[PATCH] D114166: [ELF] Expand LMA region if output section alignment introduces padding

[Konstantin Schwarz via Phabricator via llvm-commits]

kschwarz updated this revision to Diff 388435.
kschwarz marked 5 inline comments as done.
kschwarz edited the summary of this revision.
kschwarz added a comment.

Address comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D114166/new/

https://reviews.llvm.org/D114166

Files:
  lld/ELF/LinkerScript.cpp
  lld/test/ELF/linkerscript/lma-align2.test


Index: lld/test/ELF/linkerscript/lma-align2.test
===================================================================
--- /dev/null
+++ lld/test/ELF/linkerscript/lma-align2.test
@@ -0,0 +1,35 @@
+# REQUIRES: x86
+# RUN: echo '.globl _start; _start: ret;' | \
+# RUN:   llvm-mc -filetype=obj -triple=x86_64 - -o %t.o
+# RUN: ld.lld -T %s %t.o -o %t
+# RUN: llvm-readelf -S -l %t | FileCheck %s
+
+# CHECK:      Name         Type     Address          Off    Size   ES Flg Lk Inf Al
+# CHECK-NEXT:              NULL     0000000000000000 000000 000000 00      0   0  0
+# CHECK-NEXT: .text        PROGBITS 0000000008000000 001000 000001 00  AX  0   0  4
+# CHECK-NEXT: .data        PROGBITS 0000000020000000 002000 000006 00  AX  0   0  8
+# CHECK-NEXT: .data2       PROGBITS 000000000800000e 00200e 000008 00  AX  0   0  1
+# CHECK-NEXT: .data3       PROGBITS 0000000020000008 002018 000000 00  AX  0   0  8
+# CHECK-NEXT: .data4       PROGBITS 0000000008000018 002018 000008 00  AX  0   0  1
+
+
+# CHECK:      Type  Offset   VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
+# CHECK-NEXT: LOAD  0x001000 0x0000000008000000 0x0000000008000000 0x000001 0x000001 R E 0x1000
+# CHECK-NEXT: LOAD  0x002000 0x0000000020000000 0x0000000008000008 0x000006 0x000006 R E 0x1000
+# CHECK-NEXT: LOAD  0x00200e 0x000000000800000e 0x000000000800000e 0x000008 0x000008 R E 0x1000
+# CHECK-NEXT: LOAD  0x002018 0x0000000008000018 0x0000000008000018 0x000008 0x000008 R E 0x1000
+
+MEMORY {
+  CODE (rx) : ORIGIN = 0x08000000, LENGTH = 100K
+  DATA (rw) : ORIGIN = 0x20000000, LENGTH = 100K
+}
+
+SECTIONS {
+  .text : { *(.text) } > CODE
+  ## Aligning the start address of .data to 8 should also increase the location counter of CODE.
+  .data : ALIGN(8) { . += 6; } > DATA AT> CODE
+  .data2 : { . += 8; } > CODE
+  ## Also an empty output section with an alignment requirement increases the location counter.
+  .data3 : ALIGN(8) { . = ALIGN(. != 0 ? 4 : 1); } > DATA AT> CODE
+  .data4 : { . += 8; } > CODE
+}
Index: lld/ELF/LinkerScript.cpp
===================================================================
--- lld/ELF/LinkerScript.cpp
+++ lld/ELF/LinkerScript.cpp
@@ -976,12 +976,16 @@
   // reuse previous lmaOffset; otherwise, reset lmaOffset to 0. This emulates
   // heuristics described in
   // https://sourceware.org/binutils/docs/ld/Output-Section-LMA.html
-  if (sec->lmaExpr)
+  if (sec->lmaExpr) {
     ctx->lmaOffset = sec->lmaExpr().getValue() - dot;
-  else if (MemoryRegion *mr = sec->lmaRegion)
-    ctx->lmaOffset = alignTo(mr->curPos, sec->alignment) - dot;
-  else if (!sameMemRegion || !prevLMARegionIsDefault)
+  } else if (MemoryRegion *mr = sec->lmaRegion) {
+    uint64_t lmaStart = alignTo(mr->curPos, sec->alignment);
+    if (mr->curPos < lmaStart)
+      expandMemoryRegion(mr, lmaStart - mr->curPos, mr->name, sec->name);
+    ctx->lmaOffset = lmaStart - dot;
+  } else if (!sameMemRegion || !prevLMARegionIsDefault) {
     ctx->lmaOffset = 0;
+  }
 
   // Propagate ctx->lmaOffset to the first "non-header" section.
   if (PhdrEntry *l = ctx->outSec->ptLoad)


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