Bug 1288944 - Baldr: mark all calls as preserving the TLS reg (r=jolesen)

MozReview-Commit-ID: 3WcKCPGRaFv

--HG--
extra : rebase_source : 96e8382d137c1a65570d97e0ba4401c6c1dfb45c

js/src/asmjs/WasmIonCompile.cpp

@@ -971,8 +971,8 @@ class FunctionCompiler
     }
 
   private:
-    bool callPrivate(MWasmCall::Callee callee, MWasmCall::PreservesTlsReg preservesTlsReg,
-                     const CallCompileState& call, ExprType ret, MDefinition** def)
+    bool callPrivate(MWasmCall::Callee callee, const CallCompileState& call, ExprType ret,
+                     MDefinition** def)
     {
         MOZ_ASSERT(!inDeadCode());
 
@@ -984,9 +984,8 @@ class FunctionCompiler
           case MWasmCall::Callee::Builtin:  kind = CallSiteDesc::Register; break;
         }
 
-        MWasmCall* ins =
-          MWasmCall::New(alloc(), CallSiteDesc(call.lineOrBytecode_, kind), callee, call.regArgs_,
-                          ToMIRType(ret), call.spIncrement_, preservesTlsReg);
+        auto* ins = MWasmCall::New(alloc(), CallSiteDesc(call.lineOrBytecode_, kind), callee,
+                                   call.regArgs_, ToMIRType(ret), call.spIncrement_);
         if (!ins)
             return false;
 
@@ -1005,7 +1004,7 @@ class FunctionCompiler
         }
 
         auto callee = MWasmCall::Callee::internal(funcIndex);
-        return callPrivate(callee, MWasmCall::PreservesTlsReg::True, call, sig.ret(), def);
+        return callPrivate(callee, call, sig.ret(), def);
     }
 
     bool funcPtrCall(uint32_t sigIndex, uint32_t length, uint32_t globalDataOffset,
@@ -1033,8 +1032,7 @@ class FunctionCompiler
             callee = MWasmCall::Callee(ptrFun, mg_.sigs[sigIndex].id);
         }
 
-        return callPrivate(callee, MWasmCall::PreservesTlsReg::True, call,
-                           mg_.sigs[sigIndex].ret(), def);
+        return callPrivate(callee, call, mg_.sigs[sigIndex].ret(), def);
     }
 
     bool callImport(unsigned globalDataOffset, const CallCompileState& call, ExprType ret,
@@ -1048,7 +1046,7 @@ class FunctionCompiler
         MOZ_ASSERT(call.tlsStackOffset_ != UINT32_MAX);
 
         auto callee = MWasmCall::Callee::import(globalDataOffset, call.tlsStackOffset_);
-        return callPrivate(callee, MWasmCall::PreservesTlsReg::False, call, ret, def);
+        return callPrivate(callee, call, ret, def);
     }
 
     bool builtinCall(SymbolicAddress builtin, const CallCompileState& call, ValType type,
@@ -1059,8 +1057,7 @@ class FunctionCompiler
             return true;
         }
 
-        return callPrivate(MWasmCall::Callee(builtin), MWasmCall::PreservesTlsReg::False,
-                           call, ToExprType(type), def);
+        return callPrivate(MWasmCall::Callee(builtin), call, ToExprType(type), def);
     }
 
     /*********************************************** Control flow generation */

js/src/jit/MIR.cpp

@@ -5379,10 +5379,9 @@ MAsmJSUnsignedToFloat32::foldsTo(TempAllocator& alloc)
 
 MWasmCall*
 MWasmCall::New(TempAllocator& alloc, const wasm::CallSiteDesc& desc, Callee callee,
-               const Args& args, MIRType resultType, size_t spIncrement,
-               PreservesTlsReg preservesTlsReg)
+               const Args& args, MIRType resultType, size_t spIncrement)
 {
-    MWasmCall* call = new(alloc) MWasmCall(desc, callee, spIncrement, preservesTlsReg);
+    MWasmCall* call = new(alloc) MWasmCall(desc, callee, spIncrement);
     call->setResultType(resultType);
 
     if (!call->argRegs_.init(alloc, args.length()))

js/src/jit/MIR.h

@@ -13586,24 +13586,16 @@ class MWasmCall final
         }
     };
 
-    enum PreservesTlsReg {
-        False = false,
-        True = true
-    };
-
   private:
     wasm::CallSiteDesc desc_;
     Callee callee_;
     FixedList<AnyRegister> argRegs_;
     size_t spIncrement_;
-    bool preservesTlsReg_;
 
-    MWasmCall(const wasm::CallSiteDesc& desc, Callee callee, size_t spIncrement,
-               PreservesTlsReg preservesTlsReg)
-      : desc_(desc)
-      , callee_(callee)
-      , spIncrement_(spIncrement)
-      , preservesTlsReg_(bool(preservesTlsReg))
+    MWasmCall(const wasm::CallSiteDesc& desc, Callee callee, size_t spIncrement)
+      : desc_(desc),
+        callee_(callee),
+        spIncrement_(spIncrement)
     { }
 
   public:
@@ -13617,8 +13609,7 @@ class MWasmCall final
     typedef Vector<Arg, 8, SystemAllocPolicy> Args;
 
     static MWasmCall* New(TempAllocator& alloc, const wasm::CallSiteDesc& desc, Callee callee,
-                          const Args& args, MIRType resultType, size_t spIncrement,
-                          PreservesTlsReg preservesTlsReg);
+                          const Args& args, MIRType resultType, size_t spIncrement);
 
     size_t numArgs() const {
         return argRegs_.length();
@@ -13642,11 +13633,6 @@ class MWasmCall final
         return spIncrement_;
     }
 
-    // Does this call preserve the value of the TLS pointer register?
-    bool preservesTlsReg() const {
-        return preservesTlsReg_;
-    }
-
     bool possiblyCalls() const override {
         return true;
     }

js/src/jit/shared/LIR-shared.h

@@ -8294,10 +8294,11 @@ class LWasmCallBase : public LInstruction
         return true;
     }
     bool isCallPreserved(AnyRegister reg) const override {
-        // WebAssembly functions preserve the TLS pointer register.
-        if (reg.isFloat() || reg.gpr() != WasmTlsReg)
-            return false;
-        return mir()->preservesTlsReg();
+        // All MWasmCalls preserve the TLS register:
+        //  - internal/indirect calls do by the internal wasm ABI
+        //  - import calls do by explicitly saving/restoring at the callsite
+        //  - builtin calls do because the TLS reg is non-volatile
+        return !reg.isFloat() && reg.gpr() == WasmTlsReg;
     }
 
     // LInstruction interface