[SPIRV] Fix failing assertion in SPIRVAsmPrinter (#166909)

With `+SPV_KHR_float_controls2` and when there is a non-int
`OpConstantNull` we
would call `MI.getOperand(1).getImm()` when `MI` was not an `OpTypeInt`
(the
associated test has an `OpTypeArray` zeroinitialized).
Under this conditions an assertion is triggered.

This patch adds the missing condition.

Author: jmmartinez

llvm/lib/Target/SPIRV/SPIRVAsmPrinter.cpp

@@ -612,13 +612,10 @@ void SPIRVAsmPrinter::outputExecutionMode(const Module &M) {
         // Collect the SPIRVTypes for fp16, fp32, and fp64 and the constant of
         // type int32 with 0 value to represent the FP Fast Math Mode.
         std::vector<const MachineInstr *> SPIRVFloatTypes;
-        const MachineInstr *ConstZero = nullptr;
+        const MachineInstr *ConstZeroInt32 = nullptr;
         for (const MachineInstr *MI :
              MAI->getMSInstrs(SPIRV::MB_TypeConstVars)) {
-          // Skip if the instruction is not OpTypeFloat or OpConstant.
           unsigned OpCode = MI->getOpcode();
-          if (OpCode != SPIRV::OpTypeFloat && OpCode != SPIRV::OpConstantNull)
-            continue;
 
           // Collect the SPIRV type if it's a float.
           if (OpCode == SPIRV::OpTypeFloat) {
@@ -629,14 +626,18 @@ void SPIRVAsmPrinter::outputExecutionMode(const Module &M) {
               continue;
             }
             SPIRVFloatTypes.push_back(MI);
-          } else {
+            continue;
+          }
+
+          if (OpCode == SPIRV::OpConstantNull) {
             // Check if the constant is int32, if not skip it.
             const MachineRegisterInfo &MRI = MI->getMF()->getRegInfo();
             MachineInstr *TypeMI = MRI.getVRegDef(MI->getOperand(1).getReg());
-            if (!TypeMI || TypeMI->getOperand(1).getImm() != 32)
-              continue;
-
-            ConstZero = MI;
+            bool IsInt32Ty = TypeMI &&
+                             TypeMI->getOpcode() == SPIRV::OpTypeInt &&
+                             TypeMI->getOperand(1).getImm() == 32;
+            if (IsInt32Ty)
+              ConstZeroInt32 = MI;
           }
         }
 
@@ -657,9 +658,9 @@ void SPIRVAsmPrinter::outputExecutionMode(const Module &M) {
           MCRegister TypeReg =
               MAI->getRegisterAlias(MF, MI->getOperand(0).getReg());
           Inst.addOperand(MCOperand::createReg(TypeReg));
-          assert(ConstZero && "There should be a constant zero.");
+          assert(ConstZeroInt32 && "There should be a constant zero.");
           MCRegister ConstReg = MAI->getRegisterAlias(
-              ConstZero->getMF(), ConstZero->getOperand(0).getReg());
+              ConstZeroInt32->getMF(), ConstZeroInt32->getOperand(0).getReg());
           Inst.addOperand(MCOperand::createReg(ConstReg));
           outputMCInst(Inst);
         }

llvm/test/CodeGen/SPIRV/non_int_constant_null.ll

@@ -0,0 +1,25 @@
+; RUN: llc -mtriple spirv64-unknown-unknown %s --spirv-ext=+SPV_KHR_float_controls2 -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -mtriple spirv64-unknown-unknown %s --spirv-ext=+SPV_KHR_float_controls2 -o - -filetype=obj | spirv-val %}
+
+@A = addrspace(1) constant [1 x i8] zeroinitializer
+
+; CHECK: OpName %[[#FOO:]] "foo"
+; CHECK: OpName %[[#A:]] "A"
+; CHECK: OpDecorate %[[#A]] Constant
+; CHECK: OpDecorate %[[#A]] LinkageAttributes "A" Export
+; CHECK: %[[#INT8:]] = OpTypeInt 8 0
+; CHECK: %[[#INT32:]] = OpTypeInt 32 0
+; CHECK: %[[#ONE:]] = OpConstant %[[#INT32]] 1
+; CHECK: %[[#ARR_INT8:]] = OpTypeArray %[[#INT8]] %7
+; CHECK: %[[#ARR_INT8_PTR:]] = OpTypePointer CrossWorkgroup %[[#ARR_INT8]]
+; CHECK: %[[#ARR_INT8_ZERO:]] = OpConstantNull %[[#ARR_INT8]]
+; CHECK: %13 = OpVariable %[[#ARR_INT8_PTR]] CrossWorkgroup %[[#ARR_INT8_ZERO]]
+; CHECK: %[[#FOO]] = OpFunction
+; CHECK: = OpLabel
+; CHECK: OpReturn
+; CHECK: OpFunctionEnd
+
+define spir_kernel void @foo() {
+entry:
+  ret void
+}