[llvm] [llvm-dwarfdump] Fix parsing DW_CFA_AARCH64_negate_ra_state (PR #84128)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-debuginfo

Author: Igor Kudrin (igorkudrin)

<details>
<summary>Changes</summary>

The saved state of the AARCH64_DWARF_PAUTH_RA_STATE register was not updated, so `llvm-dwarfdump` continued to dump it as `reg34=1` even if the correct value is `0`:

```
> llvm-dwarfdump -v test.o
...
0000002c 00000024 00000030 FDE cie=00000000 pc=00000030...00000064
  Format:       DWARF32
  DW_CFA_advance_loc: 4
  DW_CFA_AARCH64_negate_ra_state:
  DW_CFA_advance_loc: 4
  DW_CFA_def_cfa_offset: +16
  DW_CFA_offset: W30 -16
  DW_CFA_remember_state:
  DW_CFA_advance_loc: 16
  DW_CFA_def_cfa_offset: +0
  DW_CFA_advance_loc: 4
  DW_CFA_AARCH64_negate_ra_state:
  DW_CFA_restore: W30
  DW_CFA_advance_loc: 4
  DW_CFA_restore_state:
  DW_CFA_advance_loc: 12
  DW_CFA_def_cfa_offset: +0
  DW_CFA_advance_loc: 4
  DW_CFA_AARCH64_negate_ra_state:
  DW_CFA_restore: W30
  DW_CFA_nop:

  0x30: CFA=WSP
  0x34: CFA=WSP: reg34=1
  0x38: CFA=WSP+16: W30=[CFA-16], reg34=1
  0x48: CFA=WSP: W30=[CFA-16], reg34=1
  0x4c: CFA=WSP: reg34=1               <--- should be '=0'
  0x50: CFA=WSP+16: W30=[CFA-16], reg34=1
  0x5c: CFA=WSP: W30=[CFA-16], reg34=1
  0x60: CFA=WSP: reg34=1               <--- should be '=0'
```

---
Full diff: https://github.com/llvm/llvm-project/pull/84128.diff


2 Files Affected:

- (modified) llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp (+2) 
- (modified) llvm/test/CodeGen/AArch64/sign-return-address-cfi-negate-ra-state.ll (+19) 


``````````diff
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
index aae1668c1639c4..0c968703f80b0d 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
@@ -630,6 +630,8 @@ Error UnwindTable::parseRows(const CFIProgram &CFIP, UnwindRow &Row,
           if (LRLoc->getLocation() == UnwindLocation::Constant) {
             // Toggle the constant value from 0 to 1 or 1 to 0.
             LRLoc->setConstant(LRLoc->getConstant() ^ 1);
+            Row.getRegisterLocations().setRegisterLocation(
+                AArch64DWARFPAuthRaState, *LRLoc);
           } else {
             return createStringError(
                 errc::invalid_argument,
diff --git a/llvm/test/CodeGen/AArch64/sign-return-address-cfi-negate-ra-state.ll b/llvm/test/CodeGen/AArch64/sign-return-address-cfi-negate-ra-state.ll
index da2c2985acf971..9464e3447993b3 100644
--- a/llvm/test/CodeGen/AArch64/sign-return-address-cfi-negate-ra-state.ll
+++ b/llvm/test/CodeGen/AArch64/sign-return-address-cfi-negate-ra-state.ll
@@ -213,6 +213,10 @@ attributes #0 = { "sign-return-address"="all" }
 ; CHECK-DUMP-NOT: DW_CFA_remember_state
 ; CHECK-DUMP-NOT: DW_CFA_restore_state
 
+; CHECK-DUMP: CFA=WSP{{$}}
+; CHECK-DUMP: reg34=1
+; CHECK-DUMP-NOT: reg34=0
+
 ; baz_async
 ; CHECK-DUMP-LABEL: FDE
 ; CHECK-DUMP: Format:       DWARF32
@@ -222,9 +226,24 @@ attributes #0 = { "sign-return-address"="all" }
 ; CHECK-DUMP:   DW_CFA_restore_state:
 ; CHECK-DUMP:   DW_CFA_AARCH64_negate_ra_state:
 
+; CHECK-DUMP: CFA=WSP{{$}}
+;; First DW_CFA_AARCH64_negate_ra_state:
+; CHECK-DUMP: reg34=1
+;; Second DW_CFA_AARCH64_negate_ra_state:
+; CHECK-DUMP: reg34=0
+;; DW_CFA_restore_state:
+; CHECK-DUMP: reg34=1
+;; Third DW_CFA_AARCH64_negate_ra_state:
+; CHECK-DUMP: reg34=0
+; CHECK-DUMP-NOT: reg34=
+
 ; baz_sync
 ; CHECK-DUMP-LABEL: FDE
 ; CHECK-DUMP:   DW_CFA_AARCH64_negate_ra_state:
 ; CHECK-DUMP-NOT: DW_CFA_AARCH64_negate_ra_state
 ; CHECK-DUMP-NOT: DW_CFA_remember_state
 ; CHECK-DUMP-NOT: DW_CFA_restore_state
+
+; CHECK-DUMP: CFA=WSP{{$}}
+; CHECK-DUMP: reg34=1
+; CHECK-DUMP-NOT: reg34=0

``````````

</details>


https://github.com/llvm/llvm-project/pull/84128