[PATCH] D87986: [SYCL]Fix bug: objdump find symbol error on adrp instruction when imm < 0 in arm64

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JuunChen created this revision.
Herald added subscribers: llvm-commits, Anastasia, ebevhan, rupprecht, kristof.beyls, yaxunl.
Herald added a reviewer: jhenderson.
Herald added a reviewer: MaskRay.
Herald added a project: LLVM.
JuunChen requested review of this revision.

Problem
-------

!image <https://user-images.githubusercontent.com/13558319/93706082-701d9400-fb55-11ea-8d34-d72a9f75ec48.png>

I used the same `llvm-objdump -S -m --section=<section name> <macho-file>` command for two different macho files to see the disassembly code.
But the annotation for the assembly instruction can't show for the second file,  as shown on the right.

Here is the two files which you can test:
the two macho files.zip <https://github.com/intel/llvm/files/5251278/the.two.macho.files.zip>

Reason
------

I found this to be a bug if the adrp's imm < 0,  at the followed lines:

  adrp_imm = ((info->adrp_inst & 0x00ffffe0) >> 3) | ((info->adrp_inst >> 29) & 0x3);
  if (info->adrp_inst & 0x0200000)
       adrp_imm |= 0xfffffffffc000000LL;

The line adrp_imm = ((info->adrp_inst & 0x00ffffe0) >> 3) | ((info->adrp_inst >> 29) & 0x3) find the adrp_imm in adrp_inst, it's right.
And the next two lines are intended to:

1. Determine if adrp_imm is a negative number
2. if the adrp_imm is negative , adrp_imms's 64-bit complement is calculated

However, as shown in the picture:
!image <https://user-images.githubusercontent.com/13558319/93705478-52016500-fb50-11ea-8cc1-6b82c8bdeb17.png>
adrp_imm is encoded as [23:5][31:29].

If you want to determine if adrp_imm is a negative number, you should determine the 23rd bit of adrp_inst, or the 20th bit of adrp_imm.
It will not be info->adrp_inst & 0x0200000. The 0x0200000 is 0b00000000001000000000000000000000，the code is to determine the 21st of adrp_inst，so it doesn't make any sense.
This code `adrp_imm |= 0xfffffffffc000000LL` is also wrong, it caculated the wrong bits.

Fix
---

Use the follow code to fix:

  if (adrp_imm & (1 << (21 - 1)))
         adrp_imm |= ~((1LL << 21) - 1);



validation
----------

After the correction, I got the result I wanted.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87986

Files:
  llvm/tools/llvm-objdump/MachODump.cpp


Index: llvm/tools/llvm-objdump/MachODump.cpp
===================================================================
--- llvm/tools/llvm-objdump/MachODump.cpp
+++ llvm/tools/llvm-objdump/MachODump.cpp
@@ -7083,8 +7083,8 @@
 
     adrp_imm =
         ((info->adrp_inst & 0x00ffffe0) >> 3) | ((info->adrp_inst >> 29) & 0x3);
-    if (info->adrp_inst & 0x0200000)
-      adrp_imm |= 0xfffffffffc000000LL;
+    if (adrp_imm & (1 << (21 - 1)))
+      adrp_imm |= ~((1LL << 21) - 1);
 
     addxri_inst = ReferenceValue;
     addxri_imm = (addxri_inst >> 10) & 0xfff;
@@ -7113,8 +7113,8 @@
 
     adrp_imm =
         ((info->adrp_inst & 0x00ffffe0) >> 3) | ((info->adrp_inst >> 29) & 0x3);
-    if (info->adrp_inst & 0x0200000)
-      adrp_imm |= 0xfffffffffc000000LL;
+    if (adrp_imm & (1 << (21 - 1)))
+      adrp_imm |= ~((1LL << 21) - 1);
 
     ldrxui_inst = ReferenceValue;
     ldrxui_imm = (ldrxui_inst >> 10) & 0xfff;


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