[WebAssembly] Add TLS data segment flag: WASM_SEG_FLAG_TLS

Previously the linker was relying solely on the name of the segment
to imply TLS.

Differential Revision: https://reviews.llvm.org/D102202

include/llvm/BinaryFormat/Wasm.h

@@ -359,6 +359,7 @@ enum WasmSymbolType : unsigned {
 
 enum WasmSegmentFlag : unsigned {
   WASM_SEG_FLAG_STRINGS = 0x1,
+  WASM_SEG_FLAG_TLS = 0x2,
 };
 
 // Kinds of event attributes.

lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -2009,11 +2009,14 @@ static const Comdat *getWasmComdat(const GlobalValue *GV) {
 static unsigned getWasmSectionFlags(SectionKind K) {
   unsigned Flags = 0;
 
-  // TODO(sbc): Add suport for K.isMergeableConst()
+  if (K.isThreadLocal())
+    Flags |= wasm::WASM_SEG_FLAG_TLS;
 
   if (K.isMergeableCString())
     Flags |= wasm::WASM_SEG_FLAG_STRINGS;
 
+  // TODO(sbc): Add suport for K.isMergeableConst()
+
   return Flags;
 }
 

lib/MC/MCParser/WasmAsmParser.cpp

@@ -100,6 +100,9 @@ public:
       case 'G':
         Group = true;
         break;
+      case 'T':
+        flags |= wasm::WASM_SEG_FLAG_TLS;
+        break;
       case 'S':
         flags |= wasm::WASM_SEG_FLAG_STRINGS;
         break;

lib/MC/MCSectionWasm.cpp

@@ -69,6 +69,8 @@ void MCSectionWasm::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
     OS << 'G';
   if (SegmentFlags & wasm::WASM_SEG_FLAG_STRINGS)
     OS << 'S';
+  if (SegmentFlags & wasm::WASM_SEG_FLAG_TLS)
+    OS << 'T';
 
   OS << '"';
 

lib/ObjectYAML/WasmYAML.cpp

@@ -544,6 +544,7 @@ void ScalarBitSetTraits<WasmYAML::SegmentFlags>::bitset(
     IO &IO, WasmYAML::SegmentFlags &Value) {
 #define BCase(X) IO.bitSetCase(Value, #X, wasm::WASM_SEG_FLAG_##X)
   BCase(STRINGS);
+  BCase(TLS);
 #undef BCase
 }
 

test/CodeGen/WebAssembly/target-features-tls.ll

@@ -23,4 +23,4 @@ target triple = "wasm32-unknown-unknown"
 ; BULK-MEM-NEXT: .int8 43
 ; BULK-MEM-NEXT: .int8 11
 ; BULK-MEM-NEXT: .ascii "bulk-memory"
-; BULK-MEM-NEXT: .tbss.foo,"",@
+; BULK-MEM-NEXT: .tbss.foo,"T",@

test/CodeGen/WebAssembly/tls-general-dynamic.ll

@@ -105,7 +105,7 @@ define void @tls_base_write(i8** %output) {
 }
 
 ; CHECK: .type tls,@object
-; TLS-NEXT: .section .tbss.tls,"",@
+; TLS-NEXT: .section .tbss.tls,"T",@
 ; NO-TLS-NEXT: .section .bss.tls,"",@
 ; CHECK-NEXT: .p2align 2
 ; CHECK-NEXT: tls:

test/CodeGen/WebAssembly/tls-local-exec.ll

@@ -72,7 +72,7 @@ define i32 @tls_size() {
 }
 
 ; CHECK: .type tls,@object
-; TLS-NEXT: .section .tbss.tls,"",@
+; TLS-NEXT: .section .tbss.tls,"T",@
 ; NO-TLS-NEXT: .section .bss.tls,"",@
 ; CHECK-NEXT: .p2align 2
 ; CHECK-NEXT: tls:

test/MC/WebAssembly/tls.s

@@ -5,15 +5,26 @@
 tls_store:
   .functype tls_store (i32) -> ()
   # CHECK: global.get __tls_base
-  # CHECK-NEXT: i32.const tls@TLSREL
+  # CHECK-NEXT: i32.const tls1@TLSREL
   # CHECK-NEXT: i32.add
   # CHECK-NEXT: i32.store 0
   global.get __tls_base
-  i32.const tls@TLSREL
+  i32.const tls1@TLSREL
   i32.add
   i32.store 0
   end_function
 
+.section .tls.foo,"T",@
+# CHECK: .tls.foo,"T",@
+tls1:
+  .int32 42
+  .size tls1, 4
+
+.section custom_tls,"T",@
+# CHECK: custom_tls,"T",@
+tls2:
+  .int32 43
+  .size tls2, 4
 
 #      CHECK-OBJ:  - Type:            CODE
 # CHECK-OBJ-NEXT:    Relocations:
@@ -39,5 +50,22 @@ tls_store:
 # CHECK-OBJ-NEXT:        Flags:           [ UNDEFINED ]
 # CHECK-OBJ-NEXT:      - Index:           2
 # CHECK-OBJ-NEXT:        Kind:            DATA
-# CHECK-OBJ-NEXT:        Name:            tls
+# CHECK-OBJ-NEXT:        Name:            tls1
-# CHECK-OBJ-NEXT:        Flags:           [ UNDEFINED ]
+# CHECK-OBJ-NEXT:        Flags:           [ BINDING_LOCAL ]
+# CHECK-OBJ-NEXT:        Segment:         0
+# CHECK-OBJ-NEXT:        Size:            4
+# CHECK-OBJ-NEXT:      - Index:           3
+# CHECK-OBJ-NEXT:        Kind:            DATA
+# CHECK-OBJ-NEXT:        Name:            tls2
+# CHECK-OBJ-NEXT:        Flags:           [ BINDING_LOCAL ]
+# CHECK-OBJ-NEXT:        Segment:         1
+# CHECK-OBJ-NEXT:        Size:            4
+# CHECK-OBJ-NEXT:    SegmentInfo:
+# CHECK-OBJ-NEXT:      - Index:           0
+# CHECK-OBJ-NEXT:        Name:            .tls.foo
+# CHECK-OBJ-NEXT:        Alignment:       0
+# CHECK-OBJ-NEXT:        Flags:           [ TLS ]
+# CHECK-OBJ-NEXT:      - Index:           1
+# CHECK-OBJ-NEXT:        Name:            custom_tls
+# CHECK-OBJ-NEXT:        Alignment:       0
+# CHECK-OBJ-NEXT:        Flags:           [ TLS ]