[X86] Fix MCNullStreamer support for modules with a CodeView flag

[eush]

Summary

This fixes -filetype=null support when compiling for a Win32 target
and the module has a CodeView flag.

The only places changed are the uses of getTargetStreamer function -
this patch guards both of them with null checks.

[RKSimon]

lib/Target/X86/X86AsmPrinter.cpp

92 ↗

(On Diff #172250)

(style) We normally do auto for cast cases like this as the type is obvious.

104 ↗

(On Diff #172250)

(style) We normally do auto for cast cases like this as the type is obvious.

[eush]

Fixed style.

[RKSimon]

LGTM

[eush]

Could you commit this patch on my behalf?

llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp

bool X86AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
   EmitFPOData = false;
 
   // We didn't modify anything.
   return false;
 }
 
 void X86AsmPrinter::EmitFunctionBodyStart() {
   if (EmitFPOData) {
-    X86TargetStreamer *XTS =
-        static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
-    unsigned ParamsSize =
-        MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize();
-    XTS->emitFPOProc(CurrentFnSym, ParamsSize);
+    if (auto *XTS =
+        static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
+      XTS->emitFPOProc(
+          CurrentFnSym,
+          MF->getInfo<X86MachineFunctionInfo>()->getArgumentStackSize());
   }
 }
 
 void X86AsmPrinter::EmitFunctionBodyEnd() {
   if (EmitFPOData) {
-    X86TargetStreamer *XTS =
-        static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer());
+    if (auto *XTS =
+            static_cast<X86TargetStreamer *>(OutStreamer->getTargetStreamer()))
       XTS->emitFPOEndProc();
   }
 }
 
 /// printSymbolOperand - Print a raw symbol reference operand.  This handles
 /// jump tables, constant pools, global address and external symbols, all of
 /// which print to a label with various suffixes for relocation types etc.
 static void printSymbolOperand(X86AsmPrinter &P, const MachineOperand &MO,
                                raw_ostream &O) {

llvm/trunk/test/CodeGen/X86/null-streamer.ll

 ; Check the MCNullStreamer operates correctly, at least on a minimal test case.
 ;
 ; RUN: llc -filetype=null -o %t -mtriple=i686-- %s
 ; RUN: llc -filetype=null -o %t -mtriple=i686-cygwin %s
 
 source_filename = "test/CodeGen/X86/null-streamer.ll"
 
 define void @f0() {
   ret void
 }
 
 define void @f1() {
   ret void
 }
 
 !llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!7, !8}
+!llvm.module.flags = !{!7, !8, !9}
 
 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: " ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !3, imports: !2)
 !1 = !DIFile(filename: "file.c", directory: "")
 !2 = !{}
 !3 = !{!4}
 !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
 !5 = !DIGlobalVariable(name: "i", linkageName: "_ZL1i", scope: null, file: !1, line: 1, type: !6, isLocal: true, isDefinition: true)
 !6 = !DIBasicType(size: 32, align: 32, encoding: DW_ATE_signed)
 !7 = !{i32 2, !"Dwarf Version", i32 3}
 !8 = !{i32 1, !"Debug Info Version", i32 3}
-
+!9 = !{i32 2, !"CodeView", i32 1}