IPRA: Don't crash on null getCallPreservedMask

Kernels aren't callable, so they don't have a call preserved mask.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310172 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/RegUsageInfoCollector.cpp

@@ -128,9 +128,11 @@ bool RegUsageInfoCollector::runOnMachineFunction(MachineFunction &MF) {
   if (!TargetFrameLowering::isSafeForNoCSROpt(F)) {
     const uint32_t *CallPreservedMask =
         TRI->getCallPreservedMask(MF, F->getCallingConv());
-    // Set callee saved register as preserved.
-    for (unsigned i = 0; i < RegMaskSize; ++i)
-      RegMask[i] = RegMask[i] | CallPreservedMask[i];
+    if (CallPreservedMask) {
+      // Set callee saved register as preserved.
+      for (unsigned i = 0; i < RegMaskSize; ++i)
+        RegMask[i] = RegMask[i] | CallPreservedMask[i];
+    }
   } else {
     ++NumCSROpt;
     DEBUG(dbgs() << MF.getName()

test/CodeGen/AMDGPU/ipra.ll

@@ -0,0 +1,12 @@
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -verify-machineinstrs -enable-ipra < %s | FileCheck -check-prefix=GCN %s
+
+; Kernels are not called, so there is no call preserved mask.
+; GCN-LABEL: {{^}}kernel:
+; GCN: flat_store_dword
+define amdgpu_kernel void @kernel(i32 addrspace(1)* %out) #0 {
+entry:
+  store i32 0, i32 addrspace(1)* %out
+  ret void
+}
+
+attributes #0 = { nounwind }