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

[YAMAMOTO Takashi via llvm-commits]

https://github.com/yamt updated https://github.com/llvm/llvm-project/pull/153763

>From 3f65a783f2064a9040f8fcbfddfc3072c52493d8 Mon Sep 17 00:00:00 2001
From: YAMAMOTO Takashi <yamamoto at midokura.com>
Date: Fri, 15 Aug 2025 17:15:22 +0900
Subject: [PATCH 1/3] [lld][WebAssembly] Do not relocate ABSOLUTE symbols

Fixes https://github.com/llvm/llvm-project/issues/153759
---
 lld/wasm/SyntheticSections.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index e1192706ea913..6c1c4391ea0d7 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -442,6 +442,8 @@ void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
   for (const Symbol *sym : internalGotSymbols) {
     if (TLS != sym->isTLS())
       continue;
+    if (sym->flags & WASM_SYMBOL_ABSOLUTE)
+      continue;
 
     if (auto *d = dyn_cast<DefinedData>(sym)) {
       // Get __memory_base
@@ -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();

>From 7cdff15342a8645701fdc1a690a4dc210fb491d6 Mon Sep 17 00:00:00 2001
From: YAMAMOTO Takashi <yamamoto at midokura.com>
Date: Mon, 18 Aug 2025 10:08:15 +0900
Subject: [PATCH 2/3] add a test

---
 lld/test/wasm/pie.s | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/lld/test/wasm/pie.s b/lld/test/wasm/pie.s
index 21eac79207318..cac54f887e417 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 +41,11 @@ foo:
   drop
 
   global.get __stack_pointer
+  i32.load 0
+  call_indirect  () -> (i32)
+  drop
+
+  global.get __wasm_first_page_end at GOT
   end_function
 
 get_data_address:
@@ -145,6 +150,18 @@ _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 +190,23 @@ _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:

>From 08fde9693e0fe06e8530312331790a4107acad83 Mon Sep 17 00:00:00 2001
From: YAMAMOTO Takashi <yamamoto at midokura.com>
Date: Mon, 18 Aug 2025 10:24:10 +0900
Subject: [PATCH 3/3] check ABSOLUTE before TLS

---
 lld/wasm/SyntheticSections.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lld/wasm/SyntheticSections.cpp b/lld/wasm/SyntheticSections.cpp
index 6c1c4391ea0d7..e26f818fc2ca0 100644
--- a/lld/wasm/SyntheticSections.cpp
+++ b/lld/wasm/SyntheticSections.cpp
@@ -440,10 +440,10 @@ void GlobalSection::generateRelocationCode(raw_ostream &os, bool TLS) const {
                                  : WASM_OPCODE_I32_ADD;
 
   for (const Symbol *sym : internalGotSymbols) {
-    if (TLS != sym->isTLS())
-      continue;
     if (sym->flags & WASM_SYMBOL_ABSOLUTE)
       continue;
+    if (TLS != sym->isTLS())
+      continue;
 
     if (auto *d = dyn_cast<DefinedData>(sym)) {
       // Get __memory_base