[lld] [lld] Support thumb PLTs (PR #86223)

[Peter Smith via llvm-commits]

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@@ -0,0 +1,121 @@
+// REQUIRES: arm
+// RUN: llvm-mc -filetype=obj -arm-add-build-attributes --arch=thumb --mcpu=cortex-m33 %p/Inputs/arm-plt-reloc.s -o %t1
+// RUN: llvm-mc -filetype=obj -arm-add-build-attributes --arch=thumb --mcpu=cortex-m33 %s -o %t2
+// RUN: ld.lld %t1 %t2 -o %t
+// RUN: llvm-objdump --no-print-imm-hex -d %t | FileCheck %s
+// RUN: ld.lld -shared %t1 %t2 -o %t.so
+// RUN: llvm-objdump --no-print-imm-hex -d %t.so | FileCheck --check-prefix=DSO %s
+// RUN: llvm-readobj -S -r %t.so | FileCheck -check-prefix=DSOREL %s
+
+// RUN: llvm-mc -filetype=obj -arm-add-build-attributes --arch=thumbeb --mcpu=cortex-m33 %p/Inputs/arm-plt-reloc.s -o %t1.be
+// RUN: llvm-mc -filetype=obj -arm-add-build-attributes --arch=thumbeb --mcpu=cortex-m33 %s -o %t2.be
+// RUN: ld.lld %t1.be %t2.be -o %t.be
+// RUN: llvm-objdump --no-print-imm-hex -d %t.be | FileCheck %s
+// RUN: ld.lld -shared %t1.be %t2.be -o %t.so.be
+// RUN: llvm-objdump --no-print-imm-hex -d %t.so.be | FileCheck --check-prefix=DSO %s
+// RUN: llvm-readobj -S -r %t.so.be | FileCheck -check-prefix=DSOREL %s
+
+// RUN: ld.lld --be8 %t1.be %t2.be -o %t.be
+// RUN: llvm-objdump --no-print-imm-hex -d %t.be | FileCheck %s
+// RUN: ld.lld --be8 -shared %t1.be %t2.be -o %t.so.be
+// RUN: llvm-objdump --no-print-imm-hex -d %t.so.be | FileCheck --check-prefix=DSO %s
+// RUN: llvm-readobj -S -r %t.so.be | FileCheck -check-prefix=DSOREL %s
+
+// Test PLT entry generation
+ .text
+ .align 2
+ .globl _start
+ .type  _start,%function
+_start:
+// FIXME, interworking is only supported for BL via BLX at the moment, when
+// interworking thunks are available for b.w and b<cond>.w this can be altered
+// to test the different forms of interworking.
+ bl func1
+ bl func2
+ bl func3
+
+// Executable, expect no PLT
+// CHECK: Disassembly of section .text:
+// CHECK-EMPTY:
+// CHECK-NEXT: <func1>:
+// CHECK-NEXT:   200b4: 4770    bx      lr
+// CHECK: <func2>:
+// CHECK-NEXT:   200b6: 4770    bx      lr
+// CHECK: <func3>:
+// CHECK-NEXT:   200b8: 4770    bx      lr
+// CHECK-NEXT:   200ba: d4d4 
+// CHECK: <_start>:
+// CHECK-NEXT:   200bc: f7ff fffa       bl      0x200b4 <func1>
+// CHECK-NEXT:   200c0: f7ff fff9       bl      0x200b6 <func2>
+// CHECK-NEXT:   200c4: f7ff fff8       bl      0x200b8 <func3>
+
+// Expect PLT entries as symbols can be preempted
+// .text is Thumb and .plt is ARM, llvm-objdump can currently only disassemble
----------------
smithp35 wrote:

Don't need this comment anymore as the .plt is Thumb only. I think llvm-objdump is now smart enough to disassemble Arm and Thumb too.

https://github.com/llvm/llvm-project/pull/86223