[AIX][XCOFF] Fix XCOFFObjectWriter assertion failure with alignment-related gap and improve text section output testing

SUMMARY:
1.if there is a gap between the end virtual address of one section and the beginning virtual address of the next section, the XCOFFObjectWriter.cpp will hit a assert.

2.as discussed in the patch https://reviews.llvm.org/D66969,
since implemented the function description. We can output the raw object data for function.
we need to create a test for raw text section content and test section header for xcoff object file.

Reviewer: daltenty,hubert.reinterpretcast,jasonliu

Differential Revision: https://reviews.llvm.org/D71845

Author: diggerlin

llvm/lib/MC/XCOFFObjectWriter.cpp

@@ -439,8 +439,14 @@ void XCOFFObjectWriter::writeSections(const MCAssembler &Asm,
     if (Section->Index == Section::UninitializedIndex || Section->IsVirtual)
       continue;
 
-    assert(CurrentAddressLocation == Section->Address &&
-           "Sections should be written consecutively.");
+    // There could be a gap (without corresponding zero padding) between
+    // sections.
+    assert(CurrentAddressLocation <= Section->Address &&
+           "CurrentAddressLocation should be less than or equal to section "
+           "address.");
+
+    CurrentAddressLocation = Section->Address;
+
     for (const auto *Group : Section->Groups) {
       for (const auto &Csect : *Group) {
         if (uint32_t PaddingSize = Csect.Address - CurrentAddressLocation)

llvm/test/CodeGen/PowerPC/aix-return55.ll

@@ -1,5 +1,15 @@
-; RUN: llc -mcpu=pwr9 -mtriple=powerpc-ibm-aix-xcoff -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mcpu=pwr4 -mtriple=powerpc-ibm-aix-xcoff -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mcpu=pwr4 -mtriple=powerpc-ibm-aix-xcoff -verify-machineinstrs -filetype=obj -o %t.o < %s
+; RUN: llvm-objdump -D %t.o | FileCheck --check-prefix=CHECKOBJ %s
+; RUN: llvm-readobj -sections %t.o | FileCheck --check-prefix=CHECKSECT %s
 
+; RUN: not --crash llc -mtriple powerpc64-ibm-aix-xcoff -filetype=obj < %s 2>&1 | \
+; RUN: FileCheck --check-prefix=XCOFF64 %s
+; XCOFF64: LLVM ERROR: 64-bit XCOFF object files are not supported yet.
+
+@a = global i64 320255973571806, align 8
+@d = global double 5.000000e+00, align 8
+@strA = private unnamed_addr constant [10 x i8] c"hellowor\0A\00", align 1
 
 define dso_local signext i32 @foo() {
 entry:
@@ -9,3 +19,50 @@ entry:
 ; CHECK: blr
 }
 
+;CHECKOBJ:      00000000 .text:
+;CHECKOBJ-NEXT:       0: 38 60 00 37                    li 3, 55
+;CHECKOBJ-NEXT:       4: 4e 80 00 20                    blr{{[[:space:]] *}}
+;CHECKOBJ-NEXT: 00000008 .rodata.str1.1:
+;CHECKOBJ-NEXT:       8: 68 65 6c 6c                   xori 5, 3, 27756
+;CHECKOBJ-NEXT:       c: 6f 77 6f 72 xoris 23, 27, 28530
+;CHECKOBJ-NEXT:      10: 0a 00 00 00 tdlti 0, 0{{[[:space:]] *}}
+;CHECKOBJ-NEXT: Disassembly of section .data:{{[[:space:]] *}}
+;CHECKOBJ-NEXT: 00000018 a:
+;CHECKOBJ-NEXT:      18: 00 01 23 45                   <unknown>
+;CHECKOBJ-NEXT:      1c: 67 8a bc de                   oris 10, 28, 48350{{[[:space:]] *}}
+;CHECKOBJ-NEXT: 00000020 d:
+;CHECKOBJ-NEXT:      20: 40 14 00 00                   bdnzf   20, .+0
+;CHECKOBJ-NEXT:      24: 00 00 00 00                   <unknown>{{[[:space:]] *}}
+;CHECKOBJ-NEXT: 00000028 foo:
+;CHECKOBJ-NEXT:      28: 00 00 00 00                   <unknown>
+;CHECKOBJ-NEXT:      2c: 00 00 00 34                   <unknown>
+;CHECKOBJ-NEXT:      30: 00 00 00 00                   <unknown>
+
+;CHECKSECT: Sections [
+;CHECKSECT-NEXT:   Section {
+;CHECKSECT-NEXT:     Index: 1
+;CHECKSECT-NEXT:     Name: .text
+;CHECKSECT-NEXT:     PhysicalAddress: 0x0
+;CHECKSECT-NEXT:     VirtualAddress: 0x0
+;CHECKSECT-NEXT:     Size: 0x14
+;CHECKSECT-NEXT:     RawDataOffset: 0x64
+;CHECKSECT-NEXT:     RelocationPointer: 0x0
+;CHECKSECT-NEXT:     LineNumberPointer: 0x0
+;CHECKSECT-NEXT:     NumberOfRelocations: 0
+;CHECKSECT-NEXT:     NumberOfLineNumbers: 0
+;CHECKSECT-NEXT:     Type: STYP_TEXT (0x20)
+;CHECKSECT-NEXT:   }
+;CHECKSECT-NEXT:   Section {
+;CHECKSECT-NEXT:     Index: 2
+;CHECKSECT-NEXT:     Name: .data
+;CHECKSECT-NEXT:     PhysicalAddress: 0x18
+;CHECKSECT-NEXT:     VirtualAddress: 0x18
+;CHECKSECT-NEXT:     Size: 0x1C
+;CHECKSECT-NEXT:     RawDataOffset: 0x78
+;CHECKSECT-NEXT:     RelocationPointer: 0x94
+;CHECKSECT-NEXT:     LineNumberPointer: 0x0
+;CHECKSECT-NEXT:     NumberOfRelocations: 2
+;CHECKSECT-NEXT:     NumberOfLineNumbers: 0
+;CHECKSECT-NEXT:     Type: STYP_DATA (0x40)
+;CHECKSECT-NEXT:   }
+;CHECKSECT-NEXT: ]