AMDGPU/SI: Incomplete shader binaries need to finish execution at the end

Reviewers: tstellarAMD, arsenm

Subscribers: arsenm

Differential Revision: http://reviews.llvm.org/D18058

llvm-svn: 263441

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp b/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp
index edcfb0889bb..7dd0d7bc8f7 100644
--- a/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp
+++ b/llvm/lib/Target/AMDGPU/SILowerControlFlow.cpp
@@ -486,6 +486,7 @@ bool SILowerControlFlow::runOnMachineFunction(MachineFunction &MF) {
   for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
        BI != BE; ++BI) {
 
+    MachineBasicBlock *EmptyMBBAtEnd = NULL;
     MachineBasicBlock &MBB = *BI;
     MachineBasicBlock::iterator I, Next;
     for (I = MBB.begin(); I != MBB.end(); I = Next) {
@@ -562,6 +563,29 @@ bool SILowerControlFlow::runOnMachineFunction(MachineFunction &MF) {
         case AMDGPU::SI_INDIRECT_DST_V16:
           IndirectDst(MI);
           break;
+
+        case AMDGPU::S_ENDPGM: {
+          if (MF.getInfo<SIMachineFunctionInfo>()->returnsVoid())
+            break;
+
+          // Graphics shaders returning non-void shouldn't contain S_ENDPGM,
+          // because external bytecode will be appended at the end.
+          if (BI != --MF.end() || I != MBB.getFirstTerminator()) {
+            // S_ENDPGM is not the last instruction. Add an empty block at
+            // the end and jump there.
+            if (!EmptyMBBAtEnd) {
+              EmptyMBBAtEnd = MF.CreateMachineBasicBlock();
+              MF.insert(MF.end(), EmptyMBBAtEnd);
+            }
+
+            MBB.addSuccessor(EmptyMBBAtEnd);
+            BuildMI(*BI, I, MI.getDebugLoc(), TII->get(AMDGPU::S_BRANCH))
+                    .addMBB(EmptyMBBAtEnd);
+          }
+
+          I->eraseFromParent();
+          break;
+        }
       }
     }
   }