[PATCH] D32749: [LLD][ELF] Fix problems with fabricateDefaultCommands() and --section-start

[Peter Smith via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL302007: [ELF] Fix problems with fabricateDefaultCommands() and --section-start (authored by psmith).

Changed prior to commit:
  https://reviews.llvm.org/D32749?vs=97445&id=97571#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D32749

Files:
  lld/trunk/ELF/LinkerScript.cpp
  lld/trunk/ELF/Writer.cpp
  lld/trunk/test/ELF/sectionstart-noallochdr.s


Index: lld/trunk/ELF/Writer.cpp
===================================================================
--- lld/trunk/ELF/Writer.cpp
+++ lld/trunk/ELF/Writer.cpp
@@ -252,7 +252,7 @@
   } else {
     if (!Script->Opt.HasSections) {
       fixSectionAlignments();
-      Script->fabricateDefaultCommands(Config->MaxPageSize);
+      Script->fabricateDefaultCommands(AllocateHeader);
     }
     Script->synchronize();
     Script->assignAddresses(Phdrs);
Index: lld/trunk/ELF/LinkerScript.cpp
===================================================================
--- lld/trunk/ELF/LinkerScript.cpp
+++ lld/trunk/ELF/LinkerScript.cpp
@@ -428,13 +428,12 @@
   if (AllocateHeader)
     StartAddr += elf::getHeaderSize();
 
-  // The Sections with -T<section> are sorted in order of ascending address
-  // we must use this if it is lower than StartAddr as calls to setDot() must
-  // be monotonically increasing
-  if (!Config->SectionStartMap.empty()) {
-    uint64_t LowestSecStart = Config->SectionStartMap.begin()->second;
-    StartAddr = std::min(StartAddr, LowestSecStart);
-  }
+  // The Sections with -T<section> have been sorted in order of ascending
+  // address. We must lower StartAddr if the lowest -T<section address> as
+  // calls to setDot() must be monotonically increasing.
+  for (auto& KV : Config->SectionStartMap)
+    StartAddr = std::min(StartAddr, KV.second);
+
   Commands.push_back(
       make<SymbolAssignment>(".", [=] { return StartAddr; }, ""));
 
@@ -444,17 +443,19 @@
     if (!(Sec->Flags & SHF_ALLOC))
       continue;
 
+    auto *OSCmd = make<OutputSectionCommand>(Sec->Name);
+    OSCmd->Sec = Sec;
+
+    // Prefer user supplied address over additional alignment constraint
     auto I = Config->SectionStartMap.find(Sec->Name);
     if (I != Config->SectionStartMap.end())
       Commands.push_back(
           make<SymbolAssignment>(".", [=] { return I->second; }, ""));
-
-    auto *OSCmd = make<OutputSectionCommand>(Sec->Name);
-    OSCmd->Sec = Sec;
-    if (Sec->PageAlign)
+    else if (Sec->PageAlign)
       OSCmd->AddrExpr = [=] {
         return alignTo(Script->getDot(), Config->MaxPageSize);
       };
+
     Commands.push_back(OSCmd);
     if (Sec->Sections.size()) {
       auto *ISD = make<InputSectionDescription>("");
Index: lld/trunk/test/ELF/sectionstart-noallochdr.s
===================================================================
--- lld/trunk/test/ELF/sectionstart-noallochdr.s
+++ lld/trunk/test/ELF/sectionstart-noallochdr.s
@@ -0,0 +1,23 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: ld.lld %t.o --section-start .data=0x20 \
+# RUN: --section-start .bss=0x30 --section-start .text=0x10 -o %t1
+# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
+
+# CHECK:      Sections:
+# CHECK-NEXT:  Idx Name          Size      Address          Type
+# CHECK-NEXT:    0               00000000 0000000000000000
+# CHECK-NEXT:    1 .text         00000001 0000000000000010 TEXT DATA
+# CHECK-NEXT:    2 .data         00000004 0000000000000020 DATA
+# CHECK-NEXT:    3 .bss          00000004 0000000000000030 BSS
+
+.text
+.globl _start
+_start:
+ nop
+
+.data
+.long 0
+
+.bss
+.zero 4


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D32749.97571.patch
Type: text/x-patch
Size: 3187 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170503/03b8f66b/attachment.bin>