SPIR-V type for i8 always aliases the type for i32

This is incrementally better than what we have now, but I suspect
we should have remapped the types earlier in the flow, and we should
never see the i8 at this point.

Fixes google#15

lib/SPIRVProducerPass.cpp

@@ -1642,8 +1642,27 @@ void SPIRVProducerPass::GenerateSPIRVTypes(const DataLayout &DL) {
         SPIRVInstList.push_back(Inst);
       } else {
         // i8 is added to TypeMap as i32.
+        // No matter what LLVM type is requested first, always alias the
+        // second one's SPIR-V type to be the same as the one we generated
+        // first.
+        int aliasToWidth = 0;
         if (BitWidth == 8) {
+          aliasToWidth = 32;
           BitWidth = 32;
+        } else if (BitWidth == 32) {
+          aliasToWidth = 8;
+        }
+        if (aliasToWidth) {
+          Type* otherType = Type::getIntNTy(Ty->getContext(), aliasToWidth);
+          auto where = TypeMap.find(otherType);
+          if (where == TypeMap.end()) {
+            // Go ahead and make it, but also map the other type to it.
+            TypeMap[otherType] = nextID;
+          } else {
+            // Alias this SPIR-V type the existing type.
+            TypeMap[Ty] = where->second;
+            break;
+          }
         }
 
         SPIRVOperand *Ops[2] = {

test/char4_issue15_a.cl

@@ -0,0 +1,21 @@
+// Test for https://github.com/google/clspv/issues/15
+// Use of <4 x 18> was generating a duplicate of OpTypeInt 32 0.
+
+// In this example, the uint is mentioned before the char4.
+kernel void dup(global uint* A, global char4 *B) {}
+
+// RUN: clspv %s -S -o %t.spvasm
+// RUN: FileCheck %s < %t.spvasm
+// RUN: clspv %s -o %t.spv
+// RUN: spirv-dis -o %t2.spvasm %t.spv
+// RUN: FileCheck %s < %t2.spvasm
+// RUN: spirv-val --target-env vulkan1.0 %t.spv
+
+
+// CHECK: [[uint:%[_a-zA-Z0-9]+]] = OpTypeInt 32 0
+// CHECK-NOT: OpTypeInt 32 0
+
+// Ensure both buffer types use the same underlying i32
+// CHECK-DAG: OpTypeRuntimeArray [[uint]]
+// CHECK-DAG: OpTypeRuntimeArray [[uint]]
+

test/char4_issue15_b.cl

@@ -0,0 +1,21 @@
+// Test for https://github.com/google/clspv/issues/15
+// Use of <4 x 18> was generating a duplicate of OpTypeInt 32 0.
+
+// In this example, the char4 is mentioned before the uint.
+kernel void dup(global char4* A, global uint *B) {}
+
+// RUN: clspv %s -S -o %t.spvasm
+// RUN: FileCheck %s < %t.spvasm
+// RUN: clspv %s -o %t.spv
+// RUN: spirv-dis -o %t2.spvasm %t.spv
+// RUN: FileCheck %s < %t2.spvasm
+// RUN: spirv-val --target-env vulkan1.0 %t.spv
+
+
+// CHECK: [[uint:%[_a-zA-Z0-9]+]] = OpTypeInt 32 0
+// CHECK-NOT: OpTypeInt 32 0
+
+// Ensure both buffer types use the same underlying i32
+// CHECK-DAG: OpTypeRuntimeArray [[uint]]
+// CHECK-DAG: OpTypeRuntimeArray [[uint]]
+