if (MI.isNotDuplicable())
return false;
+ // Convergent instructions can be duplicated only if doing so doesn't add
+ // new control dependencies, which is what we're going to do here.
+ if (MI.isConvergent())
+ return false;
+
// Do not duplicate 'return' instructions if this is a pre-regalloc run.
// A return may expand into a lot more instructions (e.g. reload of callee
// saved registers) after PEI.
--- /dev/null
+; RUN: llc -O2 -tail-dup-size=100 -enable-tail-merge=0 < %s | FileCheck %s
+target triple = "nvptx64-nvidia-cuda"
+
+declare void @foo()
+declare void @llvm.cuda.syncthreads()
+
+; syncthreads shouldn't be duplicated.
+; CHECK: .func call_syncthreads
+; CHECK: bar.sync
+; CHECK-NOT: bar.sync
+define void @call_syncthreads(i32* %a, i32* %b, i1 %cond, i1 %cond2) nounwind {
+ br i1 %cond, label %L1, label %L2
+ br i1 %cond2, label %Ret, label %L1
+Ret:
+ ret void
+L1:
+ store i32 0, i32* %a
+ br label %L42
+L2:
+ store i32 1, i32* %a
+ br label %L42
+L42:
+ call void @llvm.cuda.syncthreads()
+ br label %Ret
+}
+
+; Check that call_syncthreads really does trigger tail duplication.
+; CHECK: .func call_foo
+; CHECK: call
+; CHECK: call
+define void @call_foo(i32* %a, i32* %b, i1 %cond, i1 %cond2) nounwind {
+ br i1 %cond, label %L1, label %L2
+ br i1 %cond2, label %Ret, label %L1
+Ret:
+ ret void
+L1:
+ store i32 0, i32* %a
+ br label %L42
+L2:
+ store i32 1, i32* %a
+ br label %L42
+L42:
+ call void @foo()
+ br label %Ret
+}