[llvm] r201177 - R600/SI: Fix assertion on infinite loops.

[Matt Arsenault]

Author: arsenm
Date: Tue Feb 11 15:12:38 2014
New Revision: 201177

URL: http://llvm.org/viewvc/llvm-project?rev=201177&view=rev
Log:
R600/SI: Fix assertion on infinite loops.

This isn't the most useful case to fix in the real world,
but bugpoint runs into this.

Added:
    llvm/trunk/test/CodeGen/R600/infinite-loop.ll
Modified:
    llvm/trunk/lib/Target/R600/SILowerControlFlow.cpp

Modified: llvm/trunk/lib/Target/R600/SILowerControlFlow.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/R600/SILowerControlFlow.cpp?rev=201177&r1=201176&r2=201177&view=diff
==============================================================================
--- llvm/trunk/lib/Target/R600/SILowerControlFlow.cpp (original)
+++ llvm/trunk/lib/Target/R600/SILowerControlFlow.cpp Tue Feb 11 15:12:38 2014
@@ -283,8 +283,10 @@ void SILowerControlFlowPass::EndCf(Machi
 }
 
 void SILowerControlFlowPass::Branch(MachineInstr &MI) {
-  assert(MI.getOperand(0).getMBB() == MI.getParent()->getNextNode());
-  MI.eraseFromParent();
+  if (MI.getOperand(0).getMBB() == MI.getParent()->getNextNode())
+    MI.eraseFromParent();
+
+  // If these aren't equal, this is probably an infinite loop.
 }
 
 void SILowerControlFlowPass::Kill(MachineInstr &MI) {

Added: llvm/trunk/test/CodeGen/R600/infinite-loop.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/R600/infinite-loop.ll?rev=201177&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/R600/infinite-loop.ll (added)
+++ llvm/trunk/test/CodeGen/R600/infinite-loop.ll Tue Feb 11 15:12:38 2014
@@ -0,0 +1,17 @@
+; RUN: llc -march=r600 -mcpu=SI -verify-machineinstrs < %s | FileCheck -check-prefix=SI %s
+
+; SI-LABEL: @infinite_loop:
+; SI: V_MOV_B32_e32 [[REG:v[0-9]+]], 999
+; SI: BB0_1:
+; SI: BUFFER_STORE_DWORD [[REG]]
+; SI: S_WAITCNT vmcnt(0) expcnt(0)
+; SI: S_BRANCH BB0_1
+define void @infinite_loop(i32 addrspace(1)* %out) {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  store i32 999, i32 addrspace(1)* %out, align 4
+  br label %for.body
+}
+