[yaml2obj] Set p_align to the maximum sh_addralign of contained sections

The address difference between two sections in a PT_LOAD is a constant.
Consider a hypothetical case (pagesize can be very small, say, 4).

```
.text     sh_addralign=4
.text.hot sh_addralign=16
```

If we set p_align to 4, the PT_LOAD will be loaded at an address which
is a multiple of 4. The address of .text.hot is guaranteed to be a
multiple of 4, but not necessarily a multiple of 16.

This patch deletes the constraint

  if (SHeader->sh_offset == PHeader.p_offset)

Reviewed By: grimar, jhenderson

Differential Revision: https://reviews.llvm.org/D67260

llvm-svn: 371501

1 files changed, 4 insertions, 5 deletions

diff --git a/llvm/lib/ObjectYAML/ELFEmitter.cpp b/llvm/lib/ObjectYAML/ELFEmitter.cpp
index 531f0d4f1d8..72063a5dafd 100644
--- a/llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -645,16 +645,15 @@ void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
     PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
                                        : MemOffset - PHeader.p_offset;
 
-    // Set the alignment of the segment to be the same as the maximum alignment
-    // of the sections with the same offset so that by default the segment
-    // has a valid and sensible alignment.
     if (YamlPhdr.Align) {
       PHeader.p_align = *YamlPhdr.Align;
     } else {
+      // Set the alignment of the segment to be the maximum alignment of the
+      // sections so that by default the segment has a valid and sensible
+      // alignment.
       PHeader.p_align = 1;
       for (Elf_Shdr *SHeader : Sections)
-        if (SHeader->sh_offset == PHeader.p_offset)
-          PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
+        PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
     }
   }
 }