[PATCH] D139407: [llvm-objdump][AArch64] Fix ADRP target label calculation

[Kristina Bessonova via Phabricator via llvm-commits]

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This patch makes ADRP target label address calculations the same as
label address calculations (see AArch64InstPrinter::printAdrpLabel()).

Otherwise the target label looks misleading as ADRP's immediate offset is,
actually, not an offset to this PC, but an offset to the current PC's
page address in pages.

See for example, `llvm-objdump/ELF/AArch64/pcrel-address.yaml`.
Before this patch the target label `<_start+0x80>` represents the
address `0x200100 + 0x80` while `0x220000` is expected.

Note that with this patch llvm-objdump output matches GNU objdump.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D139407

Files:
  llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.cpp
  llvm/test/tools/llvm-objdump/ELF/AArch64/pcrel-address.yaml


Index: llvm/test/tools/llvm-objdump/ELF/AArch64/pcrel-address.yaml
===================================================================
--- llvm/test/tools/llvm-objdump/ELF/AArch64/pcrel-address.yaml
+++ llvm/test/tools/llvm-objdump/ELF/AArch64/pcrel-address.yaml
@@ -2,7 +2,7 @@
 # RUN: llvm-objdump %t -d --no-show-raw-insn --no-leading-addr | FileCheck %s
 
 # CHECK-LABEL: <_start>:
-# CHECK-NEXT:    adrp x2, 0x220000 <_start+0x80>
+# CHECK-NEXT:    adrp x2, 0x220000 <_start+0x1ff00>
 
 --- !ELF
 FileHeader:
@@ -16,10 +16,6 @@
     Address: 0x200100
     Flags:   [SHF_ALLOC, SHF_EXECINSTR]
     Content: '02010090'
-  - Name:    .data
-    Type:    SHT_PROGBITS
-    Flags:   [SHF_ALLOC, SHF_WRITE]
-    Address: 0x220000
 Symbols:
   - Name:    _start
     Section: .text
Index: llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.cpp
===================================================================
--- llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.cpp
+++ llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.cpp
@@ -412,8 +412,11 @@
     const auto &Desc = Info->get(Inst.getOpcode());
     for (unsigned i = 0, e = Inst.getNumOperands(); i != e; i++) {
       if (Desc.OpInfo[i].OperandType == MCOI::OPERAND_PCREL) {
-        int64_t Imm = Inst.getOperand(i).getImm() * 4;
-        Target = Addr + Imm;
+        int64_t Imm = Inst.getOperand(i).getImm();
+        if (Inst.getOpcode() == AArch64::ADRP)
+          Target = (Addr & -4096) + Imm * 4096;
+        else
+          Target = Addr + Imm * 4;
         return true;
       }
     }


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