[WebAssembly] Strip TLS when "atomics" is not enabled

With f3b4f99, the exclusive source of
truth for whether threads are supported is the -matomics flag.
Accordingly, strip TLS flags when -matomic is not specified, even if
bulk-memory is specified and it would theoretically be supportable.
This allows the backend to compile TLS variables when -mbulk-memory is
enabled but threads are not enabled.

Differential Revision: https://reviews.llvm.org/D125730

Author: sunfishcode

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -203,11 +203,12 @@ class CoalesceFeaturesAndStripAtomics final : public ModulePass {
     bool StrippedAtomics = false;
     bool StrippedTLS = false;
 
-    if (!Features[WebAssembly::FeatureAtomics])
+    if (!Features[WebAssembly::FeatureAtomics]) {
       StrippedAtomics = stripAtomics(M);
-
-    if (!Features[WebAssembly::FeatureBulkMemory])
       StrippedTLS = stripThreadLocals(M);
+    } else if (!Features[WebAssembly::FeatureBulkMemory]) {
+      StrippedTLS |= stripThreadLocals(M);
+    }
 
     if (StrippedAtomics && !StrippedTLS)
       stripThreadLocals(M);

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

@@ -1,5 +1,5 @@
-; RUN: llc < %s -mattr=-bulk-memory | FileCheck %s --check-prefixes NO-BULK-MEM
-; RUN: llc < %s -mattr=+bulk-memory | FileCheck %s --check-prefixes BULK-MEM
+; RUN: llc < %s -mattr=-bulk-memory,atomics | FileCheck %s --check-prefixes NO-BULK-MEM
+; RUN: llc < %s -mattr=+bulk-memory,atomics | FileCheck %s --check-prefixes BULK-MEM
 
 ; Test that the target features section contains -atomics or +atomics
 ; for modules that have thread local storage in their source.
@@ -10,15 +10,21 @@ target triple = "wasm32-unknown-unknown"
 
 ; -bulk-memory
 ; NO-BULK-MEM-LABEL: .custom_section.target_features,"",@
-; NO-BULK-MEM-NEXT: .int8 1
+; NO-BULK-MEM-NEXT: .int8 2
+; NO-BULK-MEM-NEXT: .int8 43
+; NO-BULK-MEM-NEXT: .int8 7
+; NO-BULK-MEM-NEXT: .ascii "atomics"
 ; NO-BULK-MEM-NEXT: .int8 45
 ; NO-BULK-MEM-NEXT: .int8 10
 ; NO-BULK-MEM-NEXT: .ascii "shared-mem"
 ; NO-BULK-MEM-NEXT: .bss.foo,"",@
 
 ; +bulk-memory
 ; BULK-MEM-LABEL: .custom_section.target_features,"",@
-; BULK-MEM-NEXT: .int8 1
+; BULK-MEM-NEXT: .int8 2
+; BULK-MEM-NEXT: .int8 43
+; BULK-MEM-NEXT: .int8 7
+; BULK-MEM-NEXT: .ascii "atomics"
 ; BULK-MEM-NEXT: .int8 43
 ; BULK-MEM-NEXT: .int8 11
 ; BULK-MEM-NEXT: .ascii "bulk-memory"

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

@@ -1,8 +1,8 @@
-; RUN: not --crash llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory 2>&1 | FileCheck %s --check-prefix=ERROR
-; RUN: not --crash llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory -fast-isel 2>&1 | FileCheck %s --check-prefix=ERROR
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory --mtriple wasm32-unknown-emscripten | FileCheck %s --check-prefixes=CHECK,TLS
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory --mtriple wasm32-unknown-emscripten -fast-isel | FileCheck %s --check-prefixes=CHECK,TLS
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=-bulk-memory | FileCheck %s --check-prefixes=CHECK,NO-TLS
+; RUN: not --crash llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory,atomics 2>&1 | FileCheck %s --check-prefix=ERROR
+; RUN: not --crash llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory,atomics -fast-isel 2>&1 | FileCheck %s --check-prefix=ERROR
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory,atomics --mtriple wasm32-unknown-emscripten | FileCheck %s --check-prefixes=CHECK,TLS
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory,atomics --mtriple wasm32-unknown-emscripten -fast-isel | FileCheck %s --check-prefixes=CHECK,TLS
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=-bulk-memory,atomics | FileCheck %s --check-prefixes=CHECK,NO-TLS
 target triple = "wasm32-unknown-unknown"
 
 ; ERROR: LLVM ERROR: only -ftls-model=local-exec is supported for now on non-Emscripten OSes: variable tls

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

@@ -1,6 +1,6 @@
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory | FileCheck %s --check-prefixes=CHECK,TLS
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory -fast-isel | FileCheck %s --check-prefixes=CHECK,TLS
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=-bulk-memory | FileCheck %s --check-prefixes=CHECK,NO-TLS
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory,atomics | FileCheck %s --check-prefixes=CHECK,TLS
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=+bulk-memory,atomics -fast-isel | FileCheck %s --check-prefixes=CHECK,TLS
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -mattr=-bulk-memory,atomics | FileCheck %s --check-prefixes=CHECK,NO-TLS
 target triple = "wasm32-unknown-unknown"
 
 ; CHECK-LABEL: address_of_tls: