CHECK: store [[$intType]] [[frameInt]], [[$intType]]* [[lowestPtr]]
+; CHECK: ret i32 7
+
+  ret i32 7
+}
+
+define i32 @bar() {
+entry:
+; CHECK-LABEL: define i32 @bar
+; CHECK: [[framePtr:%[^ \t]+]] = call i8* @llvm.frameaddress(i32 0)
+; CHECK: [[frameInt:%[^ \t]+]] = ptrtoint i8* [[framePtr]] to [[$intType]]
+; CHECK: [[lowestPtr:%[^ \t]+]] = call [[$intType]]* @_ZTW21__sancov_lowest_stack
+; CHECK: [[lowestInt:%[^ \t]+]] = load [[$intType]], [[$intType]]* [[lowestPtr]]
+; CHECK: [[cmp:%[^ \t]+]] = icmp ult [[$intType]] [[frameInt]], [[lowestInt]]
+; CHECK: br i1 [[cmp]], label %[[ifLabel:[^ \t]+]], label
+; CHECK: <label>:[[ifLabel]]:
+; CHECK: store [[$intType]] [[frameInt]], [[$intType]]* [[lowestPtr]]
+; CHECK: %call = call i32 @foo()
+; CHECK: ret i32 %call
+
+  %call = call i32 @foo()
+  ret i32 %call
+}
+
+define weak_odr hidden i64* @_ZTW21__sancov_lowest_stack() {
+  ret i64* @__sancov_lowest_stack
+}