[Stackmap] Liveness Analysis Pass

This optional register liveness analysis pass can be enabled with either
-enable-stackmap-liveness, -enable-patchpoint-liveness, or both. The pass
traverses each basic block in a machine function. For each basic block the
instructions are processed in reversed order and if a patchpoint or stackmap
instruction is encountered the current live-out register set is encoded as a
register mask and attached to the instruction.

Later on during stackmap generation the live-out register mask is processed and
also emitted as part of the stackmap.

This information is optional and intended for optimization purposes only. This
will enable a client of the stackmap to reason about the registers it can use
and which registers need to be preserved.

Reviewed by Andy

llvm-svn: 197317

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 1eb590b55f8..e58856f024f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6886,6 +6886,9 @@ void SelectionDAGBuilder::visitStackmap(const CallInst &CI) {
   DAG.ReplaceAllUsesWith(Call, MN);
 
   DAG.DeleteNode(Call);
+
+  // Inform the Frame Information that we have a stackmap in this function.
+  FuncInfo.MF->getFrameInfo()->setHasStackMap();
 }
 
 /// \brief Lower llvm.experimental.patchpoint directly to its target opcode.
@@ -7025,6 +7028,9 @@ void SelectionDAGBuilder::visitPatchpoint(const CallInst &CI) {
   } else
     DAG.ReplaceAllUsesWith(Call, MN);
   DAG.DeleteNode(Call);
+
+  // Inform the Frame Information that we have a patchpoint in this function.
+  FuncInfo.MF->getFrameInfo()->setHasPatchPoint();
 }
 
 /// TargetLowering::LowerCallTo - This is the default LowerCallTo