[clang] [libunwind] [llvm] [wasm] Toolchain support for `wasm32-wali-linux-musl` target (PR #156087)

Arjun Ramesh via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 5 12:22:20 PDT 2025 

https://github.com/arjunr2 updated https://github.com/llvm/llvm-project/pull/156087

>From cb996a12aa20c65980f620381731fad1622e0417 Mon Sep 17 00:00:00 2001
From: Arjun Ramesh <arjunr2 at andrew.cmu.edu>
Date: Sat, 30 Aug 2025 01:01:02 -0400
Subject: [PATCH 1/4] Support for `wasm32-wali-linux-musl target` in `clang`,
 `lld`, and `libcxx`

---
 clang/lib/Basic/Targets.cpp             |  7 ++++++-
 clang/lib/Basic/Targets/OSTargets.h     | 17 +++++++++++++++++
 clang/lib/Basic/Targets/WebAssembly.h   | 18 +++++++++++++-----
 clang/lib/Driver/Driver.cpp             |  2 ++
 libunwind/src/UnwindRegistersRestore.S  |  7 +++----
 libunwind/src/UnwindRegistersSave.S     |  8 ++++----
 llvm/include/llvm/TargetParser/Triple.h |  7 +++++++
 llvm/lib/TargetParser/Triple.cpp        |  3 +++
 8 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index e3f9760ac7ce3..11222bc836775 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -687,7 +687,8 @@ std::unique_ptr<TargetInfo> AllocateTarget(const llvm::Triple &Triple,
   }
   case llvm::Triple::wasm32:
     if (Triple.getSubArch() != llvm::Triple::NoSubArch ||
-        Triple.getVendor() != llvm::Triple::UnknownVendor ||
+        (!Triple.isWALI() &&
+         Triple.getVendor() != llvm::Triple::UnknownVendor) ||
         !Triple.isOSBinFormatWasm())
       return nullptr;
     switch (os) {
@@ -697,6 +698,10 @@ std::unique_ptr<TargetInfo> AllocateTarget(const llvm::Triple &Triple,
       case llvm::Triple::Emscripten:
       return std::make_unique<EmscriptenTargetInfo<WebAssembly32TargetInfo>>(
           Triple, Opts);
+      // WALI OS target
+      case llvm::Triple::Linux:
+        return std::make_unique<WALITargetInfo<WebAssembly32TargetInfo>>(Triple,
+                                                                         Opts);
       case llvm::Triple::UnknownOS:
       return std::make_unique<WebAssemblyOSTargetInfo<WebAssembly32TargetInfo>>(
           Triple, Opts);
diff --git a/clang/lib/Basic/Targets/OSTargets.h b/clang/lib/Basic/Targets/OSTargets.h
index a733f6e97b3a4..2199bfcfbd7ab 100644
--- a/clang/lib/Basic/Targets/OSTargets.h
+++ b/clang/lib/Basic/Targets/OSTargets.h
@@ -936,6 +936,23 @@ class LLVM_LIBRARY_VISIBILITY WASITargetInfo
   using WebAssemblyOSTargetInfo<Target>::WebAssemblyOSTargetInfo;
 };
 
+// WALI target
+template <typename Target>
+class LLVM_LIBRARY_VISIBILITY WALITargetInfo
+    : public WebAssemblyOSTargetInfo<Target> {
+  void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
+                    MacroBuilder &Builder) const final {
+    WebAssemblyOSTargetInfo<Target>::getOSDefines(Opts, Triple, Builder);
+    // Linux defines; list based off of gcc output
+    DefineStd(Builder, "unix", Opts);
+    DefineStd(Builder, "linux", Opts);
+    Builder.defineMacro("__wali__");
+  }
+
+public:
+  using WebAssemblyOSTargetInfo<Target>::WebAssemblyOSTargetInfo;
+};
+
 // Emscripten target
 template <typename Target>
 class LLVM_LIBRARY_VISIBILITY EmscriptenTargetInfo
diff --git a/clang/lib/Basic/Targets/WebAssembly.h b/clang/lib/Basic/Targets/WebAssembly.h
index eba74229dfc14..81fd40a62d3a3 100644
--- a/clang/lib/Basic/Targets/WebAssembly.h
+++ b/clang/lib/Basic/Targets/WebAssembly.h
@@ -88,12 +88,20 @@ class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
     LongDoubleWidth = LongDoubleAlign = 128;
     LongDoubleFormat = &llvm::APFloat::IEEEquad();
     MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
-    // size_t being unsigned long for both wasm32 and wasm64 makes mangled names
-    // more consistent between the two.
-    SizeType = UnsignedLong;
-    PtrDiffType = SignedLong;
-    IntPtrType = SignedLong;
     HasUnalignedAccess = true;
+    if (T.isWALI()) {
+      // WALI ABI requires 64-bit longs on both wasm32 and wasm64
+      LongAlign = LongWidth = 64;
+      SizeType = UnsignedInt;
+      PtrDiffType = SignedInt;
+      IntPtrType = SignedInt;
+    } else {
+      // size_t being unsigned long for both wasm32 and wasm64 makes mangled
+      // names more consistent between the two.
+      SizeType = UnsignedLong;
+      PtrDiffType = SignedLong;
+      IntPtrType = SignedLong;
+    }
   }
 
   StringRef getABI() const override;
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index f110dbab3e5a5..e99b2263c81c6 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -6833,6 +6833,8 @@ const ToolChain &Driver::getToolChain(const ArgList &Args,
         TC = std::make_unique<toolchains::VEToolChain>(*this, Target, Args);
       else if (Target.isOHOSFamily())
         TC = std::make_unique<toolchains::OHOS>(*this, Target, Args);
+      else if (Target.isWALI())
+        TC = std::make_unique<toolchains::WebAssembly>(*this, Target, Args);
       else
         TC = std::make_unique<toolchains::Linux>(*this, Target, Args);
       break;
diff --git a/libunwind/src/UnwindRegistersRestore.S b/libunwind/src/UnwindRegistersRestore.S
index 5e199188945df..eda0b10205ac3 100644
--- a/libunwind/src/UnwindRegistersRestore.S
+++ b/libunwind/src/UnwindRegistersRestore.S
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__)
+
 #include "assembly.h"
 
 #define FROM_0_TO_15 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
@@ -20,8 +22,6 @@
   .text
 #endif
 
-#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__)
-
 #if defined(__i386__)
 DEFINE_LIBUNWIND_FUNCTION(__libunwind_Registers_x86_jumpto)
 #
@@ -1250,7 +1250,6 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind19Registers_loongarch6jumptoEv)
 
 #endif
 
-#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__) */
-
 NO_EXEC_STACK_DIRECTIVE
 
+#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__) */
diff --git a/libunwind/src/UnwindRegistersSave.S b/libunwind/src/UnwindRegistersSave.S
index 5139a551ad245..a2ff6578b1057 100644
--- a/libunwind/src/UnwindRegistersSave.S
+++ b/libunwind/src/UnwindRegistersSave.S
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__)
+
 #include "assembly.h"
 
 #define FROM_0_TO_15 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
@@ -20,8 +22,6 @@
     .text
 #endif
 
-#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__)
-
 #if defined(__i386__)
 
 #
@@ -1232,6 +1232,6 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
   WEAK_ALIAS(__unw_getcontext, unw_getcontext)
 #endif
 
-#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__) */
-
 NO_EXEC_STACK_DIRECTIVE
+
+#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__) */
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index ede9797ac7488..447a94a48af67 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -199,6 +199,7 @@ class Triple {
     SUSE,
     OpenEmbedded,
     Intel,
+    WALI,
     Meta,
     LastVendorType = Meta
   };
@@ -795,6 +796,12 @@ class Triple {
     return getObjectFormat() == Triple::DXContainer;
   }
 
+  /// Tests whether the target uses WALI Wasm
+  bool isWALI() const {
+    return getArch() == Triple::wasm32 && getVendor() == Triple::WALI &&
+           getOS() == Triple::Linux;
+  }
+
   /// Tests whether the target is the PS4 platform.
   bool isPS4() const {
     return getArch() == Triple::x86_64 &&
diff --git a/llvm/lib/TargetParser/Triple.cpp b/llvm/lib/TargetParser/Triple.cpp
index 6acb0bc49ecfe..5fc0086fc8d76 100644
--- a/llvm/lib/TargetParser/Triple.cpp
+++ b/llvm/lib/TargetParser/Triple.cpp
@@ -277,6 +277,8 @@ StringRef Triple::getVendorTypeName(VendorType Kind) {
   case PC: return "pc";
   case SCEI: return "scei";
   case SUSE: return "suse";
+  case WALI:
+    return "wali";
   case Meta:
     return "meta";
   }
@@ -681,6 +683,7 @@ static Triple::VendorType parseVendor(StringRef VendorName) {
       .Case("suse", Triple::SUSE)
       .Case("oe", Triple::OpenEmbedded)
       .Case("intel", Triple::Intel)
+      .Case("wali", Triple::WALI)
       .Case("meta", Triple::Meta)
       .Default(Triple::UnknownVendor);
 }

>From 2d4f58190d00385986c3fb3cabf0903718978e19 Mon Sep 17 00:00:00 2001
From: Arjun Ramesh <arjunr2 at andrew.cmu.edu>
Date: Mon, 1 Sep 2025 21:31:04 -0400
Subject: [PATCH 2/4] Added tests for wasm32 wali target compilation

---
 clang/test/Driver/unsupported-target-arch.c | 10 +++++++++
 clang/test/Driver/wasm-toolchain.c          |  7 ++++++
 clang/test/Driver/wasm-toolchain.cpp        | 25 +++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/clang/test/Driver/unsupported-target-arch.c b/clang/test/Driver/unsupported-target-arch.c
index 426f646db50b0..b5874a41e7ef6 100644
--- a/clang/test/Driver/unsupported-target-arch.c
+++ b/clang/test/Driver/unsupported-target-arch.c
@@ -77,3 +77,13 @@
 // RUN: not %clang_cl --target=x86-unknown-uefi -o %t.o %s 2> %t.err
 // RUN: FileCheck --input-file=%t.err -check-prefixes=CHECK-x86 %s
 // CHECK-x86: error: unknown target triple 'x86-unknown-uefi'{{$}}
+
+// Linux API for wasm must include `wali` vendor and `linux` OS
+//
+// RUN: not %clang -### --target=wasm32-linux-musl -o %t.o %s 2> %t.err \
+// RUN: FileCheck --input-file=%t.err -check-prefixes=CHECK-WASM-WALI-NO-VENDOR %s
+// CHECK-WASM-WALI-NO-VENDOR: error: unknown target triple 'wasm32-unknown-linux-musl'
+//
+// RUN: not %clang -### --target=wasm32-wali-wasi-musl -o %t.o %s 2> %t.err \
+// RUN: FileCheck --input-file=%t.err -check-prefixes=CHECK-WASM-WALI-NO-LINUX %s
+// CHECK-WASM-WALI-NO-LINUX: error: unknown target triple 'wasm32-wali-wasi-musl'
diff --git a/clang/test/Driver/wasm-toolchain.c b/clang/test/Driver/wasm-toolchain.c
index 91803fe6bc1f2..0abf75f2b998d 100644
--- a/clang/test/Driver/wasm-toolchain.c
+++ b/clang/test/Driver/wasm-toolchain.c
@@ -296,3 +296,10 @@
 // RUN:   | FileCheck -check-prefix=LINK_WASIP2_USE_WASMLD %s
 // LINK_WASIP2_USE_WASMLD: "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_WASIP2_USE_WASMLD: wasm-ld{{.*}}" "-m" "wasm32" {{.*}} "[[temp]]" {{.*}}
+
+// Basic `wasm32-wali-linux-musl` compile-link test.
+
+// RUN: %clang -### --target=wasm32-wali-linux-musl --sysroot=/foo %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=LINK_WALI_BASIC %s
+// LINK_WALI_BASIC: "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
+// LINK_WALI_BASIC: wasm-ld{{.*}}" "-L/foo/lib/wasm32-linux-musl" "crt1.o" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins.a" "-o" "a.out"
diff --git a/clang/test/Driver/wasm-toolchain.cpp b/clang/test/Driver/wasm-toolchain.cpp
index ba1c55b33edca..3b1587033b547 100644
--- a/clang/test/Driver/wasm-toolchain.cpp
+++ b/clang/test/Driver/wasm-toolchain.cpp
@@ -86,3 +86,28 @@
 // COMPILE_STDCXX: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
 // COMPILE_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/wasm32-wasi"
 // COMPILE_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include"
+
+// RUN: %clangxx -### --target=wasm32-wali-linux-musl --stdlib=libc++ %s 2>&1 \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree/usr \
+// RUN:   | FileCheck -check-prefix=COMPILE_WALI %s
+// COMPILE_WALI: "-cc1"
+// COMPILE_WALI: "-resource-dir" "[[RESOURCE_DIR:[^"]*]]"
+// COMPILE_WALI: "-isysroot" "[[SYSROOT:[^"]+]]"
+// COMPILE_WALI: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/wasm32-linux-musl/c++/v1"
+// COMPILE_WALI: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/c++/v1"
+// COMPILE_WALI: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
+// COMPILE_WALI: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/wasm32-linux-musl"
+// COMPILE_WALI: "-internal-isystem" "[[SYSROOT:[^"]+]]/include"
+
+// RUN: %clangxx -### --target=wasm32-wali-linux-musl --stdlib=libstdc++ %s 2>&1 \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libstdcxx_libcxxv2_tree/usr \
+// RUN:   | FileCheck -check-prefix=COMPILE_WALI_STDCXX %s
+// COMPILE_WALI_STDCXX: "-cc1"
+// COMPILE_WALI_STDCXX: "-resource-dir" "[[RESOURCE_DIR:[^"]*]]"
+// COMPILE_WALI_STDCXX: "-isysroot" "[[SYSROOT:[^"]+]]"
+// COMPILE_WALI_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/c++/4.8/wasm32-linux-musl"
+// COMPILE_WALI_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/c++/4.8"
+// COMPILE_WALI_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/c++/4.8/backward"
+// COMPILE_WALI_STDCXX: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
+// COMPILE_WALI_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include/wasm32-linux-musl"
+// COMPILE_WALI_STDCXX: "-internal-isystem" "[[SYSROOT:[^"]+]]/include"

>From f5cedb2b1c7ce8082da38c688754a4dde3e2a053 Mon Sep 17 00:00:00 2001
From: Arjun Ramesh <arjunr2 at andrew.cmu.edu>
Date: Thu, 4 Sep 2025 15:15:50 -0400
Subject: [PATCH 3/4] Add link to WALI ABI and fix unwind for sjlj non-wasm
 targets

---
 clang/lib/Basic/Targets/WebAssembly.h  | 5 ++++-
 libunwind/src/UnwindRegistersRestore.S | 8 ++++++--
 libunwind/src/UnwindRegistersSave.S    | 8 ++++++--
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/clang/lib/Basic/Targets/WebAssembly.h b/clang/lib/Basic/Targets/WebAssembly.h
index 81fd40a62d3a3..4de6ce6bb5a21 100644
--- a/clang/lib/Basic/Targets/WebAssembly.h
+++ b/clang/lib/Basic/Targets/WebAssembly.h
@@ -90,7 +90,10 @@ class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
     MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
     HasUnalignedAccess = true;
     if (T.isWALI()) {
-      // WALI ABI requires 64-bit longs on both wasm32 and wasm64
+      // The WALI ABI is documented here:
+      // https://doc.rust-lang.org/rustc/platform-support/wasm32-wali-linux.html
+      // Currently, this ABI only applies to wasm32 targets and notably requires
+      // 64-bit longs
       LongAlign = LongWidth = 64;
       SizeType = UnsignedInt;
       PtrDiffType = SignedInt;
diff --git a/libunwind/src/UnwindRegistersRestore.S b/libunwind/src/UnwindRegistersRestore.S
index eda0b10205ac3..c916cca277cca 100644
--- a/libunwind/src/UnwindRegistersRestore.S
+++ b/libunwind/src/UnwindRegistersRestore.S
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__)
+#if !defined(__wasm__)
 
 #include "assembly.h"
 
@@ -22,6 +22,8 @@
   .text
 #endif
 
+#if !defined(__USING_SJLJ_EXCEPTIONS__)
+
 #if defined(__i386__)
 DEFINE_LIBUNWIND_FUNCTION(__libunwind_Registers_x86_jumpto)
 #
@@ -1250,6 +1252,8 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind19Registers_loongarch6jumptoEv)
 
 #endif
 
+#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) */
+
 NO_EXEC_STACK_DIRECTIVE
 
-#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__) */
+#endif /* !defined(__wasm__) */
diff --git a/libunwind/src/UnwindRegistersSave.S b/libunwind/src/UnwindRegistersSave.S
index a2ff6578b1057..66d8e962a16d0 100644
--- a/libunwind/src/UnwindRegistersSave.S
+++ b/libunwind/src/UnwindRegistersSave.S
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__)
+#if !defined(__wasm__)
 
 #include "assembly.h"
 
@@ -22,6 +22,8 @@
     .text
 #endif
 
+#if !defined(__USING_SJLJ_EXCEPTIONS__)
+
 #if defined(__i386__)
 
 #
@@ -1232,6 +1234,8 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
   WEAK_ALIAS(__unw_getcontext, unw_getcontext)
 #endif
 
+#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) */
+
 NO_EXEC_STACK_DIRECTIVE
 
-#endif /* !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__wasm__) */
+#endif /* !defined(__wasm__) */
\ No newline at end of file

>From a07eb13e9658f08abf1bcc4d4723b5a9438573c8 Mon Sep 17 00:00:00 2001
From: Arjun Ramesh <arjunr2 at andrew.cmu.edu>
Date: Thu, 4 Sep 2025 15:29:18 -0400
Subject: [PATCH 4/4] Add newline

---
 libunwind/src/UnwindRegistersSave.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libunwind/src/UnwindRegistersSave.S b/libunwind/src/UnwindRegistersSave.S
index 66d8e962a16d0..8bf99ebd942fa 100644
--- a/libunwind/src/UnwindRegistersSave.S
+++ b/libunwind/src/UnwindRegistersSave.S
@@ -1238,4 +1238,4 @@ DEFINE_LIBUNWIND_FUNCTION(__unw_getcontext)
 
 NO_EXEC_STACK_DIRECTIVE
 
-#endif /* !defined(__wasm__) */
\ No newline at end of file
+#endif /* !defined(__wasm__) */

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