[Object][WebAssembly] Fix data segment offsets higher than 2^31

[sbc100]

Fixes: #58555

[llvmbot]

@llvm/pr-subscribers-backend-webassembly

@llvm/pr-subscribers-llvm-binary-utilities

Author: Sam Clegg (sbc100)

Changes

Fixes: #58555

---

Full diff: https://github.com/llvm/llvm-project/pull/125739.diff

3 Files Affected:

• (modified) llvm/include/llvm/BinaryFormat/Wasm.h (+2-2)
• (modified) llvm/lib/Object/WasmObjectFile.cpp (+2-2)
• (added) llvm/test/Object/Wasm/data-offsets.yaml (+16)

diff --git a/llvm/include/llvm/BinaryFormat/Wasm.h b/llvm/include/llvm/BinaryFormat/Wasm.h
index ede2d692a594916..30271be232ca773 100644
--- a/llvm/include/llvm/BinaryFormat/Wasm.h
+++ b/llvm/include/llvm/BinaryFormat/Wasm.h
@@ -333,8 +333,8 @@ struct WasmTable {
 struct WasmInitExprMVP {
   uint8_t Opcode;
   union {
-    int32_t Int32;
-    int64_t Int64;
+    uint32_t Int32;
+    uint64_t Int64;
     uint32_t Float32;
     uint64_t Float64;
     uint32_t Global;
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 0f6fd5612f9d82a..7815c2670223198 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -201,10 +201,10 @@ static Error readInitExpr(wasm::WasmInitExpr &Expr,
   Expr.Inst.Opcode = readOpcode(Ctx);
   switch (Expr.Inst.Opcode) {
   case wasm::WASM_OPCODE_I32_CONST:
-    Expr.Inst.Value.Int32 = readVarint32(Ctx);
+    Expr.Inst.Value.Int32 = readVaruint32(Ctx);
     break;
   case wasm::WASM_OPCODE_I64_CONST:
-    Expr.Inst.Value.Int64 = readVarint64(Ctx);
+    Expr.Inst.Value.Int64 = readVaruint64(Ctx);
     break;
   case wasm::WASM_OPCODE_F32_CONST:
     Expr.Inst.Value.Float32 = readFloat32(Ctx);
diff --git a/llvm/test/Object/Wasm/data-offsets.yaml b/llvm/test/Object/Wasm/data-offsets.yaml
new file mode 100644
index 000000000000000..26b2be2b78f5323
--- /dev/null
+++ b/llvm/test/Object/Wasm/data-offsets.yaml
@@ -0,0 +1,16 @@
+# RUN: yaml2obj %s | llvm-objdump -s -
+
+## Tests data offsets above 2**31
+
+--- !WASM
+FileHeader:
+  Version:         0x00000001
+Sections:
+  - Type:            DATA
+    Segments:
+      - SectionOffset:   0
+        InitFlags:       0
+        Offset:
+          Opcode:          I32_CONST
+          Value:           2147483649
+        Content:         '6401020304'

[dschuff]

For wasm64, could there be offsets higher than 2^32? Or are those just speced to be varint64?

[sbc100]

For wasm64, could there be offsets higher than 2^32? Or are those just speced to be varint64?

Yup, that should work. Do you want me to add a testing for that?

[dschuff]

Yeah, that seems like we should have that if we don't already.

[dschuff]

otherwise LGTM