[ELF] Restore arm-branch.s test

[ikudrin]

Summary

After D77330, the comments are inconsistent with the disassembled code. As the value of far has been changed, a thunk to reach it is now generated, and target addresses of branch instructions are different from what was initially expected.

The patch fixes that and makes the test closer to what it was originally.

[peter.smith]

LGTM. We could probably improve the test further with some stable addresses in the linker script, and a max range backwards branch. However that's probably overdoing it for this test as we've gots lots of others that will cover that.

[MaskRay]

LGTM.

lld/test/ELF/Inputs/far-long-arm-abs.s

10

Add a newline

lld/test/ELF/arm-branch.s

8–9

add a file-level comment what this test does. it is not obvious.

[ikudrin]

lld/test/ELF/arm-branch.s

8–9

Well, as I am not the author of the test, I cannot tell for sure the initial intentions; I merely restored its original functionality and fixed comments. Do you have any suggestions about the description? @peter.smith, maybe you, as the first committer, could help with that?

[peter.smith]

I've made a suggestion for a comment.

lld/test/ELF/arm-branch.s

8–9

I think this was one of the first patches I wrote which introduced just enough Arm support to link hello world. As an introductory comment how about.

/// Test the Arm state R_ARM_CALL and R_ARM_JUMP24 relocation to Arm state destinations.
/// R_ARM_CALL is used for branch and link (BL)
/// R_ARM_JUMP24 is used for unconditional and conditional branches (B and B<cc>)
/// Relocations defined in https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst
/// Addend A is always -8 to cancel out Arm state PC-bias of 8 bytes

[ikudrin]

• Added a missing newline in far-long-arm-abs.s
• Added a description for arm-branch.s

lld/test/ELF/arm-branch.s

8–9

Thank you for the description!

lld/test/ELF/Inputs/far-arm-abs.s

-.global far
-.type far,%function
-far = 0x202001c
-
 .global too_far1
 .type too_far1,%function
 too_far1 = 0x2030008
 .global too_far2
 .type too_far2,%function
 too_far2 = 0x203000c
 .global too_far3
 .type too_far3,%function
 too_far3 = 0x2030010

lld/test/ELF/Inputs/far-long-arm-abs.s

-.global far
-.type far,%function
-far = 0x202001c
-
 .global too_far1
 .type too_far1,%function
 too_far1 = 0x2030014
 .global too_far2
 .type too_far2,%function
 too_far2 = 0x2030020
 .global too_far3
 .type too_far3,%function
-too_far3 = 0x203002c
+too_far3 = 0x203002c
 

lld/test/ELF/arm-branch.s

+/// Test the Arm state R_ARM_CALL and R_ARM_JUMP24 relocation to Arm state destinations.
+/// R_ARM_CALL is used for branch and link (BL)
+/// R_ARM_JUMP24 is used for unconditional and conditional branches (B and B<cc>)
+/// Relocations defined in https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst
+/// Addend A is always -8 to cancel out Arm state PC-bias of 8 bytes
+
 // REQUIRES: arm
 // RUN: llvm-mc -filetype=obj -triple=armv7a-none-linux-gnueabi %s -o %t
-// RUN: llvm-mc -filetype=obj -triple=armv7a-none-linux-gnueabi %S/Inputs/far-arm-abs.s -o %tfar
 // RUN: echo "SECTIONS { \
 // RUN:          . = 0xb4; \
 // RUN:          .callee1 : { *(.callee_low) } \
 // RUN:          .caller : { *(.text) } \
 // RUN:          .callee2 : { *(.callee_high) } } " > %t.script
-// RUN: ld.lld --script %t.script %t %tfar -o %t2
+// RUN: ld.lld --defsym=far=0x201001c --script %t.script %t -o %t2
 // RUN: llvm-objdump -d --no-show-raw-insn --triple=armv7a-none-linux-gnueabi %t2 | FileCheck  %s
+
  .syntax unified
  .section .callee_low, "ax",%progbits
  .align 2
  .type callee_low,%function
 callee_low:
  bx lr
 
  .section .text, "ax",%progbits

 
  .section .callee_high, "ax",%progbits
  .align 2
  .type callee_high,%function
 callee_high:
  bx lr
 
 // CHECK: 00010000 <_start>:
-/// S(callee_low) = 0xb4 P = 0x10000 A = -8 = -0xff54 = -65364
+/// S(callee_low) = 0xb4; P = 0x10000; A = -8; S + A - P = -0xff54 = -65364
 // CHECK-NEXT:   10000:       bl      #-65364 <callee_low>
-/// S(callee_low) = 0xb4 P = 0x10004 A = -8 = -0xff58 = -65368
+/// S(callee_low) = 0xb4; P = 0x10004; A = -8; S + A - P = -0xff58 = -65368
 // CHECK-NEXT:   10004:       b       #-65368 <callee_low>
-/// S(callee_low) = 0xb4 P = 0x10008 A = -8 = -0xff5c -65372
+/// S(callee_low) = 0xb4; P = 0x10008; A = -8; S + A - P = -0xff5c = -65372
 // CHECK-NEXT:   10008:       beq     #-65372 <callee_low>
-/// S(callee_high) = 0x10028 P = 0x1000c A = -8 = 0x14 = 20
-// CHECK-NEXT:   1000c:       bl      #28 <callee_high>
-/// S(callee_high) = 0x10028 P = 0x10010 A = -8 = 0x10 = 16
-// CHECK-NEXT:   10010:       b       #24 <callee_high>
-/// S(callee_high) = 0x10028 P = 0x10014 A = -8 = 0x0c =12
-// CHECK-NEXT:   10014:       bne     #20 <callee_high>
-/// S(far) = 0x201001c P = 0x10018 A = -8 = 0x1fffffc = 33554428
-// CHECK-NEXT:   10018:       bl      #8
-/// S(far) = 0x201001c P = 0x1001c A = -8 = 0x1fffff8 = 33554424
-// CHECK-NEXT:   1001c:       b       #4
-/// S(far) = 0x201001c P = 0x10020 A = -8 = 0x1fffff4 = 33554420
-// CHECK-NEXT:   10020:       bgt     #0
+/// S(callee_high) = 0x10028; P = 0x1000c; A = -8; S + A - P = 0x14 = 20
+// CHECK-NEXT:   1000c:       bl      #20 <callee_high>
+/// S(callee_high) = 0x10028; P = 0x10010; A = -8; S + A - P = 0x10 = 16
+// CHECK-NEXT:   10010:       b       #16 <callee_high>
+/// S(callee_high) = 0x10028; P = 0x10014; A = -8; S + A - P = 0x0c = 12
+// CHECK-NEXT:   10014:       bne     #12 <callee_high>
+/// S(far) = 0x201001c; P = 0x10018; A = -8; S + A - P = 0x1fffffc = 33554428
+// CHECK-NEXT:   10018:       bl      #33554428
+/// S(far) = 0x201001c; P = 0x1001c; A = -8; S + A - P = 0x1fffff8 = 33554424
+// CHECK-NEXT:   1001c:       b       #33554424
+/// S(far) = 0x201001c; P = 0x10020; A = -8; S + A - P = 0x1fffff4 = 33554420
+// CHECK-NEXT:   10020:       bgt     #33554420
 // CHECK-NEXT:   10024:       bx      lr