llvm-reduce: Fix operand reduction asserting on target ext types (llvm#132732)

Not all TargetExtTypes support zeroinit, so use poison as a substitute
if unavailable.

Author: arsenm

llvm/test/tools/llvm-reduce/reduce-operands-target-ext-ty.ll

@@ -0,0 +1,26 @@
+; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-zero --test FileCheck --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck --check-prefixes=CHECK,ZERO %s < %t
+
+; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=operands-one --test FileCheck --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck --check-prefixes=CHECK,ONE %s < %t
+
+declare void @uses_ext_ty(target("sometarget.sometype"))
+
+; TODO: Should support reduce to poison
+; CHECK-LABEL: @foo(
+; ZERO: call void @uses_ext_ty(target("sometarget.sometype") %arg)
+; ONE: call void @uses_ext_ty(target("sometarget.sometype") %arg)
+define void @foo(target("sometarget.sometype") %arg) {
+  call void @uses_ext_ty(target("sometarget.sometype") %arg)
+  ret void
+}
+
+declare void @uses_zeroinit_ext_ty(target("sometarget.sometype"))
+
+; CHECK-LABEL: @bar(
+; ZERO: call void @uses_zeroinit_ext_ty(target("spirv.sometype") zeroinitializer)
+; ONE: call void @uses_zeroinit_ext_ty(target("spirv.sometype") %arg)
+define void @bar(target("spirv.sometype") %arg) {
+  call void @uses_zeroinit_ext_ty(target("spirv.sometype") %arg)
+  ret void
+}

llvm/tools/llvm-reduce/deltas/ReduceOperands.cpp

@@ -134,6 +134,17 @@ void llvm::reduceOperandsZeroDeltaPass(TestRunner &Test) {
     if (auto *IntTy = dyn_cast<IntegerType>(Op->getType()))
       if (switchCaseExists(Op, ConstantInt::get(IntTy, 0)))
         return nullptr;
+
+    if (auto *TET = dyn_cast<TargetExtType>(Op->getType())) {
+      if (isa<ConstantTargetNone, PoisonValue>(Op))
+        return nullptr;
+      if (TET->hasProperty(TargetExtType::HasZeroInit))
+        return ConstantTargetNone::get(TET);
+
+      // TODO: Poison reduction for this case
+      return nullptr;
+    }
+
     // Don't replace existing zeroes.
     return isZero(Op) ? nullptr : Constant::getNullValue(Op->getType());
   };