Stack Coloring: We have code that checks that all of the uses of allocas

are within the lifetime zone. Sometime legitimate usages of allocas are
hoisted outside of the lifetime zone. For example, GEPS may calculate the
address of a member of an allocated struct. This commit makes sure that
we only check (abort regions or assert) for instructions that read and write
memory using stack frames directly. Notice that by allowing legitimate
usages outside the lifetime zone we also stop checking for instructions
which use derivatives of allocas. We will catch less bugs in user code
and in the compiler itself.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163791 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/test/CodeGen/X86/StackColoring.ll b/test/CodeGen/X86/StackColoring.ll
index a83a4ebbe2..f8ae74f292 100644
--- a/test/CodeGen/X86/StackColoring.ll
+++ b/test/CodeGen/X86/StackColoring.ll
@@ -376,6 +376,30 @@ block2:
 }
 
 
+; Check that we don't assert and crash even when there are usages
+; of allocas which do not read or write outside the declared lifetime regions.
+;YESCOLOR: shady_range
+;NOCOLOR:  shady_range
+
+%struct.Klass = type { i32, i32 }
+
+define i32 @shady_range(i32 %argc, i8** nocapture %argv) uwtable {
+  %a.i = alloca [4 x %struct.Klass], align 16
+  %b.i = alloca [4 x %struct.Klass], align 16
+  %a8 = bitcast [4 x %struct.Klass]* %a.i to i8*
+  %b8 = bitcast [4 x %struct.Klass]* %b.i to i8*
+  ; I am used outside the lifetime zone below:
+  %z2 = getelementptr inbounds [4 x %struct.Klass]* %a.i, i64 0, i64 0, i32 0
+  call void @llvm.lifetime.start(i64 -1, i8* %a8)
+  call void @llvm.lifetime.start(i64 -1, i8* %b8)
+  %z3 = load i32* %z2, align 16
+  %r = call i32 @foo(i32 %z3, i8* %a8)
+  %r2 = call i32 @foo(i32 %z3, i8* %b8)
+  call void @llvm.lifetime.end(i64 -1, i8* %a8)
+  call void @llvm.lifetime.end(i64 -1, i8* %b8)
+  ret i32 9
+}
+
 declare void @bar([100 x i32]* , [100 x i32]*) nounwind
 
 declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind