diff options
| -rw-r--r-- | llvm/lib/CodeGen/TailDuplication.cpp | 5 | ||||
| -rw-r--r-- | llvm/test/CodeGen/NVPTX/TailDuplication-convergent.ll | 45 |
2 files changed, 50 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/TailDuplication.cpp b/llvm/lib/CodeGen/TailDuplication.cpp index c2c7a1a3d92..da593ce3717 100644 --- a/llvm/lib/CodeGen/TailDuplication.cpp +++ b/llvm/lib/CodeGen/TailDuplication.cpp @@ -590,6 +590,11 @@ TailDuplicatePass::shouldTailDuplicate(const MachineFunction &MF, 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. diff --git a/llvm/test/CodeGen/NVPTX/TailDuplication-convergent.ll b/llvm/test/CodeGen/NVPTX/TailDuplication-convergent.ll new file mode 100644 index 00000000000..02b562d85b9 --- /dev/null +++ b/llvm/test/CodeGen/NVPTX/TailDuplication-convergent.ll @@ -0,0 +1,45 @@ +; 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 +} |
