[llvm] 37f422f - [WebAssembly] Use GeneralDynamic TLS for exception handling builtins.

[Sam Clegg via llvm-commits]

Author: Sam Clegg
Date: 2022-02-14T14:08:32-08:00
New Revision: 37f422f4ac31c8b8041c6b62065263314282dab6

URL: https://github.com/llvm/llvm-project/commit/37f422f4ac31c8b8041c6b62065263314282dab6
DIFF: https://github.com/llvm/llvm-project/commit/37f422f4ac31c8b8041c6b62065263314282dab6.diff

LOG: [WebAssembly] Use GeneralDynamic TLS for exception handling builtins.

These global TLS symbols are shared across all shared libraries and
therefor should not be assumed to be local to the current module.

Also add new error in the linker when TLS relocations are used against
undefined symbols.  TLS relocations are offsets into the current modules
tls data segment, and don't make sense for undefined symbols which are
modeled as global imports.

Fixes: https://github.com/emscripten-core/emscripten/issues/13398

Differential Revision: https://reviews.llvm.org/D119630

Added: 
    

Modified: 
    lld/test/wasm/relocation-bad-tls.s
    lld/wasm/Relocations.cpp
    llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
    llvm/test/CodeGen/WebAssembly/lower-em-exceptions.ll
    llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll

Removed: 
    


################################################################################
diff  --git a/lld/test/wasm/relocation-bad-tls.s b/lld/test/wasm/relocation-bad-tls.s
index 99197244a6217..63522ebd8c979 100644
--- a/lld/test/wasm/relocation-bad-tls.s
+++ b/lld/test/wasm/relocation-bad-tls.s
@@ -6,6 +6,8 @@ _start:
   .functype _start () -> ()
   i32.const foo at TLSREL
   i32.const bar at TLSREL
+  i32.const baz at TLSREL
+  drop
   drop
   drop
   end_function
@@ -24,3 +26,4 @@ bar:
 
 # CHECK: relocation R_WASM_MEMORY_ADDR_TLS_SLEB cannot be used against `foo` in non-TLS section: .data
 # CHECK: relocation R_WASM_MEMORY_ADDR_TLS_SLEB cannot be used against `bar` in non-TLS section: .bss
+# CHECK: relocation R_WASM_MEMORY_ADDR_TLS_SLEB cannot be used against an undefined symbol `baz`

diff  --git a/lld/wasm/Relocations.cpp b/lld/wasm/Relocations.cpp
index b0acd66465aeb..0109b6743f5c6 100644
--- a/lld/wasm/Relocations.cpp
+++ b/lld/wasm/Relocations.cpp
@@ -112,6 +112,11 @@ void scanRelocations(InputChunk *chunk) {
       break;
     case R_WASM_MEMORY_ADDR_TLS_SLEB:
     case R_WASM_MEMORY_ADDR_TLS_SLEB64:
+      if (!sym->isDefined()) {
+        error(toString(file) + ": relocation " + relocTypeToString(reloc.Type) +
+              " cannot be used against an undefined symbol `" + toString(*sym) +
+              "`");
+      }
       // In single-threaded builds TLS is lowered away and TLS data can be
       // merged with normal data and allowing TLS relocation in non-TLS
       // segments.

diff  --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
index b6c43be03aba0..38415507b23ca 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -422,7 +422,7 @@ static GlobalVariable *getGlobalVariable(Module &M, Type *Ty,
   // shared-memory module, which we don't want to be responsible for.
   auto *Subtarget = TM.getSubtargetImpl();
   auto TLS = Subtarget->hasAtomics() && Subtarget->hasBulkMemory()
-                 ? GlobalValue::LocalExecTLSModel
+                 ? GlobalValue::GeneralDynamicTLSModel
                  : GlobalValue::NotThreadLocal;
   GV->setThreadLocalMode(TLS);
   return GV;

diff  --git a/llvm/test/CodeGen/WebAssembly/lower-em-exceptions.ll b/llvm/test/CodeGen/WebAssembly/lower-em-exceptions.ll
index 4624285d70b37..95d7c9f2fb535 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-em-exceptions.ll
+++ b/llvm/test/CodeGen/WebAssembly/lower-em-exceptions.ll
@@ -9,8 +9,8 @@ target triple = "wasm32-unknown-unknown"
 @_ZTIc = external constant i8*
 ; NO-TLS-DAG: __THREW__ = external global [[PTR]]
 ; NO-TLS-DAG: __threwValue = external global i32
-; TLS-DAG: __THREW__ = external thread_local(localexec) global [[PTR]]
-; TLS-DAG: __threwValue = external thread_local(localexec) global i32
+; TLS-DAG: __THREW__ = external thread_local global [[PTR]]
+; TLS-DAG: __threwValue = external thread_local global i32
 
 ; Test invoke instruction with clauses (try-catch block)
 define void @clause() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {

diff  --git a/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll b/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
index 57612f687afdf..a153c20aae2fa 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
+++ b/llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll
@@ -10,8 +10,8 @@ target triple = "wasm32-unknown-unknown"
 @global_var = global i32 0, align 4
 ; NO-TLS-DAG: __THREW__ = external global [[PTR]]
 ; NO-TLS-DAG: __threwValue = external global [[PTR]]
-; TLS-DAG: __THREW__ = external thread_local(localexec) global i32
-; TLS-DAG: __threwValue = external thread_local(localexec) global i32
+; TLS-DAG: __THREW__ = external thread_local global i32
+; TLS-DAG: __threwValue = external thread_local global i32
 @global_longjmp_ptr = global void (%struct.__jmp_buf_tag*, i32)* @longjmp, align 4
 ; CHECK-DAG: @global_longjmp_ptr = global void (%struct.__jmp_buf_tag*, i32)* bitcast (void ([[PTR]], i32)* @emscripten_longjmp to void (%struct.__jmp_buf_tag*, i32)*)