COFF: Merge .xdata into .rdata by default.

[pcc]

Summary

Depends on D45801

[ruiu]

LGTM

lld/COFF/Driver.cpp

void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   for (auto *Arg : Args.filtered(OPT_merge))
     parseMerge(Arg->getValue());
 
   // Add default section merging rules after user rules. User rules take
   // precedence, but we will emit a warning if there is a conflict.
   parseMerge(".idata=.rdata");
   parseMerge(".didat=.rdata");
   parseMerge(".edata=.rdata");
+  parseMerge(".xdata=.rdata");
   parseMerge(".bss=.data");
 
   // Handle /section
   for (auto *Arg : Args.filtered(OPT_section))
     parseSection(Arg->getValue());
 
   // Handle /aligncomm
   for (auto *Arg : Args.filtered(OPT_aligncomm))

lld/test/COFF/icf-xdata.s

 # RUN: llvm-mc %s -triple x86_64-windows-msvc -filetype=obj -o %t.obj
+# RUN: lld-link %t.obj -dll -noentry -out:%t.dll -merge:.xdata=.xdata 2>&1 \
+# RUN:     | FileCheck %s --check-prefix=WARN
+# RUN: llvm-readobj -sections %t.dll | FileCheck %s --check-prefix=XDATA
 # RUN: lld-link %t.obj -dll -noentry -out:%t.dll
-# RUN: llvm-readobj -sections %t.dll | FileCheck %s
+# RUN: llvm-readobj -sections %t.dll | FileCheck %s --check-prefix=RDATA
 
 # There shouldn't be much xdata, because all three .pdata entries (12 bytes
 # each) should use the same .xdata unwind info.
-# CHECK:         Name: .pdata
-# CHECK-NEXT:    VirtualSize: 0x24
-# CHECK:         Name: .xdata
-# CHECK-NEXT:    VirtualSize: 0x8
+# XDATA:         Name: .rdata
+# XDATA-NEXT:    VirtualSize: 0x73
+# XDATA:         Name: .pdata
+# XDATA-NEXT:    VirtualSize: 0x24
+# XDATA:         Name: .xdata
+# XDATA-NEXT:    VirtualSize: 0x8
+#
+# WARN: warning: .xdata=.rdata: already merged into .xdata
+#
+# RDATA:         Name: .rdata
+# RDATA-NEXT:    VirtualSize: 0x7C
+# RDATA:         Name: .pdata
+# RDATA-NEXT:    VirtualSize: 0x24
 
   .text
 callee:
   ret
 
   .def   xdata1;
   .scl  2;
   .type 32;

lld/test/COFF/pdb.test

 RAW-NEXT:       800 file pointer to raw data
 RAW-NEXT:         0 file pointer to relocation table
 RAW-NEXT:         0 file pointer to line numbers
 RAW-NEXT:         0 number of relocations
 RAW-NEXT:         0 number of line numbers
 RAW-NEXT:  40000040 flags
 RAW-NEXT:           IMAGE_SCN_CNT_INITIALIZED_DATA
 RAW-NEXT:           IMAGE_SCN_MEM_READ
-RAW:        SECTION HEADER #4
-RAW-NEXT:    .xdata name
-RAW-NEXT:         8 virtual size
-RAW-NEXT:      4000 virtual address
-RAW-NEXT:       200 size of raw data
-RAW-NEXT:       A00 file pointer to raw data
-RAW-NEXT:         0 file pointer to relocation table
-RAW-NEXT:         0 file pointer to line numbers
-RAW-NEXT:         0 number of relocations
-RAW-NEXT:         0 number of line numbers
-RAW-NEXT:  40000040 flags
-RAW-NEXT:           IMAGE_SCN_CNT_INITIALIZED_DATA
-RAW-NEXT:           IMAGE_SCN_MEM_READ
 RAW:                        Original Section Headers
 RAW-NEXT: ============================================================
 RAW-NEXT:   PDB does not contain the requested image section header type
 RAW:                        Section Contributions
 RAW-NEXT: ============================================================
 
 RAW-NEXT:   SC[.text]   | mod = 0, 0001:0000, size = 14, data crc = 1682752513, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_CODE | IMAGE_SCN_ALIGN_16BYTES | IMAGE_SCN_MEM_EXECUTE |
 RAW-NEXT:                 IMAGE_SCN_MEM_READ
 RAW-NEXT:   SC[.text]   | mod = 1, 0001:0016, size = 6, data crc = 2139436471, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_CODE | IMAGE_SCN_ALIGN_16BYTES | IMAGE_SCN_MEM_EXECUTE |
 RAW-NEXT:                 IMAGE_SCN_MEM_READ
 RAW-NEXT:   SC[.rdata]  | mod = 2, 0002:0000, size = {{[0-9]+}}, data crc = 0, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ
 RAW-NEXT:   SC[.rdata]  | mod = 2, 0002:0028, size = {{[0-9]+}}, data crc = 0, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ
-RAW-NEXT:   SC[.pdata]  | mod = 0, 0003:0000, size = 12, data crc = 361370162, reloc crc = 0
+RAW-NEXT:   SC[.rdata]  | mod = 0, 0002:0148, size = {{[0-9]+}}, data crc = 264583633, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_MEM_READ
-RAW-NEXT:   SC[.xdata]  | mod = 0, 0004:0000, size = {{[0-9]+}}, data crc = 264583633, reloc crc = 0
+RAW-NEXT:   SC[.pdata]  | mod = 0, 0003:0000, size = 12, data crc = 361370162, reloc crc = 0
 RAW-NEXT:                 IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_MEM_READ
 RAW-NOT: SC[
 RAW:                             Section Map
 RAW-NEXT: ============================================================
 
 RAW-NEXT:   Section 0000 | ovl = 0, group = 0, frame = 1, name = 65535
 RAW-NEXT:                  class = 65535, offset = 0, size =
 RAW-NEXT:                  flags = read | execute | 32 bit addr | selector
 RAW-NEXT:   Section 0001 | ovl = 0, group = 0, frame = 2, name = 65535
 RAW-NEXT:                  class = 65535, offset = 0, size =
 RAW-NEXT:                  flags = read | 32 bit addr | selector
 RAW-NEXT:   Section 0002 | ovl = 0, group = 0, frame = 3, name = 65535
 RAW-NEXT:                  class = 65535, offset = 0, size =
 RAW-NEXT:                  flags = read | 32 bit addr | selector
 RAW-NEXT:   Section 0003 | ovl = 0, group = 0, frame = 4, name = 65535
-RAW-NEXT:                  class = 65535, offset = 0, size =
-RAW-NEXT:                  flags = read | 32 bit addr | selector
-RAW-NEXT:   Section 0004 | ovl = 0, group = 0, frame = 5, name = 65535
 RAW-NEXT:                  class = 65535, offset = 0, size = 4294967295
 RAW-NEXT:                  flags = 32 bit addr | absolute addr

lld/test/COFF/unwind.test

 # HEADER: ExceptionTableRVA: 0x3000
 #
 # FIXME: llvm-readobj currently does not understand files with .pdata merged
 # into .rdata. But we can at least check that the section headers look correct.
 #
 # HEADER-MERGE: ExceptionTableRVA: 0x2004
 # HEADER-MERGE-NEXT: ExceptionTableSize: 0x30
 # HEADER-MERGE: Name: .rdata
-# HEADER-MERGE-NEXT: VirtualSize: 0x34
+# HEADER-MERGE-NEXT: VirtualSize: 0x78
 # HEADER-MERGE-NEXT: VirtualAddress: 0x2000
 #
 # UNWIND: Function Table:
 # UNWIND:   Start Address: 0x1000
 # UNWIND:   End Address: 0x101b
-# UNWIND:   Unwind Info Address: 0x4000
+# UNWIND:   Unwind Info Address: 0x2004
 # UNWIND:     Version: 1
 # UNWIND:     Flags: 1 UNW_ExceptionHandler
 # UNWIND:     Size of prolog: 18
 # UNWIND:     Number of Codes: 8
 # UNWIND:     Frame register: RBX
 # UNWIND:     Frame offset: 0
 # UNWIND:     Unwind Codes:
 # UNWIND:       0x12: UOP_SetFPReg
 # UNWIND:       0x0f: UOP_PushNonVol RBX
 # UNWIND:       0x0e: UOP_SaveXMM128 XMM8 [0x0000]
 # UNWIND:       0x09: UOP_SaveNonVol RSI [0x0010]
 # UNWIND:       0x04: UOP_AllocSmall 24
 # UNWIND:       0x00: UOP_PushMachFrame w/o error code
 # UNWIND: Function Table:
 # UNWIND:   Start Address: 0x1012
 # UNWIND:   End Address: 0x1012
-# UNWIND:   Unwind Info Address: 0x401c
+# UNWIND:   Unwind Info Address: 0x2020
 # UNWIND:     Version: 1
 # UNWIND:     Flags: 4 UNW_ChainInfo
 # UNWIND:     Size of prolog: 0
 # UNWIND:     Number of Codes: 0
 # UNWIND:     No frame pointer used
 # UNWIND: Function Table:
 # UNWIND:   Start Address: 0x101b
 # UNWIND:   End Address: 0x101c
-# UNWIND:   Unwind Info Address: 0x402c
+# UNWIND:   Unwind Info Address: 0x2030
 # UNWIND:     Version: 1
 # UNWIND:     Flags: 0
 # UNWIND:     Size of prolog: 0
 # UNWIND:     Number of Codes: 0
 # UNWIND:     No frame pointer used
 # UNWIND: Function Table:
 # UNWIND:   Start Address: 0x101c
 # UNWIND:   End Address: 0x1039
-# UNWIND:   Unwind Info Address: 0x4034
+# UNWIND:   Unwind Info Address: 0x2038
 # UNWIND:     Version: 1
 # UNWIND:     Flags: 0
 # UNWIND:     Size of prolog: 14
 # UNWIND:     Number of Codes: 6
 # UNWIND:     No frame pointer used
 # UNWIND:     Unwind Codes:
 # UNWIND:       0x0e: UOP_AllocLarge 8454128
 # UNWIND:       0x07: UOP_AllocLarge 8190