[ELF] - Linkerscript: fixed non-determinism when handling MEMORY.

When findMemoryRegion do search to find a region for output section it
iterates over MemoryRegions which is DenseMap and so does not
guarantee iteration in insertion order. As a result selected region depends
on its name and not on its definition position
Testcase shows the issue, patch fixes it. Behavior after applying the patch
seems consistent with bfd.

Differential revision: https://reviews.llvm.org/D39544

llvm-svn: 317307

diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
index 478405d..ba9e877 100644 (file)
--- a/lld/ELF/LinkerScript.h
+++ b/lld/ELF/LinkerScript.h
@@ -277,7 +277,7 @@ public:
   std::vector<InputSectionDescription *> KeptSections;
 
   // A map from memory region name to a memory region descriptor.
-  llvm::DenseMap<llvm::StringRef, MemoryRegion *> MemoryRegions;
+  llvm::MapVector<llvm::StringRef, MemoryRegion *> MemoryRegions;
 
   // A list of symbols referenced by the script.
   std::vector<llvm::StringRef> ReferencedSymbols;

diff --git a/lld/ELF/ScriptParser.cpp b/lld/ELF/ScriptParser.cpp
index 7ec6122..af9bf19 100644 (file)
--- a/lld/ELF/ScriptParser.cpp
+++ b/lld/ELF/ScriptParser.cpp
@@ -422,7 +422,7 @@ void ScriptParser::readRegionAlias() {
     setError("redefinition of memory region '" + Alias + "'");
   if (!Script->MemoryRegions.count(Name))
     setError("memory region '" + Name + "' is not defined");
-  Script->MemoryRegions[Alias] = Script->MemoryRegions[Name];
+  Script->MemoryRegions.insert({Alias, Script->MemoryRegions[Name]});
 }
 
 void ScriptParser::readSearchDir() {

diff --git a/lld/test/ELF/linkerscript/memory3.s b/lld/test/ELF/linkerscript/memory3.s
new file mode 100644 (file)
index 0000000..f85d089
--- /dev/null
+++ b/lld/test/ELF/linkerscript/memory3.s
@@ -0,0 +1,23 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "MEMORY { ram2 (ax) : ORIGIN = 0x1000, LENGTH = 1K   \
+# RUN:                ram1 (ax) : ORIGIN = 0x4000, LENGTH = 1K } \
+# RUN: SECTIONS {}" > %t1.script
+# RUN: ld.lld -o %t1 --script %t1.script %t
+# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
+
+# RUN: echo "MEMORY { ram1 (ax) : ORIGIN = 0x1000, LENGTH = 1K   \
+# RUN:                ram2 (ax) : ORIGIN = 0x4000, LENGTH = 1K } \
+# RUN: SECTIONS {}" > %t2.script
+# RUN: ld.lld -o %t2 --script %t2.script %t
+# RUN: llvm-objdump -section-headers %t2 | FileCheck %s
+
+## Check we place .text into first defined memory region with appropriate flags.
+# CHECK: Sections:
+# CHECK: Idx Name  Size      Address
+# CHECK:   0       00000000 0000000000000000
+# CHECK:   1 .text 00000001 0000000000001000
+  
+.section .text.foo,"ax",%progbits
+foo:
+  nop