Obey the isVolatile bit on memory intrinsics when analyzing uses of a global

variable. Noticed by inspection.

Simulate memset in EvaluateFunction where the target of the memset and the
value we're setting are both the null value. Fixes PR10047!

llvm-svn: 132288

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/test/Transforms/GlobalOpt/memset-null.ll b/llvm/test/Transforms/GlobalOpt/memset-null.ll
new file mode 100644
index 00000000000..7a24a2a22be
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/memset-null.ll
@@ -0,0 +1,19 @@
+; RUN: opt -globalopt %s -S -o - | FileCheck %s
+; PR10047
+
+
+%0 = type { i32, void ()* }
+%struct.A = type { [100 x i32] }
+
+; CHECK: @a
+@a = global %struct.A zeroinitializer, align 4
+@llvm.global_ctors = appending global [1 x %0] [%0 { i32 65535, void ()* @_GLOBAL__I_a }]
+
+declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
+
+; CHECK-NOT: GLOBAL__I_a
+define internal void @_GLOBAL__I_a() nounwind {
+entry:
+  tail call void @llvm.memset.p0i8.i64(i8* bitcast (%struct.A* @a to i8*), i8 0, i64 400, i32 4, i1 false) nounwind
+  ret void
+}