Completely rewrite ELFObjectWriter::RecordRelocation.

I started trying to fix a small issue, but this code has seen a small fix too
many.

The old code was fairly convoluted. Some of the issues it had:

* It failed to check if a symbol difference was in the some section when
  converting a relocation to pcrel.
* It failed to check if the relocation was already pcrel.
* The pcrel value computation was wrong in some cases (relocation-pc.s)
* It was missing quiet a few cases where it should not convert symbol
  relocations to section relocations, leaving the backends to patch it up.
* It would not propagate the fact that it had changed a relocation to pcrel,
  requiring a quiet nasty work around in ARM.
* It was missing comments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205076 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 30 insertions, 9 deletions

diff --git a/test/MC/ELF/bad-expr2.s b/test/MC/ELF/bad-expr2.s
new file mode 100644
index 0000000000..3da916b7fa
--- /dev/null
+++ b/test/MC/ELF/bad-expr2.s
@@ -0,0 +1,12 @@
+// RUN: not llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o /dev/null \
+// RUN: 2>&1 | FileCheck %s
+
+// CHECK: No relocation available to represent this relative expression
+// CHECK: call foo - bar
+
+
+        call foo - bar
+        .section .foo
+foo:
+        .section .bar
+bar:
diff --git a/test/MC/ELF/bad-expr3.s b/test/MC/ELF/bad-expr3.s
new file mode 100644
index 0000000000..990167cda5
--- /dev/null
+++ b/test/MC/ELF/bad-expr3.s
@@ -0,0 +1,10 @@
+// RUN: not llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o /dev/null \
+// RUN: 2>&1 | FileCheck %s
+
+// CHECK: Cannot represent a difference across sections
+
+        .long foo - bar
+        .section .zed
+foo:
+        .section .bah
+bar:
diff --git a/test/MC/ELF/merge.s b/test/MC/ELF/merge.s
index 0e92583192..d6e0b7c4b7 100644
--- a/test/MC/ELF/merge.s
+++ b/test/MC/ELF/merge.s
@@ -1,10 +1,7 @@
 // RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -r | FileCheck  %s
 
-// Test that PIC relocations with local symbols in a mergeable section are done
-// with a reference to the symbol. Not sure if this is a linker limitation,
-// but this matches the behavior of gas.
-
-// Non-PIC relocations with 0 offset don't use the symbol.
+// Test that relocations with local symbols in a mergeable section are done
+// with a reference to the symbol if the offset is non zero.
 
 
         movsd   .Lfoo(%rip), %xmm1
@@ -13,6 +10,7 @@
         jmp	foo@PLT
         movq 	foo@GOTPCREL, %rax
         movq    zed, %rax
+        movsd   .Lfoo+4(%rip), %xmm1
 
         .section        .sec1,"aM",@progbits,16
 .Lfoo:
@@ -30,5 +28,6 @@ foo:
 // CHECK-NEXT:     0x{{[^ ]+}} R_X86_64_PLT32    foo  0x{{[^ ]+}}
 // CHECK-NEXT:     0x{{[^ ]+}} R_X86_64_GOTPCREL foo  0x{{[^ ]+}}
 // CHECK-NEXT:     0x{{[^ ]+}} R_X86_64_32S      zed  0x{{[^ ]+}}
+// CHECK-NEXT:     0x{{[^ ]+}} R_X86_64_PC32    .sec1 0x{{[^ ]+}}
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
diff --git a/test/MC/ELF/relocation-386.s b/test/MC/ELF/relocation-386.s
index e8c31fc85c..1409465b73 100644
--- a/test/MC/ELF/relocation-386.s
+++ b/test/MC/ELF/relocation-386.s
@@ -5,7 +5,7 @@
 
 // CHECK:      Relocations [
 // CHECK-NEXT:   Section (2) .rel.text {
-// CHECK-NEXT:     0x2          R_386_GOTOFF     .Lfoo 0x0
+// CHECK-NEXT:     0x2          R_386_GOTOFF     .rodata.str1.16 0x0
 // CHECK-NEXT:     0x{{[^ ]+}}  R_386_PLT32      bar2 0x0
 // CHECK-NEXT:     0x{{[^ ]+}}  R_386_GOTPC      _GLOBAL_OFFSET_TABLE_ 0x0
 // Relocation 3 (bar3@GOTOFF) is done with symbol 7 (bss)
@@ -67,7 +67,7 @@
 
 // Symbol 4 is zed
 // CHECK:        Symbol {
-// CHECK:          Name: zed (53)
+// CHECK:          Name: zed
 // CHECK-NEXT:     Value: 0x0
 // CHECK-NEXT:     Size: 0
 // CHECK-NEXT:     Binding: Local
diff --git a/test/MC/ELF/relocation-pc.s b/test/MC/ELF/relocation-pc.s
index fc7420c398..0ce32010cf 100644
--- a/test/MC/ELF/relocation-pc.s
+++ b/test/MC/ELF/relocation-pc.s
@@ -26,7 +26,7 @@
 // CHECK-NEXT:     AddressAlignment: 8
 // CHECK-NEXT:     EntrySize: 24
 // CHECK-NEXT:     Relocations [
-// CHECK-NEXT:       0x1 R_X86_64_PC8 - 0x0
-// CHECK-NEXT:       0x3 R_X86_64_PC32 - 0x0
+// CHECK-NEXT:       0x1 R_X86_64_PC8 - 0xFFFFFFFFFFFFFFFF
+// CHECK-NEXT:       0x3 R_X86_64_PC32 - 0xFFFFFFFFFFFFFEFC
 // CHECK-NEXT:     ]
 // CHECK-NEXT:   }