[ELF] - Do not forget to expand the memory region.

[grimar]

Summary

This is PR36799.

Currently, we might have a bug with scripts like below:

.foo : ALIGN(8) 
{
  *(.foo)
} > ram

because do not expand the memory region when doing ALIGN.
This might result in file range overlaps. The patch fixes the issue.

[grimar]

• Minor change.

[• espindola]

LGTM with nits.

test/ELF/linkerscript/memory-region-alignment.test

12 ↗

(On Diff #139277)

Can you avoid orphan sections?

19 ↗

(On Diff #139277)

Can you use CHECK-NEXT?

lld/trunk/ELF/LinkerScript.h

class LinkerScript final {
   };
 
   llvm::DenseMap<StringRef, OutputSection *> NameToOutputSection;
 
   void addSymbol(SymbolAssignment *Cmd);
   void assignSymbol(SymbolAssignment *Cmd, bool InSec);
   void setDot(Expr E, const Twine &Loc, bool InSec);
   void expandOutputSection(uint64_t Size);
+  void expandMemoryRegions(uint64_t Size);
 
   std::vector<InputSection *>
   computeInputSections(const InputSectionDescription *);
 
   std::vector<InputSection *> createInputSectionList(OutputSection &Cmd);
 
   std::vector<size_t> getPhdrIndices(OutputSection *Sec);
 

lld/trunk/ELF/LinkerScript.cpp

static void expandMemoryRegion(MemoryRegion *MemRegion, uint64_t Size,
                                StringRef RegionName, StringRef SecName) {
   MemRegion->CurPos += Size;
   uint64_t NewSize = MemRegion->CurPos - MemRegion->Origin;
   if (NewSize > MemRegion->Length)
     error("section '" + SecName + "' will not fit in region '" + RegionName +
           "': overflowed by " + Twine(NewSize - MemRegion->Length) + " bytes");
 }
 
-void LinkerScript::expandOutputSection(uint64_t Size) {
-  Ctx->OutSec->Size += Size;
+void LinkerScript::expandMemoryRegions(uint64_t Size) {
   if (Ctx->MemRegion)
     expandMemoryRegion(Ctx->MemRegion, Size, Ctx->MemRegion->Name,
                        Ctx->OutSec->Name);
   if (Ctx->LMARegion)
     expandMemoryRegion(Ctx->LMARegion, Size, Ctx->LMARegion->Name,
                        Ctx->OutSec->Name);
 }
 
+void LinkerScript::expandOutputSection(uint64_t Size) {
+  Ctx->OutSec->Size += Size;
+  expandMemoryRegions(Size);
+}
+
 void LinkerScript::setDot(Expr E, const Twine &Loc, bool InSec) {
   uint64_t Val = E().getValue();
   if (Val < Dot && InSec)
     error(Loc + ": unable to move location counter backward for: " +
           Ctx->OutSec->Name);
 
   // Update to location counter means update to section size.
   if (InSec)
void LinkerScript::output(InputSection *S) {
   // SIZEOF works correctly in the case below:
   // .foo { *(.aaa) a = SIZEOF(.foo); *(.bbb) }
   expandOutputSection(Pos - Before);
 }
 
 void LinkerScript::switchTo(OutputSection *Sec) {
   if (Ctx->OutSec == Sec)
     return;
-
   Ctx->OutSec = Sec;
+
+  uint64_t Before = advance(0, 1);
   Ctx->OutSec->Addr = advance(0, Ctx->OutSec->Alignment);
+  expandMemoryRegions(Ctx->OutSec->Addr - Before);
 }
 
 // This function searches for a memory region to place the given output
 // section in. If found, a pointer to the appropriate memory region is
 // returned. Otherwise, a nullptr is returned.
 MemoryRegion *LinkerScript::findMemoryRegion(OutputSection *Sec) {
   // If a memory region name was specified in the output section command,
   // then try to find that region first.

lld/trunk/test/ELF/linkerscript/memory-region-alignment.test

+# REQUIRES: x86
+# RUN: echo '.section .foo,"a"; .quad 0; .section .zed,"M",@progbits,1; .byte 0' > %t.s
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %t.s -o %t.o
+
+MEMORY {
+  ram (rwx): org = 0x1, len = 96K
+}
+
+SECTIONS {
+  .foo : ALIGN(8) {
+    *(.foo)
+  } > ram
+  
+  .zed : {
+    *(.zed)
+  } > ram
+}
+
+# RUN: ld.lld %t.o -o %t --script %s
+# RUN: llvm-readobj -sections %t | FileCheck %s
+
+# CHECK:        Name: .foo
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x8
+# CHECK-NEXT:   Offset: 0x1008
+# CHECK-NEXT:   Size: 8
+
+# CHECK:        Name: .text
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:     SHF_EXECINSTR
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x10
+# CHECK-NEXT:   Offset: 0x1010
+# CHECK-NEXT:   Size: 0
+
+# CHECK:        Name: .zed
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_MERGE
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x10
+# CHECK-NEXT:   Offset: 0x1010
+# CHECK-NEXT:   Size: 1
+
+# CHECK:        Name: .comment
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_MERGE
+# CHECK-NEXT:     SHF_STRINGS
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x0
+# CHECK-NEXT:   Offset: 0x1011
+# CHECK-NEXT:   Size: 8