BranchRelaxation: Support expanding unconditional branches

AMDGPU needs to expand unconditional branches in a new
block with an indirect branch.

llvm-svn: 283464

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUAsmPrinter.cpp b/llvm/lib/Target/AMDGPU/AMDGPUAsmPrinter.cpp
index ef7321402da..ef20047377f 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUAsmPrinter.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUAsmPrinter.cpp
@@ -120,6 +120,21 @@ void AMDGPUAsmPrinter::EmitStartOfAsmFile(Module &M) {
   emitStartOfRuntimeMetadata(M);
 }
 
+bool AMDGPUAsmPrinter::isBlockOnlyReachableByFallthrough(
+  const MachineBasicBlock *MBB) const {
+  if (!AsmPrinter::isBlockOnlyReachableByFallthrough(MBB))
+    return false;
+
+  if (MBB->empty())
+    return true;
+
+  // If this is a block implementing a long branch, an expression relative to
+  // the start of the block is needed.  to the start of the block.
+  // XXX - Is there a smarter way to check this?
+  return (MBB->back().getOpcode() != AMDGPU::S_SETPC_B64);
+}
+
+
 void AMDGPUAsmPrinter::EmitFunctionBodyStart() {
   const AMDGPUSubtarget &STM = MF->getSubtarget<AMDGPUSubtarget>();
   SIProgramInfo KernelInfo;