[LLD] [TEST] Add test case for patching an absolute relocation to a weak undef

[bd1976llvm]

Summary

I noticed that we had this case in our internal testsuite but couldn't find it in LLD's tests.

This adds that case.

[peter.smith]

Looks good to me, worth waiting to see if MaskRay has any comments first.

[MaskRay]

Consider adding --hex-dump test to weak-undef.s or weak-undef-rw.s

[bd1976llvm]

Additionally augmented weak-undef.s and weak-undef-rw.s with a --hex-dump test.

[MaskRay]

Sorry for the slow response. I was out of town for one week.

It'd be better reorganize the tests further as their filenames are quite confusing now.

[bd1976llvm]

Do not test reloc offset as its value isn't important.

[bd1976llvm]

In D110716#3047094, @MaskRay wrote:

Sorry for the slow response. I was out of town for one week.

Thanks. I made one minor change after your review as I realised that I didn't need to check the value of the relocation offset in lld/test/ELF/weak-undef.s.

It'd be better reorganize the tests further as their filenames are quite confusing now.

Agreed. It might help readers to amalgamate all of these weak undef cases into a single test file.

lld/test/ELF/relocation-undefined-weak.s

 # REQUIRES: x86
 
 ## On some targets (e.g. ARM, AArch64, and PPC), PC relative relocations to
 ## weak undefined symbols resolve to special positions. On many others
-## the target symbols as treated as VA 0.
+## the target symbols as treated as VA 0. Absolute relocations are always 
+## resolved as VA 0.
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
 # RUN: ld.lld %t.o -o %t
-# RUN: llvm-objdump -d --no-show-raw-insn --print-imm-hex %t | FileCheck %s
+
+# RUN: llvm-objdump -d --no-show-raw-insn --print-imm-hex %t | FileCheck %s --check-prefix=TEXT
+# TEXT: 201158: movl $0x1, -0x201162(%rip)
+
+# RUN: llvm-readelf -r --hex-dump=.data %t | FileCheck %s --check-prefix=DATA
+# DATA: Hex dump of section '.data':
+# DATA-NEXT: {{.*}} 00000000 00000000 
+# DATA-EMPTY:
+
+# RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=NORELCS
+# NORELCS: no relocations
 
 .global _start
 _start:
   movl $1, sym1(%rip)
 
+.data
 .weak sym1
-
-# CHECK: 201120: movl $0x1, -0x20112a(%rip)
+.quad sym1

lld/test/ELF/weak-undef-rw.s

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
 # RUN: ld.lld %t.o -o %t --export-dynamic
-# RUN: llvm-readelf -r %t | FileCheck %s --check-prefix=NOPIC
+# RUN: llvm-readelf -r --hex-dump=.data %t | FileCheck %s --check-prefix=NOPIC
 # RUN: ld.lld %t.o -o %t.pie -pie
 # RUN: llvm-readobj -r %t.pie | FileCheck %s --check-prefix=PIC
 # RUN: ld.lld %t.o -o %t.so -shared
 # RUN: llvm-readobj -r %t.so | FileCheck %s --check-prefix=PIC
 
 ## gABI leaves the behavior of weak undefined references implementation defined.
 ## We choose to resolve them statically for -no-pie and produce dynamic relocations
 ## for -pie and -shared.
 ##
 ## Note: Some ports of GNU ld support -z nodynamic-undefined-weak that we don't
 ## implement.
 
 # NOPIC: no relocations
+# NOPIC: Hex dump of section '.data':
+# NOPIC-NEXT: {{.*}} 00000000 00000000 
+# NOPIC-EMPTY:
 
 # PIC:      .rela.dyn {
 # PIC-NEXT:   R_X86_64_64 foobar 0x0
 # PIC-NEXT: }
 
         .global _start
 _start:
         .data
         .weak foobar
         .quad foobar

lld/test/ELF/weak-undef.s

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
 # RUN: ld.lld %t.o -o %t --export-dynamic
-# RUN: llvm-readobj --dyn-syms %t | FileCheck %s
+# RUN: llvm-readelf -r --dyn-syms --hex-dump=.data %t | \
+# RUN:   FileCheck %s --check-prefixes=NORELOC,COMMON
+
+# NORELOC: There are no relocations in this file.
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %p/Inputs/dummy-shared.s -o %t1.o
 # RUN: ld.lld %t1.o -shared -o %t1.so
 # RUN: ld.lld %t.o -o %t %t1.so -pie
-# RUN: llvm-readobj --dyn-syms %t | FileCheck %s
+# RUN: llvm-readelf -r --dyn-syms --hex-dump=.data %t | \
+# RUN:   FileCheck %s --check-prefixes=RELOC,COMMON
+
+# RELOC:      Relocation section '.rela.dyn' at offset {{.*}} contains 1 entries:
+# RELOC-NEXT: Offset Info Type Symbol's Value Symbol's Name + Addend
+# RELOC-NEXT: {{.*}} 0000000100000001 R_X86_64_64 0000000000000000 foo + 0
 
-# CHECK:      DynamicSymbols [
-# CHECK-NEXT:   Symbol {
-# CHECK-NEXT:     Name:
-# CHECK-NEXT:     Value: 0x0
-# CHECK-NEXT:     Size: 0
-# CHECK-NEXT:     Binding: Local (0x0)
-# CHECK-NEXT:     Type: None (0x0)
-# CHECK-NEXT:     Other: 0
-# CHECK-NEXT:     Section: Undefined (0x0)
-# CHECK-NEXT:   }
-# CHECK-NEXT:   Symbol {
-# CHECK-NEXT:     Name: foo
-# CHECK-NEXT:     Value: 0x0
-# CHECK-NEXT:     Size: 0
-# CHECK-NEXT:     Binding: Weak
-# CHECK-NEXT:     Type: None
-# CHECK-NEXT:     Other: 0
-# CHECK-NEXT:     Section: Undefined
-# CHECK-NEXT:   }
-# CHECK-NEXT: ]
+# COMMON:       Symbol table '.dynsym' contains 2 entries:
+# COMMON-NEXT:  Num: Value Size Type Bind Vis Ndx Name
+# COMMON-NEXT:  0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
+# COMMON-NEXT:  1: 0000000000000000 0 NOTYPE WEAK DEFAULT UND foo
+# COMMON:      Hex dump of section '.data':
+# COMMON-NEXT: {{.*}} 00000000 00000000 
+# COMMON-EMPTY:
 
 .weak foo
 
 .data
   .dc.a foo