[PATCH] D46420: Object: The default alignment of a section without alignment flags is 16.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc created this revision.
pcc added reviewers: ruiu, hans.

Depends on https://reviews.llvm.org/D46419


https://reviews.llvm.org/D46420

Files:
  lld/test/COFF/default-alignment.test
  llvm/include/llvm/Object/COFF.h


Index: llvm/include/llvm/Object/COFF.h
===================================================================
--- llvm/include/llvm/Object/COFF.h
+++ llvm/include/llvm/Object/COFF.h
@@ -452,11 +452,12 @@
     if (Characteristics & COFF::IMAGE_SCN_TYPE_NO_PAD)
       return 1;
 
-    // Bit [20:24] contains section alignment. Both 0 and 1 mean alignment 1.
+    // Bit [20:24] contains section alignment. 0 means use a default alignment
+    // of 16.
     uint32_t Shift = (Characteristics >> 20) & 0xF;
     if (Shift > 0)
       return 1U << (Shift - 1);
-    return 1;
+    return 16;
   }
 };
 
Index: lld/test/COFF/default-alignment.test
===================================================================
--- /dev/null
+++ lld/test/COFF/default-alignment.test
@@ -0,0 +1,21 @@
+# RUN: yaml2obj < %s > %t.obj
+# RUN: lld-link /out:%t.exe %t.obj /entry:__ImageBase /subsystem:console
+# RUN: llvm-objdump -s %t.exe | FileCheck %s
+
+# CHECK: Contents of section .rdata:
+# CHECK-NEXT: 01000000 00000000 00000000 00000000
+# CHECK-NEXT: 02
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    SectionData:     01
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    SectionData:     02
+symbols:
+...


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