[PATCH] D23053: [COFF][ARM] Clear the J1 and J2 bits when applying relocations to 24 bit branches

[Martin Storsjö via llvm-commits]

mstorsjo updated the summary for this revision.
mstorsjo updated this revision to Diff 66905.
mstorsjo added a comment.

Updated the comment and the summary text


https://reviews.llvm.org/D23053

Files:
  COFF/Chunks.cpp
  test/COFF/reloc-arm.test

Index: test/COFF/reloc-arm.test
===================================================================
--- test/COFF/reloc-arm.test
+++ test/COFF/reloc-arm.test
@@ -9,7 +9,7 @@
 # CHECK: 402030 fe07e62f 00000000 00000000 00000000
 # CHECK: 402040 3e04de2f 00000000 00000000 00000000
 # CHECK: 402050 fe07d62f 00000000 00000000 00000000
-# CHECK: 402060 00000000 00000000 00000000 00000000
+# CHECK: 402060 fef0cef7 00000000 00000000 00000000
 
 --- !COFF
 header:
@@ -23,7 +23,7 @@
   - Name:            .text
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_PURGEABLE, IMAGE_SCN_MEM_16BIT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
     Alignment:       4096
-    SectionData:     00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+    SectionData:     00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000f000f8000000000000000000000000
     Relocations:
       - VirtualAddress:  0
         SymbolName:      foo
@@ -43,6 +43,9 @@
       - VirtualAddress:  80
         SymbolName:      foo
         Type:            21  # IMAGE_REL_AMD64_BLX23T
+      - VirtualAddress:  96
+        SymbolName:      bar
+        Type:            20  # IMAGE_REL_ARM_BRANCH24T
 symbols:
   - Name:            .aaa
     Value:           0
@@ -68,4 +71,10 @@
     SimpleType:      IMAGE_SYM_TYPE_NULL
     ComplexType:     IMAGE_SYM_DTYPE_NULL
     StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            bar
+    Value:           0x500000
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
 ...
Index: COFF/Chunks.cpp
===================================================================
--- COFF/Chunks.cpp
+++ COFF/Chunks.cpp
@@ -103,7 +103,8 @@
   uint32_t J1 = ((~V >> 23) & 1) ^ S;
   uint32_t J2 = ((~V >> 22) & 1) ^ S;
   or16(Off, (S << 10) | ((V >> 12) & 0x3ff));
-  or16(Off + 2, (J1 << 13) | (J2 << 11) | ((V >> 1) & 0x7ff));
+  // Clear out the J1 and J2 bits which may be set.
+  write16le(Off + 2, (read16le(Off + 2) & 0xd000) | (J1 << 13) | (J2 << 11) | ((V >> 1) & 0x7ff));
 }
 
 void SectionChunk::applyRelARM(uint8_t *Off, uint16_t Type, Defined *Sym,


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