[llvm-bugs] [Bug 52378] New: [aarch64-windows] Invalid code generation: wrong immediate value in adrp instruction

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Mon Nov 1 19:56:59 PDT 2021


            Bug ID: 52378
           Summary: [aarch64-windows] Invalid code generation: wrong
                    immediate value in adrp instruction
           Product: new-bugs
           Version: 12.0
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: roman.zelenyi at gmail.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

Created attachment 25414
  --> https://bugs.llvm.org/attachment.cgi?id=25414&action=edit
Repro case source code

Switch jump table offset in object file is generated relatively to the
beginning of the code section. If the offset is too big to fit in 21-bit, no
error is reported - the value is just silently stripped of the most significant
As a result, this adrp instruction in the linked executable contains an invalid
page offset  value.

A small buildable repro case has been attached. Here is an excerpt from the
repro.o disassembly:

?same@@YAHH at Z (int __cdecl same(int)):
  0000000000200004: 90000209  adrp        x9,.text+#0x40 ; <-- wrong offset!
  0000000000200008: 2A0003E8  mov         w8,w0
  000000000020000C: 91010129  add         x9,x9,.text+#0x40
  0000000000200010: 1000008A  adr         x10,0000000000200020
  0000000000200014: 3868692B  ldrb        w11,[x9,x8]
  0000000000200018: 8B0B094A  add         x10,x10,x11,lsl #2
  000000000020001C: D61F0140  br          x10
  0000000000200020: 14000000  b           ??$int_c@$0A@@@YAHXZ
  0000000000200024: 14000000  b           ??$int_c@$00@@YAHXZ
  0000000000200028: 14000000  b           ??$int_c@$01@@YAHXZ
  000000000020002C: 14000000  b           ??$int_c@$02@@YAHXZ
  0000000000200030: 14000000  b           ??$int_c@$03@@YAHXZ
  0000000000200034: 14000000  b           ??$int_c@$04@@YAHXZ
  0000000000200038: 14000000  b           ??$int_c@$05@@YAHXZ
  000000000020003C: 14000000  b           ??$int_c@$06@@YAHXZ
  0000000000200040: 03020100 ; <-- jump table 
  0000000000200044: 07060504

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