[lld] 9247be8 - [lld][WebAssembly] Do not relocate ABSOLUTE symbols (#153763)

[via llvm-commits]

Author: YAMAMOTO Takashi
Date: 2025-08-18T21:56:48-07:00
New Revision: 9247be8ca0a32ed6c09a212cb36b33d3e56b4921

URL: https://github.com/llvm/llvm-project/commit/9247be8ca0a32ed6c09a212cb36b33d3e56b4921
DIFF: https://github.com/llvm/llvm-project/commit/9247be8ca0a32ed6c09a212cb36b33d3e56b4921.diff

LOG: [lld][WebAssembly] Do not relocate ABSOLUTE symbols (#153763)

Fixes https://github.com/llvm/llvm-project/issues/153759

Added: 
    

Modified: 
    lld/test/wasm/pie.s
    lld/wasm/SyntheticSections.cpp

Removed: 
    


################################################################################
diff  --git a/lld/test/wasm/pie.s b/lld/test/wasm/pie.s
index 21eac79207318..433958e149d8f 100644
--- a/lld/test/wasm/pie.s
+++ b/lld/test/wasm/pie.s
@@ -2,7 +2,7 @@
 # RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-emscripten %S/Inputs/internal_func.s -o %t.internal_func.o
 # RUN: wasm-ld --no-gc-sections --experimental-pic -pie --unresolved-symbols=import-dynamic -o %t.wasm %t.o %t.internal_func.o
 # RUN: obj2yaml %t.wasm | FileCheck %s
-# RUN: llvm-objdump --disassemble-symbols=__wasm_call_ctors,__wasm_apply_data_relocs --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DISASSEM
+# RUN: llvm-objdump --disassemble-symbols=__wasm_call_ctors,__wasm_apply_data_relocs,__wasm_apply_global_relocs --no-show-raw-insn --no-leading-addr %t.wasm | FileCheck %s --check-prefixes DISASSEM
 
 .functype external_func () -> ()
 .functype internal_func1 () -> (i32)
@@ -41,6 +41,9 @@ foo:
   drop
 
   global.get __stack_pointer
+  drop
+
+  global.get __wasm_first_page_end at GOT
   end_function
 
 get_data_address:
@@ -145,6 +148,18 @@ _start:
 # DISASSEM-LABEL:  <__wasm_apply_data_relocs>:
 # DISASSEM:        end
 
+# global 6 is __wasm_first_page_end, which is ABSOLUTE and
+# thus should not be relocated.
+#
+# DISASSEM-LABEL:  <__wasm_apply_global_relocs>:
+# DISASSEM:        global.set      4
+# DISASSEM:        global.set      5
+# DISASSEM-NOT:    global.set      6
+# DISASSEM:        global.set      7
+# DISASSEM:        global.set      8
+# DISASSEM:        global.set      9
+# DISASSEM:        end
+
 # Run the same test with extended-const support.  When this is available
 # we don't need __wasm_apply_global_relocs and instead rely on the add
 # instruction in the InitExpr.  We also, therefore, do not need these globals
@@ -173,17 +188,23 @@ _start:
 # EXTENDED-CONST-NEXT:        Type:            I32
 # EXTENDED-CONST-NEXT:        Mutable:         false
 # EXTENDED-CONST-NEXT:        InitExpr:
+# EXTENDED-CONST-NEXT:          Opcode:        I32_CONST
+# EXTENDED-CONST-NEXT:          Value:         65536
+# EXTENDED-CONST-NEXT:      - Index:           7
+# EXTENDED-CONST-NEXT:        Type:            I32
+# EXTENDED-CONST-NEXT:        Mutable:         false
+# EXTENDED-CONST-NEXT:        InitExpr:
 # EXTENDED-CONST-NEXT:          Extended:        true
 # This instruction sequence decodes to:
 # (global.get[0x23] 0x1 i32.const[0x41] 0x0C i32.add[0x6A] end[0x0b])
 # EXTENDED-CONST-NEXT:          Body:            2301410C6A0B
-# EXTENDED-CONST-NEXT:      - Index:           7
+# EXTENDED-CONST-NEXT:      - Index:           8
 # EXTENDED-CONST-NEXT:        Type:            I32
 # EXTENDED-CONST-NEXT:        Mutable:         false
 # EXTENDED-CONST-NEXT:        InitExpr:
 # EXTENDED-CONST-NEXT:          Opcode:        GLOBAL_GET
 # EXTENDED-CONST-NEXT:          Index:         2
-# EXTENDED-CONST-NEXT:      - Index:           8
+# EXTENDED-CONST-NEXT:      - Index:           9
 # EXTENDED-CONST-NEXT:        Type:            I32
 # EXTENDED-CONST-NEXT:        Mutable:         false
 # EXTENDED-CONST-NEXT:        InitExpr:

diff  --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index e1192706ea913..e26f818fc2ca0 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -440,6 +440,8 @@ void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
                                  : WASM_OPCODE_I32_ADD;
 
   for (const Symbol *sym : internalGotSymbols) {
+    if (sym->flags & WASM_SYMBOL_ABSOLUTE)
+      continue;
     if (TLS != sym->isTLS())
       continue;
 
@@ -503,7 +505,8 @@ void GlobalSection::writeBody() {
     bool useExtendedConst = false;
     uint32_t globalIdx;
     int64_t offset;
-    if (ctx.arg.extendedConst && ctx.isPic) {
+    if (ctx.arg.extendedConst && ctx.isPic &&
+        (sym->flags & WASM_SYMBOL_ABSOLUTE) == 0) {
       if (auto *d = dyn_cast<DefinedData>(sym)) {
         if (!sym->isTLS()) {
           globalIdx = ctx.sym.memoryBase->getGlobalIndex();