[LLD] Only increase LMARegion if different from MemRegion

Patch by Konstantin Schwarz!

If both the MemRegion and LMARegion are set for an output section in
a linker script, we should only increase the LMARegion if it is
different from the MemRegion. Otherwise, we reserve the memory twice.

Differential revision: https://reviews.llvm.org/D50065

llvm-svn: 338684

lld/ELF/LinkerScript.cpp

@@ -116,7 +116,8 @@ void LinkerScript::expandMemoryRegions(uint64_t Size) {
   if (Ctx->MemRegion)
     expandMemoryRegion(Ctx->MemRegion, Size, Ctx->MemRegion->Name,
                        Ctx->OutSec->Name);
-  if (Ctx->LMARegion)
+  // Only expand the LMARegion if it is different from MemRegion.
+  if (Ctx->LMARegion && Ctx->MemRegion != Ctx->LMARegion)
     expandMemoryRegion(Ctx->LMARegion, Size, Ctx->LMARegion->Name,
                        Ctx->OutSec->Name);
 }

lld/test/ELF/linkerscript/Inputs/at7.s

@@ -0,0 +1,7 @@
+.global _start
+.text
+_start:
+nop
+
+.section .sec, "aw"
+.word 4

lld/test/ELF/linkerscript/at7.test

@@ -0,0 +1,28 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/at7.s -o %t.o
+# RUN: ld.lld %t.o --script %s -o %t
+# RUN: llvm-readelf -sections -program-headers %t | FileCheck %s
+
+MEMORY {
+  RAM    : ORIGIN = 0x20000000, LENGTH = 0x200
+}
+
+SECTIONS {
+ .text : { *(.text) } > RAM AT> RAM
+ .sec  : { *(.sec)  } > RAM
+}
+
+# Make sure the memory for the .text section is only reserved once.
+# Previously, the location counter for both MemRegion and LMARegion
+# was increased unconditionally.
+
+
+# CHECK: Name              Type            Address          Off
+# CHECK: .text             PROGBITS        0000000020000000 001000
+# CHECK: .sec             PROGBITS        0000000020000001 001001
+
+# CHECK: Program Headers:
+# CHECK:      Type  Offset   VirtAddr           PhysAddr
+# CHECK-NEXT: LOAD  0x001000 0x0000000020000000 0x0000000020000000
+# CHECK-NEXT: LOAD  0x001001 0x0000000020000001 0x0000000020000001
+# CHECK-NOT: LOAD