[GISel] Explicitly disable BF16 tablegen patterns.

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -296,8 +296,21 @@ void IRTranslator::addMachineCFGPred(CFGEdge Edge, MachineBasicBlock *NewPred) {
   MachinePreds[Edge].push_back(NewPred);
 }
 
+static bool containsBF16Type(const User &U) {
+  // BF16 cannot currently be represented by LLT, to avoid miscompiles we
+  // prevent any instructions using them. FIXME: This can be removed once LLT
+  // supports bfloat.
+  return U.getType()->getScalarType()->isBFloatTy() ||
+         any_of(U.operands(), [](Value *V) {
+           return V->getType()->getScalarType()->isBFloatTy();
+         });
+}
+
 bool IRTranslator::translateBinaryOp(unsigned Opcode, const User &U,
                                      MachineIRBuilder &MIRBuilder) {
+  if (containsBF16Type(U))
+    return false;
+
   // Get or create a virtual register for each value.
   // Unless the value is a Constant => loadimm cst?
   // or inline constant each time?
@@ -317,6 +330,9 @@ bool IRTranslator::translateBinaryOp(unsigned Opcode, const User &U,
 
 bool IRTranslator::translateUnaryOp(unsigned Opcode, const User &U,
                                     MachineIRBuilder &MIRBuilder) {
+  if (containsBF16Type(U))
+    return false;
+
   Register Op0 = getOrCreateVReg(*U.getOperand(0));
   Register Res = getOrCreateVReg(U);
   uint32_t Flags = 0;
@@ -334,6 +350,9 @@ bool IRTranslator::translateFNeg(const User &U, MachineIRBuilder &MIRBuilder) {
 
 bool IRTranslator::translateCompare(const User &U,
                                     MachineIRBuilder &MIRBuilder) {
+  if (containsBF16Type(U))
+    return false;
+
   auto *CI = cast<CmpInst>(&U);
   Register Op0 = getOrCreateVReg(*U.getOperand(0));
   Register Op1 = getOrCreateVReg(*U.getOperand(1));
@@ -1553,8 +1572,7 @@ bool IRTranslator::translateBitCast(const User &U,
 
 bool IRTranslator::translateCast(unsigned Opcode, const User &U,
                                  MachineIRBuilder &MIRBuilder) {
-  if (U.getType()->getScalarType()->isBFloatTy() ||
-      U.getOperand(0)->getType()->getScalarType()->isBFloatTy())
+  if (containsBF16Type(U))
     return false;
 
   uint32_t Flags = 0;
@@ -2647,6 +2665,8 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
 
 bool IRTranslator::translateInlineAsm(const CallBase &CB,
                                       MachineIRBuilder &MIRBuilder) {
+  if (containsBF16Type(CB))
+    return false;
 
   const InlineAsmLowering *ALI = MF->getSubtarget().getInlineAsmLowering();
 
@@ -2736,6 +2756,9 @@ bool IRTranslator::translateCallBase(const CallBase &CB,
 }
 
 bool IRTranslator::translateCall(const User &U, MachineIRBuilder &MIRBuilder) {
+  if (containsBF16Type(U))
+    return false;
+
   const CallInst &CI = cast<CallInst>(U);
   auto TII = MF->getTarget().getIntrinsicInfo();
   const Function *F = CI.getCalledFunction();
@@ -3371,6 +3394,9 @@ bool IRTranslator::translateAtomicCmpXchg(const User &U,
 
 bool IRTranslator::translateAtomicRMW(const User &U,
                                       MachineIRBuilder &MIRBuilder) {
+  if (containsBF16Type(U))
+    return false;
+
   const AtomicRMWInst &I = cast<AtomicRMWInst>(U);
   auto Flags = TLI->getAtomicMemOperandFlags(I, *DL);
 

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -1017,7 +1017,7 @@ bool TargetPassConfig::addCoreISelPasses() {
   if (Selector != SelectorType::GlobalISel || !isGlobalISelAbortEnabled())
     DebugifyIsSafe = false;
 
-  // Add instruction selector passes.
+  // Add instruction selector passes for global isel if enabled.
   if (Selector == SelectorType::GlobalISel) {
     SaveAndRestore SavedAddingMachinePasses(AddingMachinePasses, true);
     if (addIRTranslator())
@@ -1043,15 +1043,14 @@ bool TargetPassConfig::addCoreISelPasses() {
     // Pass to reset the MachineFunction if the ISel failed.
     addPass(createResetMachineFunctionPass(
         reportDiagnosticWhenGlobalISelFallback(), isGlobalISelAbortEnabled()));
+  }
 
-    // Provide a fallback path when we do not want to abort on
-    // not-yet-supported input.
-    if (!isGlobalISelAbortEnabled() && addInstSelector())
+  // Run the SDAG InstSelector, providing a fallback path when we do not want to
+  // abort on not-yet-supported input.
+  if (Selector != SelectorType::GlobalISel || !isGlobalISelAbortEnabled())
+    if (addInstSelector())
       return true;
 
-  } else if (addInstSelector())
-    return true;
-
   // Expand pseudo-instructions emitted by ISel. Don't run the verifier before
   // FinalizeISel.
   addPass(&FinalizeISelID);