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[lld][ELF][test] Expand testing of symbols in mergeable sections 

Whilst reviewing some internal testing, I noticed a couple of holes in
coverage of mergeable sections containing symbols. This patch addresses
these holes:
1) Show that mid-piece symbols have their values updated properly when
   pieces are merged.
2) Show the behaviour of symbols in mergeable pieces when --gc-sections
   is enabled.

Reviewed by: grimar, MaskRay

Differential Revision: https://reviews.llvm.org/D86543
This commit is contained in:
James Henderson 2020-08-25 15:54:34 +01:00
parent 5ba4d0365b
commit d2385f6d2f
2 changed files with 47 additions and 10 deletions
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37
lld/test/ELF/merge-sym-gc.s Normal file
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# REQUIRES: x86
## Show how symbols in GCed mergeable pieces behave.
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
# RUN: ld.lld --gc-sections %t.o -o %t.elf
# RUN: llvm-readelf %t.elf --sections --syms | FileCheck %s
.section .rodata.merge,"aM",@progbits,4
a1: ## Unreferenced. In first fragment, kept by a2 reference.
.short 1
a2: ## Referenced.
.short 1
b1: ## Unreferenced. Discarded as second fragment is unreferenced.
.short 1
b2: ## Unreferenced. Discarded as second fragment is unreferenced.
.short 1
c1: ## Referenced.
.short 1
c2: ## Unreferenced. In third fragment, kept by c1 reference.
.short 1
.data
.global _start
_start:
.quad a2
.quad c1
# CHECK: .rodata PROGBITS [[#%x, ADDR:]]
# CHECK: Symbol table '.symtab' contains 6 entries:
# CHECK-NEXT: Num: Value {{.*}} Ndx Name
# CHECK-NEXT: 0: {{.*}} UND{{ *$}}
# CHECK-NEXT: 1: {{0*}}[[#ADDR]] {{.*}} a1
# CHECK-NEXT: 2: {{0*}}[[#ADDR+2]] {{.*}} a2
# CHECK-NEXT: 3: {{0*}}[[#ADDR]] {{.*}} c1
# CHECK-NEXT: 4: {{0*}}[[#ADDR+2]] {{.*}} c2
# CHECK-NEXT: 5: {{.*}} _start

20
lld/test/ELF/merge-sym.s
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// REQUIRES: x86
// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
// RUN: ld.lld %t.o -o %t.so -shared
// RUN: llvm-readobj --symbols -S %t.so | FileCheck %s
// RUN: llvm-readelf --symbols -S %t.so | FileCheck %s
.section .rodata.cst4,"aM",@progbits,4
.short 0
foo:
.short 42
.short 0
bar:
.short 42
// CHECK: Name: .rodata
// CHECK-NEXT: Type: SHT_PROGBITS
// CHECK-NEXT: Flags [
// CHECK-NEXT: SHF_ALLOC
// CHECK-NEXT: SHF_MERGE
// CHECK-NEXT: ]
// CHECK-NEXT: Address: 0x20D
// CHECK: Name Type Address {{.*}} ES Flg
// CHECK: .rodata PROGBITS [[#%x, ADDR:]] {{.*}} 04 AM{{ }}
// CHECK: Name: foo
// CHECK-NEXT: Value: 0x20F
// CHECK: Symbol table '.symtab' contains {{.*}} entries:
// CHECK-NEXT: Num: Value {{.*}} Name
// CHECK-DAG: {{.*}}: {{0*}}[[#ADDR+2]] {{.*}} foo
// CHECK-DAG: {{.*}}: {{0*}}[[#ADDR+2]] {{.*}} bar