[XCOFF] Ensure .file is emitted before any .info pseudo-ops (#71577)

When generating the assembly code for AIX/XCOFF, the .file pseudo-op
needs to be emitted first, before any csects are generated. Otherwise,
information such as the embedded command line will be associated with
part of the object file rather than the entire object file.

Author: stephenpeckham

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -443,7 +443,12 @@ bool AsmPrinter::doInitialization(Module &M) {
   const_cast<TargetLoweringObjectFile &>(getObjFileLowering())
       .getModuleMetadata(M);
 
-  OutStreamer->initSections(false, *TM.getMCSubtargetInfo());
+  // On AIX, we delay emitting any section information until
+  // after emitting the .file pseudo-op.  This allows additional
+  // information (such as the embedded command line) to be associated
+  // with all sections in the object file rather than a single section.
+  if (!TM.getTargetTriple().isOSBinFormatXCOFF())
+    OutStreamer->initSections(false, *TM.getMCSubtargetInfo());
 
   // Emit the version-min deployment target directive if needed.
   //
@@ -489,8 +494,11 @@ bool AsmPrinter::doInitialization(Module &M) {
 
   // On AIX, emit bytes for llvm.commandline metadata after .file so that the
   // C_INFO symbol is preserved if any csect is kept by the linker.
-  if (TM.getTargetTriple().isOSBinFormatXCOFF())
+  if (TM.getTargetTriple().isOSBinFormatXCOFF()) {
     emitModuleCommandLines(M);
+    // Now we can generate section information
+    OutStreamer->initSections(false, *TM.getMCSubtargetInfo());
+  }
 
   GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
   assert(MI && "AsmPrinter didn't require GCModuleInfo?");

llvm/test/CodeGen/PowerPC/aix-xcoff-data.ll

@@ -45,8 +45,8 @@
 
 ; CHECK-NOT: .toc
 
-; CHECK:      .csect [PR],5
-; CHECK-NEXT:  .file
+; CHECK:  .file
+; CHECK-NEXT:      .csect [PR],5
 
 ; CHECK:      .csect .data[RW],5
 ; CHECK-NEXT: .globl  ivar

llvm/test/DebugInfo/XCOFF/empty.ll

@@ -35,8 +35,8 @@ entry:
 !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
 !12 = !DILocation(line: 3, column: 3, scope: !8)
 
-; ASM32:               .csect [PR],5
-; ASM32-NEXT:          .file   "1.c"
+; ASM32:               .file   "1.c"
+; ASM32-NEXT:          .csect [PR],5
 ; ASM32-NEXT:          .globl  main[DS]                        # -- Begin function main
 ; ASM32-NEXT:          .globl  .main
 ; ASM32-NEXT:          .align  2
@@ -236,8 +236,8 @@ entry:
 ; ASM32-NEXT:          .byte   1
 ; ASM32-NEXT:  L..debug_line_end0:
 
-; ASM64:               .csect [PR],5
-; ASM64-NEXT:          .file   "1.c"
+; ASM64:               .file   "1.c"
+; ASM64-NEXT:          .csect [PR],5
 ; ASM64-NEXT:          .globl  main[DS]                        # -- Begin function main
 ; ASM64-NEXT:          .globl  .main
 ; ASM64-NEXT:          .align  2

llvm/test/DebugInfo/XCOFF/explicit-section.ll

@@ -42,8 +42,8 @@ entry:
 !15 = !DILocation(line: 3, column: 10, scope: !14)
 !16 = !DILocation(line: 3, column: 3, scope: !14)
 
-; CHECK:               .csect [PR],5
-; CHECK-NEXT:          .file   "2.c"
+; CHECK:               .file   "2.c"
+; CHECK-NEXT:          .csect [PR],5
 ; CHECK-NEXT:          .globl  bar[DS]                         # -- Begin function bar
 ; CHECK-NEXT:          .globl  .bar
 ; CHECK-NEXT:          .align  2

llvm/test/DebugInfo/XCOFF/function-sections.ll

@@ -37,8 +37,8 @@ entry:
 !13 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 6, type: !9, scopeLine: 7, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
 !14 = !DILocation(line: 8, column: 3, scope: !13)
 
-; CHECK:               .csect [PR],5
-; CHECK-NEXT:          .file   "1.c"
+; CHECK:               .file   "1.c"
+; CHECK-NEXT:          .csect [PR],5
 ; CHECK-NEXT:          .csect .foo[PR],5
 ; CHECK-NEXT:          .globl  foo[DS]                         # -- Begin function foo
 ; CHECK-NEXT:          .globl  .foo[PR]