Index: lib/Target/R600/AMDGPUTargetMachine.cpp
===================================================================
--- lib/Target/R600/AMDGPUTargetMachine.cpp
+++ lib/Target/R600/AMDGPUTargetMachine.cpp
@@ -145,6 +145,11 @@
   if (ST.getGeneration() >= AMDGPUSubtarget::SOUTHERN_ISLANDS) {
     addPass(createSinkingPass());
     addPass(createSITypeRewriter());
+
+    // Run SimplifyCFG to make sure we have no branches on constants and other
+    // edge cases to deal with before annotating control flow. These seem to
+    // survive here on occasion.
+    addPass(createCFGSimplificationPass());
     addPass(createSIAnnotateControlFlowPass());
   } else {
     addPass(createR600TextureIntrinsicsReplacer());
Index: test/CodeGen/R600/cf-empty-stack-assert.ll
===================================================================
--- /dev/null
+++ test/CodeGen/R600/cf-empty-stack-assert.ll
@@ -0,0 +1,23 @@
+; REQUIRES: asserts
+; XFAIL: *
+; RUN: llc -verify-machineinstrs -march=r600 -mcpu=SI < %s | FileCheck -check-prefix=SI %s
+
+; SI-LABEL: @loop_arg_1
+define void @loop_arg_1(float addrspace(3)* %ptr, i32 %n, i1 %cond) nounwind {
+entry:
+  br i1 %cond, label %for.body, label %for.exit
+
+for.exit:
+  ret void
+
+for.body:
+  %indvar = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %tmp = add i32 %indvar, 32
+  %arrayidx = getelementptr float addrspace(3)* %ptr, i32 %tmp
+  %vecload = load float addrspace(3)* %arrayidx, align 4
+  %add = fadd float %vecload, 1.0
+  store float %add, float addrspace(3)* %arrayidx, align 8
+  %inc = add i32 %indvar, 1
+  %cmp = icmp eq i32 %inc, 10000
+  br i1 %cmp, label %for.body, label %for.exit
+}
Index: test/CodeGen/R600/cf-loop-on-constant.ll
===================================================================
--- /dev/null
+++ test/CodeGen/R600/cf-loop-on-constant.ll
@@ -0,0 +1,120 @@
+; RUN: llc -march=r600 -mcpu=SI < %s | FileCheck -check-prefix=SI %s
+
+; FIXME: Fails with -verify-machineinstrs
+
+; SI-LABEL: @test_loop
+; SI: [[LABEL:BB[0-9+]_[0-9]+]]:
+; SI: DS_READ_B32
+; SI: DS_WRITE_B32
+; SI: S_BRANCH [[LABEL]]
+; SI: S_ENDPGM
+define void @test_loop(float addrspace(3)* %ptr, i32 %n) nounwind {
+entry:
+  %cmp = icmp eq i32 %n, -1
+  br i1 %cmp, label %for.exit, label %for.body
+
+for.exit:
+  ret void
+
+for.body:
+  %indvar = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %tmp = add i32 %indvar, 32
+  %arrayidx = getelementptr float addrspace(3)* %ptr, i32 %tmp
+  %vecload = load float addrspace(3)* %arrayidx, align 4
+  %add = fadd float %vecload, 1.0
+  store float %add, float addrspace(3)* %arrayidx, align 8
+  %inc = add i32 %indvar, 1
+  br label %for.body
+}
+
+; XXX - This needs to be tested at -O0, but that hits a different problem.
+; XXX - Does this need an S_ENDPGM?
+
+; SI-LABEL: @loop_const_true
+; SI: [[LABEL:BB[0-9+]_[0-9]+]]:
+; SI: DS_READ_B32
+; SI: DS_WRITE_B32
+; SI: S_BRANCH [[LABEL]]
+define void @loop_const_true(float addrspace(3)* %ptr, i32 %n) nounwind {
+entry:
+  br label %for.body
+
+for.exit:
+  ret void
+
+; XXX - Should there be an S_ENDPGM?
+for.body:
+  %indvar = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %tmp = add i32 %indvar, 32
+  %arrayidx = getelementptr float addrspace(3)* %ptr, i32 %tmp
+  %vecload = load float addrspace(3)* %arrayidx, align 4
+  %add = fadd float %vecload, 1.0
+  store float %add, float addrspace(3)* %arrayidx, align 8
+  %inc = add i32 %indvar, 1
+  br i1 true, label %for.body, label %for.exit
+}
+
+; SI-LABEL: @loop_const_false
+; SI-NOT: S_BRANCH
+; SI: S_ENDPGM
+define void @loop_const_false(float addrspace(3)* %ptr, i32 %n) nounwind {
+entry:
+  br label %for.body
+
+for.exit:
+  ret void
+
+; XXX - Should there be an S_ENDPGM?
+for.body:
+  %indvar = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %tmp = add i32 %indvar, 32
+  %arrayidx = getelementptr float addrspace(3)* %ptr, i32 %tmp
+  %vecload = load float addrspace(3)* %arrayidx, align 4
+  %add = fadd float %vecload, 1.0
+  store float %add, float addrspace(3)* %arrayidx, align 8
+  %inc = add i32 %indvar, 1
+  br i1 false, label %for.body, label %for.exit
+}
+
+; SI-LABEL: @loop_const_undef
+; SI-NOT: S_BRANCH
+; SI: S_ENDPGM
+define void @loop_const_undef(float addrspace(3)* %ptr, i32 %n) nounwind {
+entry:
+  br label %for.body
+
+for.exit:
+  ret void
+
+; XXX - Should there be an S_ENDPGM?
+for.body:
+  %indvar = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %tmp = add i32 %indvar, 32
+  %arrayidx = getelementptr float addrspace(3)* %ptr, i32 %tmp
+  %vecload = load float addrspace(3)* %arrayidx, align 4
+  %add = fadd float %vecload, 1.0
+  store float %add, float addrspace(3)* %arrayidx, align 8
+  %inc = add i32 %indvar, 1
+  br i1 undef, label %for.body, label %for.exit
+}
+
+; SI-LABEL: @loop_arg_0
+; SI: S_CBRANCH_EXECNZ
+define void @loop_arg_0(float addrspace(3)* %ptr, i32 %n, i1 %cond) nounwind {
+entry:
+  br label %for.body
+
+for.exit:
+  ret void
+
+for.body:
+  %indvar = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %tmp = add i32 %indvar, 32
+  %arrayidx = getelementptr float addrspace(3)* %ptr, i32 %tmp
+  %vecload = load float addrspace(3)* %arrayidx, align 4
+  %add = fadd float %vecload, 1.0
+  store float %add, float addrspace(3)* %arrayidx, align 8
+  %inc = add i32 %indvar, 1
+  br i1 %cond, label %for.body, label %for.exit
+}
+