Give the rdrand instructions a SideEffect flag and a chain so MachineCSE and MachineLICM don't touch it.

I already had the necessary things in place for IR-level passes but missed the machine passes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160137 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 38 insertions, 0 deletions

diff --git a/test/CodeGen/X86/rdrand.ll b/test/CodeGen/X86/rdrand.ll
index 78af936..27d1fe6 100644
--- a/test/CodeGen/X86/rdrand.ll
+++ b/test/CodeGen/X86/rdrand.ll
@@ -45,3 +45,41 @@ define i32 @_rdrand64_step(i64* %random_val) {
 ; CHECK: cmovael	%e[[T1]], %eax
 ; CHECK: ret
 }
+
+; Check that MachineCSE doesn't eliminate duplicate rdrand instructions.
+define i32 @CSE() nounwind {
+ %rand1 = tail call { i32, i32 } @llvm.x86.rdrand.32() nounwind
+ %v1 = extractvalue { i32, i32 } %rand1, 0
+ %rand2 = tail call { i32, i32 } @llvm.x86.rdrand.32() nounwind
+ %v2 = extractvalue { i32, i32 } %rand2, 0
+ %add = add i32 %v2, %v1
+ ret i32 %add
+; CHECK: CSE:
+; CHECK: rdrandl
+; CHECK: rdrandl
+}
+
+; Check that MachineLICM doesn't hoist rdrand instructions.
+define void @loop(i32* %p, i32 %n) nounwind {
+entry:
+  %tobool1 = icmp eq i32 %n, 0
+  br i1 %tobool1, label %while.end, label %while.body
+
+while.body:                                       ; preds = %entry, %while.body
+  %p.addr.03 = phi i32* [ %incdec.ptr, %while.body ], [ %p, %entry ]
+  %n.addr.02 = phi i32 [ %dec, %while.body ], [ %n, %entry ]
+  %dec = add nsw i32 %n.addr.02, -1
+  %incdec.ptr = getelementptr inbounds i32* %p.addr.03, i64 1
+  %rand = tail call { i32, i32 } @llvm.x86.rdrand.32() nounwind
+  %v1 = extractvalue { i32, i32 } %rand, 0
+  store i32 %v1, i32* %p.addr.03, align 4
+  %tobool = icmp eq i32 %dec, 0
+  br i1 %tobool, label %while.end, label %while.body
+
+while.end:                                        ; preds = %while.body, %entry
+  ret void
+; CHECK: loop:
+; CHECK-NOT: rdrandl
+; CHECK: This Inner Loop Header: Depth=1
+; CHECK: rdrandl
+}