[llvm] 028a261 - [XCOFF] FixupOffsetInCsect should be 0 for R_REF relocation.

[via llvm-commits]

Author: esmeyi
Date: 2023-06-15T01:28:45-04:00
New Revision: 028a261350baf734db20a65b413ee07d7d4f7b1b

URL: https://github.com/llvm/llvm-project/commit/028a261350baf734db20a65b413ee07d7d4f7b1b
DIFF: https://github.com/llvm/llvm-project/commit/028a261350baf734db20a65b413ee07d7d4f7b1b.diff

LOG: [XCOFF] FixupOffsetInCsect should be 0 for R_REF relocation.

Summary: The FixupOffsetInCsect should be 0 for R_REF relocation since it specifies a nonrelocating reference. Otherwise liker would try to relocate the symbol through its address and an error like following occurred.
```
ld: 0711-547 SEVERE ERROR: Object /tmp/1-2a7ea1.o cannot be processed.
	RLD address 0x65 for section 2 (.data) is
	not contained in the section.
```

Reviewed By: shchenz

Differential Revision: https://reviews.llvm.org/D152777

Added: 
    

Modified: 
    llvm/lib/MC/XCOFFObjectWriter.cpp
    llvm/test/CodeGen/PowerPC/pgo-ref-directive.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/XCOFFObjectWriter.cpp b/llvm/lib/MC/XCOFFObjectWriter.cpp
index 4b426604c0957..9baf0b35593c9 100644
--- a/llvm/lib/MC/XCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/XCOFFObjectWriter.cpp
@@ -618,6 +618,12 @@ void XCOFFObjectWriter::recordRelocation(MCAssembler &Asm,
   assert(SectionMap.contains(SymASec) &&
          "Expected containing csect to exist in map.");
 
+  assert((Fixup.getOffset() <=
+          MaxRawDataSize - Layout.getFragmentOffset(Fragment)) &&
+         "Fragment offset + fixup offset is overflowed.");
+  uint32_t FixupOffsetInCsect =
+      Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+
   const uint32_t Index = getIndex(SymA, SymASec);
   if (Type == XCOFF::RelocationType::R_POS ||
       Type == XCOFF::RelocationType::R_TLS)
@@ -656,23 +662,18 @@ void XCOFFObjectWriter::recordRelocation(MCAssembler &Asm,
 
     // The address of the branch instruction should be the sum of section
     // address, fragment offset and Fixup offset.
-    uint64_t BRInstrAddress = SectionMap[ParentSec]->Address +
-                              Layout.getFragmentOffset(Fragment) +
-                              Fixup.getOffset();
+    uint64_t BRInstrAddress =
+        SectionMap[ParentSec]->Address + FixupOffsetInCsect;
     // The FixedValue should be the 
diff erence between SymA csect address and BR
     // instr address plus any constant value.
     FixedValue =
         SectionMap[SymASec]->Address - BRInstrAddress + Target.getConstant();
-  } else if (Type == XCOFF::RelocationType::R_REF)
-    // The FixedValue should always be 0 since it specifies a nonrelocating
-    // reference.
+  } else if (Type == XCOFF::RelocationType::R_REF) {
+    // The FixedValue and FixupOffsetInCsect should always be 0 since it
+    // specifies a nonrelocating reference.
     FixedValue = 0;
-
-  assert((Fixup.getOffset() <=
-          MaxRawDataSize - Layout.getFragmentOffset(Fragment)) &&
-         "Fragment offset + fixup offset is overflowed.");
-  uint32_t FixupOffsetInCsect =
-      Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+    FixupOffsetInCsect = 0;
+  }
 
   XCOFFRelocation Reloc = {Index, FixupOffsetInCsect, SignAndSize, Type};
   MCSectionXCOFF *RelocationSec = cast<MCSectionXCOFF>(Fragment->getParent());

diff  --git a/llvm/test/CodeGen/PowerPC/pgo-ref-directive.ll b/llvm/test/CodeGen/PowerPC/pgo-ref-directive.ll
index 201af2f949618..dd421dfe63d02 100644
--- a/llvm/test/CodeGen/PowerPC/pgo-ref-directive.ll
+++ b/llvm/test/CodeGen/PowerPC/pgo-ref-directive.ll
@@ -73,8 +73,8 @@ entry:
 ; NOVNDS-NEXT: .ref __llvm_prf_names[RO]
 ; NOVNDS-NOT:  .ref __llvm_prf_vnds
 
-; NOVNDS-OBJ: 00000008 R_REF  __llvm_prf_data
-; NOVNDS-OBJ: 00000008 R_REF  __llvm_prf_names
+; NOVNDS-OBJ: 00000000 R_REF  __llvm_prf_data
+; NOVNDS-OBJ: 00000000 R_REF  __llvm_prf_names
 ; NOVNDS-OBJ-NOT: R_REF  __llvm_prf_vnds
 
 ;--- with-vnds.ll
@@ -115,8 +115,8 @@ entry:
 
 ; WITHVNDS-OBJ:      RELOCATION RECORDS FOR [.data]:
 ; WITHVNDS-OBJ-NEXT: OFFSET   TYPE                     VALUE
-; WITHVNDS-OBJ-NEXT: 00000008 R_REF                    __llvm_prf_data
-; WITHVNDS-OBJ-NEXT: 00000008 R_REF                    __llvm_prf_names
-; WITHVNDS-OBJ-NEXT: 00000008 R_REF                    __llvm_prf_vnds
+; WITHVNDS-OBJ-NEXT: 00000000 R_REF                    __llvm_prf_data
+; WITHVNDS-OBJ-NEXT: 00000000 R_REF                    __llvm_prf_names
+; WITHVNDS-OBJ-NEXT: 00000000 R_REF                    __llvm_prf_vnds
 ; WITHVNDS-OBJ-NEXT: 00000100 R_POS                    .main
 ; WITHVNDS-OBJ-NEXT: 00000104 R_POS                    TOC