[LLD][COFF] Sort base relocations (#121699)

This change ensures that base relocations are sorted in the output,
aligning with MSVC linker behavior. While input files typically provide
sorted relocations, this update guarantees correct sorting even if the
input relocations are unordered.

Author: cjacek

lld/COFF/Writer.cpp

@@ -2560,6 +2560,8 @@ void Writer::addBaserelBlocks(std::vector<Baserel> &v) {
   const uint32_t mask = ~uint32_t(pageSize - 1);
   uint32_t page = v[0].rva & mask;
   size_t i = 0, j = 1;
+  llvm::sort(v,
+             [](const Baserel &x, const Baserel &y) { return x.rva < y.rva; });
   for (size_t e = v.size(); j < e; ++j) {
     uint32_t p = v[j].rva & mask;
     if (p == page)

lld/test/COFF/baserel-sort.yaml

@@ -0,0 +1,77 @@
+# Verify that lld-link outputs sorted base relocations, even if the input file has unsorted entries.
+
+# RUN: yaml2obj %s -o %t.obj
+# RUN: lld-link -dll -entry:sym -machine:amd64 -out:%t.dll %t.obj
+# RUN: llvm-readobj --coff-basereloc %t.dll | FileCheck %s
+
+# CHECK:      BaseReloc [
+# CHECK-NEXT:   Entry {
+# CHECK-NEXT:     Type: DIR64
+# CHECK-NEXT:     Address: 0x2000
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Entry {
+# CHECK-NEXT:     Type: DIR64
+# CHECK-NEXT:     Address: 0x2008
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Entry {
+# CHECK-NEXT:     Type: DIR64
+# CHECK-NEXT:     Address: 0x2010
+# CHECK-NEXT:   }
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     C3
+    SizeOfRawData:   1
+  - Name:            .test
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       1
+    SectionData:     '000000000000000000000000000000000000000000000000'
+    SizeOfRawData:   24
+    Relocations:
+      - VirtualAddress:  16
+        SymbolName:      sym
+        Type:            IMAGE_REL_AMD64_ADDR64
+      - VirtualAddress:  0
+        SymbolName:      sym
+        Type:            IMAGE_REL_AMD64_ADDR64
+      - VirtualAddress:  8
+        SymbolName:      sym
+        Type:            IMAGE_REL_AMD64_ADDR64
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .test
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          24
+      NumberOfRelocations: 3
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          2
+  - Name:            sym
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...