[lld] [LLD][COFF] Fix ARM64X CHPE exception data size relocation when no x86 .pdata is present (PR #144085)

[Jacek Caban via llvm-commits]

https://github.com/cjacek created https://github.com/llvm/llvm-project/pull/144085

Fixes an issue where we incorrectly skip setting the relocation value if `hybridPdata.first` is null.

>From a8c288f7d72555c20c9cbf7ba4ea139857329f48 Mon Sep 17 00:00:00 2001
From: Jacek Caban <jacek at codeweavers.com>
Date: Fri, 13 Jun 2025 16:25:31 +0200
Subject: [PATCH] [LLD][COFF] Fix ARM64X CHPE exception data size relocation
 when no x86 .pdata is present

Fixes an issue where we incorrectly skip setting the relocation value if `hybridPdata.first` is null.
---
 lld/COFF/Writer.cpp              | 16 +++-------
 lld/test/COFF/pdata-arm64ec.test | 53 ++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 11 deletions(-)

diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index cb9d0001015bd..5f1da5e79daca 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -2495,22 +2495,16 @@ void Writer::setECSymbols() {
               offsetof(data_directory, Size),
           ctx.symtab.edataEnd->getRVA() - ctx.symtab.edataStart->getRVA() +
               ctx.symtab.edataEnd->getSize());
-    if (hybridPdata.first) {
+    if (hybridPdata.first)
       ctx.dynamicRelocs->set(
           dataDirOffset64 + EXCEPTION_TABLE * sizeof(data_directory) +
               offsetof(data_directory, Size),
           hybridPdata.last->getRVA() - hybridPdata.first->getRVA() +
               hybridPdata.last->getSize());
-      if (chpeSym) {
-        size_t size = 0;
-        if (pdata.first)
-          size = pdata.last->getRVA() + pdata.last->getSize() -
-                 pdata.first->getRVA();
-        ctx.dynamicRelocs->set(chpeSym->getRVA() +
-                                   offsetof(chpe_metadata, ExtraRFETableSize),
-                               size);
-      }
-    }
+    if (chpeSym && pdata.first)
+      ctx.dynamicRelocs->set(
+          chpeSym->getRVA() + offsetof(chpe_metadata, ExtraRFETableSize),
+          pdata.last->getRVA() + pdata.last->getSize() - pdata.first->getRVA());
   }
 }
 
diff --git a/lld/test/COFF/pdata-arm64ec.test b/lld/test/COFF/pdata-arm64ec.test
index cf59330b23543..6bdcc5c5682bd 100644
--- a/lld/test/COFF/pdata-arm64ec.test
+++ b/lld/test/COFF/pdata-arm64ec.test
@@ -80,10 +80,63 @@ DIR3-NEXT:     ExtraRFETableSize: 0x10
 DIR3:        ]
 DIR3:      }
 
+arm64x with no x86 .pdata:
+
 RUN: llvm-objdump -s --section=.pdata test4.dll | FileCheck -check-prefix=DATA4 %s
 DATA4: 180006000 00100000 11000001 00200000 11000001  ......... ......
 DATA4: 180006010 00300000 0e300000
 
+RUN: lld-link -out:testx2.dll -machine:arm64x arm64-func-sym.obj arm64ec-func-sym.obj \
+RUN:          loadconfig-arm64.obj loadconfig-arm64ec.obj -dll -noentry
+
+RUN: llvm-readobj --headers --coff-load-config testx2.dll | FileCheck -check-prefix=DIR4 %s
+DIR4:      ImageOptionalHeader {
+DIR4:        DataDirectory {
+DIR4:          ExceptionTableRVA: 0x5000
+DIR4-NEXT:     ExceptionTableSize: 0x10
+DIR4:        }
+DIR4:      }
+DIR4:      CHPEMetadata [
+DIR4:        ExtraRFETable: 0x0
+DIR4-NEXT:   ExtraRFETableSize: 0x0
+DIR4:      ]
+DIR4:      HybridObject {
+DIR4:        ImageOptionalHeader {
+DIR4:          ExceptionTableRVA: 0x0
+DIR4-NEXT:     ExceptionTableSize: 0x0
+DIR4:        }
+DIR4:        CHPEMetadata [
+DIR4:          ExtraRFETable: 0x5000
+DIR4-NEXT:     ExtraRFETableSize: 0x10
+DIR4:        ]
+DIR4:      }
+
+arm64x with no ARM .pdata:
+
+RUN: lld-link -out:testx3.dll -machine:arm64x x86_64-func-sym.obj loadconfig-arm64.obj loadconfig-arm64ec.obj -dll -noentry
+
+RUN: llvm-readobj --headers --coff-load-config testx3.dll | FileCheck -check-prefix=DIR5 %s
+DIR5:      ImageOptionalHeader {
+DIR5:        DataDirectory {
+DIR5:          ExceptionTableRVA: 0x0
+DIR5-NEXT:     ExceptionTableSize: 0x0
+DIR5:        }
+DIR5:      }
+DIR5:      CHPEMetadata [
+DIR5:        ExtraRFETable: 0x4000
+DIR5-NEXT:   ExtraRFETableSize: 0xC
+DIR5:      ]
+DIR5:      HybridObject {
+DIR5:        ImageOptionalHeader {
+DIR5:          ExceptionTableRVA: 0x4000
+DIR5-NEXT:     ExceptionTableSize: 0xC
+DIR5:        }
+DIR5:        CHPEMetadata [
+DIR5:          ExtraRFETable: 0x0
+DIR5-NEXT:     ExtraRFETableSize: 0x0
+DIR5:        ]
+DIR5:      }
+
 Order of inputs doesn't matter, the data is sorted by type and RVA:
 
 RUN: lld-link -out:test5.dll -machine:arm64ec x86_64-func-sym.obj arm64ec-func-sym.obj \