[lld] r256392 - Update the recorded CIE length when aligning.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Thu Dec 24 14:44:06 2015
New Revision: 256392

URL: http://llvm.org/viewvc/llvm-project?rev=256392&view=rev
Log:
Update the recorded CIE length when aligning.

We cannot just pad with 0s as that would be a terminator mark.

Added:
    lld/trunk/test/ELF/eh-align-cie.s
Modified:
    lld/trunk/ELF/OutputSections.cpp

Modified: lld/trunk/ELF/OutputSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=256392&r1=256391&r2=256392&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.cpp (original)
+++ lld/trunk/ELF/OutputSections.cpp Thu Dec 24 14:44:06 2015
@@ -1038,23 +1038,30 @@ void EHOutputSection<ELFT>::addSection(E
   return addSectionAux(S, Obj.rels(RelSec));
 }
 
+template <class ELFT>
+static typename ELFFile<ELFT>::uintX_t writeAlignedCieOrFde(StringRef Data,
+                                                            uint8_t *Buf) {
+  typedef typename ELFFile<ELFT>::uintX_t uintX_t;
+  const endianness E = ELFT::TargetEndianness;
+  uint64_t Len = RoundUpToAlignment(Data.size(), sizeof(uintX_t));
+  write32<E>(Buf, Len - 4);
+  memcpy(Buf + 4, Data.data() + 4, Data.size() - 4);
+  return Len;
+}
+
 template <class ELFT> void EHOutputSection<ELFT>::writeTo(uint8_t *Buf) {
   const endianness E = ELFT::TargetEndianness;
   size_t Offset = 0;
   for (const Cie<ELFT> &C : Cies) {
     size_t CieOffset = Offset;
 
-    StringRef CieData = C.data();
-    memcpy(Buf + Offset, CieData.data(), CieData.size());
+    uintX_t CIELen = writeAlignedCieOrFde<ELFT>(C.data(), Buf + Offset);
     C.S->Offsets[C.Index].second = Offset;
-    Offset += RoundUpToAlignment(CieData.size(), sizeof(uintX_t));
+    Offset += CIELen;
 
     for (const EHRegion<ELFT> &F : C.Fdes) {
-      StringRef FdeData = F.data();
-      uintX_t Len = RoundUpToAlignment(FdeData.size(), sizeof(uintX_t));
-      write32<E>(Buf + Offset, Len - 4);                    // Length
+      uintX_t Len = writeAlignedCieOrFde<ELFT>(F.data(), Buf + Offset);
       write32<E>(Buf + Offset + 4, Offset + 4 - CieOffset); // Pointer
-      memcpy(Buf + Offset + 8, FdeData.data() + 8, FdeData.size() - 8);
       F.S->Offsets[F.Index].second = Offset;
       Offset += Len;
     }

Added: lld/trunk/test/ELF/eh-align-cie.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/eh-align-cie.s?rev=256392&view=auto
==============================================================================
--- lld/trunk/test/ELF/eh-align-cie.s (added)
+++ lld/trunk/test/ELF/eh-align-cie.s Thu Dec 24 14:44:06 2015
@@ -0,0 +1,57 @@
+// REQUIRES: x86
+
+	.cfi_startproc
+	.cfi_personality 0x1b, bar
+	.cfi_endproc
+
+.global bar
+.hidden bar
+bar:
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: llvm-readobj -s -section-data %t.o | FileCheck --check-prefix=OBJ %s
+
+// Check the size of the CIE (0x18 + 4) an FDE (0x10 + 4)
+// OBJ: Name: .eh_frame
+// OBJ-NEXT:    Type:
+// OBJ-NEXT:    Flags [
+// OBJ-NEXT:      SHF_ALLOC
+// OBJ-NEXT:    ]
+// OBJ-NEXT:    Address:
+// OBJ-NEXT:    Offset:
+// OBJ-NEXT:    Size:
+// OBJ-NEXT:    Link:
+// OBJ-NEXT:    Info:
+// OBJ-NEXT:    AddressAlignment:
+// OBJ-NEXT:    EntrySize:
+// OBJ-NEXT:    SectionData (
+// OBJ-NEXT:      0000: 18000000 00000000 017A5052 00017810
+// OBJ-NEXT:      0010: 061B0000 00001B0C 07089001 10000000
+// OBJ-NEXT:      0020: 20000000 00000000 00000000 00000000
+// OBJ-NEXT:    )
+
+
+// RUN: ld.lld %t.o -o %t -shared
+// RUN: llvm-readobj -s -section-data %t | FileCheck %s
+
+// Check that the size of the CIE was changed to (0x1C + 4) and the FDE one was
+// changed to (0x14 + 4)
+
+// CHECK:      Name: .eh_frame
+// CHECK-NEXT: Type:
+// CHECK-NEXT: Flags
+// CHECK-NEXT:   SHF_ALLOC
+// CHECK-NEXT: ]
+// CHECK-NEXT: Address:
+// CHECK-NEXT: Offset:
+// CHECK-NEXT: Size:
+// CHECK-NEXT: Link:
+// CHECK-NEXT: Info:
+// CHECK-NEXT: AddressAlignment:
+// CHECK-NEXT: EntrySize:
+// CHECK-NEXT: SectionData (
+// CHECK-NEXT:   0000: 1C000000 00000000 017A5052 00017810
+// CHECK-NEXT:   0010: 061B260E 00001B0C 07089001 00000000
+// CHECK-NEXT:   0020: 14000000 24000000 100E0000 00000000
+// CHECK-NEXT:   0030: 00000000 00000000
+// CHECK-NEXT: )