[NVPTX] Use different, convergent MIs for convergent calls.

Summary:
Calls sometimes need to be convergent.  This is already handled at the
LLVM IR level, but it also needs to be handled at the MI level.

Ideally we'd propagate convergence from instructions, down through the
selection DAG, and into MIs.  But this is Hard, and would affect
optimizations in the SDNs -- right now only SDNs with two operands have
any flags at all.

Instead, here's a much simpler hack: Add new opcodes for NVPTX for
convergent calls, and generate these when lowering convergent LLVM
calls.

Reviewers: jholewinski

Subscribers: jholewinski, chandlerc, joker.eph, jhen, tra, llvm-commits

Differential Revision: http://reviews.llvm.org/D17423

llvm-svn: 262373

1 files changed, 27 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/NVPTX/convergent-mir-call.ll b/llvm/test/CodeGen/NVPTX/convergent-mir-call.ll
new file mode 100644
index 00000000000..18142450490
--- /dev/null
+++ b/llvm/test/CodeGen/NVPTX/convergent-mir-call.ll
@@ -0,0 +1,27 @@
+; RUN: llc -mtriple nvptx64-nvidia-cuda -stop-after machine-cp -o - < %s 2>&1 | FileCheck %s
+
+; Check that convergent calls are emitted using convergent MIR instructions,
+; while non-convergent calls are not.
+
+target triple = "nvptx64-nvidia-cuda"
+
+declare void @conv() convergent
+declare void @not_conv()
+
+define void @test(void ()* %f) {
+  ; CHECK: ConvergentCallUniPrintCall
+  ; CHECK-NEXT: @conv
+  call void @conv()
+
+  ; CHECK: CallUniPrintCall
+  ; CHECK-NEXT: @not_conv
+  call void @not_conv()
+
+  ; CHECK: ConvergentCallPrintCall
+  call void %f() convergent
+
+  ; CHECK: CallPrintCall
+  call void %f()
+
+  ret void
+}