[llvm-branch-commits] [lld] a760d7c - [LLD] [COFF] Fix handling of immediates in ARM64_SECREL_HIGH12A (#200060)

[Cullen Rhodes via llvm-branch-commits]

Author: Martin Storsjö
Date: 2026-06-01T07:17:28Z
New Revision: a760d7c07024feaf3b58212edd388a4f016a71ce

URL: https://github.com/llvm/llvm-project/commit/a760d7c07024feaf3b58212edd388a4f016a71ce
DIFF: https://github.com/llvm/llvm-project/commit/a760d7c07024feaf3b58212edd388a4f016a71ce.diff

LOG: [LLD] [COFF] Fix handling of immediates in ARM64_SECREL_HIGH12A (#200060)

Just like for PAGEBASE_REL21, the immediate in SECREL_HIGH12A is the
byte offset, not a page offset. The byte level offset is added to the
symbol offset, which only then after that gets shifted right by 12. This
makes the handling of this immediate consistent with what MS link.exe
does.

The existing testcase had a zero immediate in the instruction for this
relocation.

This makes it clear that immediate offsets with SECREL_HIGH12A do work
fine, where the byte level offsets end up carrying over to the upper
bits.

(cherry picked from commit 5c95f6a859394757b92b0d63ff90b9175056deb6)

Added: 
    

Modified: 
    lld/COFF/Chunks.cpp
    lld/test/COFF/arm64-relocs-imports.test

Removed: 
    


################################################################################
diff  --git a/lld/COFF/Chunks.cpp b/lld/COFF/Chunks.cpp
index 409491d4a1f89..efc9ff113e623 100644
--- a/lld/COFF/Chunks.cpp
+++ b/lld/COFF/Chunks.cpp
@@ -300,13 +300,16 @@ static void applySecRelHigh12A(const SectionChunk *sec, uint8_t *off,
                                OutputSection *os, uint64_t s) {
   if (!checkSecRel(sec, os))
     return;
-  uint64_t secRel = (s - os->getRVA()) >> 12;
-  if (0xfff < secRel) {
+  uint32_t orig = read32le(off);
+  uint64_t imm = (orig >> 10) & 0xFFF;
+  orig &= ~(0xFFF << 10);
+  imm = (s + imm - os->getRVA()) >> 12;
+  if (0xfff < imm) {
     error("overflow in SECREL_HIGH12A relocation in section: " +
           sec->getSectionName());
     return;
   }
-  applyArm64Imm(off, secRel & 0xfff, 0);
+  write32le(off, orig | (imm << 10));
 }
 
 static void applySecRelLdr(const SectionChunk *sec, uint8_t *off,

diff  --git a/lld/test/COFF/arm64-relocs-imports.test b/lld/test/COFF/arm64-relocs-imports.test
index da2fd1f941d8a..c048a570674c7 100644
--- a/lld/test/COFF/arm64-relocs-imports.test
+++ b/lld/test/COFF/arm64-relocs-imports.test
@@ -39,8 +39,8 @@
 # BEFORE:       74:       00000000        udf #0
 # BEFORE:       78:       00000001        udf #1
 # BEFORE:       7c:       00000001        udf #1
-# BEFORE:       80:       91000000        add     x0, x0, #0
-# BEFORE:       84:       91400000        add     x0, x0, #0, lsl #12
+# BEFORE:       80:       913c0000        add     x0, x0, #3840
+# BEFORE:       84:       917c0000        add     x0, x0, #3840, lsl #12
 # BEFORE:       88:       f9400000        ldr     x0, [x0]
 # BEFORE:       8c:       00000001        udf #1
 # BEFORE:       90:       30091a20        adr x0, 0x123d5
@@ -83,8 +83,8 @@
 # AFTER:  140001074:      00000001        udf #1
 # AFTER:  140001078:      00002009        udf #8201
 # AFTER:  14000107c:      00000009        udf #9
-# AFTER:  140001080:      910e2000        add     x0, x0, #904
-# AFTER:  140001084:      91400400        add     x0, x0, #1, lsl #12
+# AFTER:  140001080:      910a2000        add     x0, x0, #648
+# AFTER:  140001084:      91400800        add     x0, x0, #2, lsl #12
 # AFTER:  140001088:      f941c400        ldr     x0, [x0, #904]
 # AFTER:  14000108c:      00000003        udf #3
 # AFTER:  140001090:      300995e0        adr     x0, 0x14001434d
@@ -104,7 +104,7 @@ sections:
   - Name:            .text
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
     Alignment:       4
-    SectionData:     FE0F1FF80000009000080091000000940001403900014079000140B9000140F90001003900010079000100B9000100F90001403D0001407D000140BD000140FD0001C03D0001003D0001007D000100BD000100FD0001803D000540F9201A01B000FC4FF9E0031F2AFE0741F8C0035FD6080000000000000001000000010000000000009100004091000040f901000000201a093001000054000000360100000002008090
+    SectionData:     FE0F1FF80000009000080091000000940001403900014079000140B9000140F90001003900010079000100B9000100F90001403D0001407D000140BD000140FD0001C03D0001003D0001007D000100BD000100FD0001803D000540F9201A01B000FC4FF9E0031F2AFE0741F8C0035FD60800000000000000010000000100000000003C9100007C91000040f901000000201a093001000054000000360100000002008090
     Relocations:
       - VirtualAddress:  4
         SymbolName:      .Lstr