Fix SPIRV `OpSpecConstantOp` emit (#7158)

* Fix SPIRV specialization constant with floating-point operations

* Improve test

* WIP

* Restrict `OpSpecConstantOp` allowed operations based on SPIRV specifications

* Fix typo on floating type check

* Emit error on float to int spec cosnt int val casts

2 files changed, 99 insertions, 0 deletions

diff --git a/tests/spirv/spec-constant-int-val-float-to-int-cast.slang b/tests/spirv/spec-constant-int-val-float-to-int-cast.slang
new file mode 100644
index 000000000..9f9f96178
--- /dev/null
+++ b/tests/spirv/spec-constant-int-val-float-to-int-cast.slang
@@ -0,0 +1,15 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK): -entry computeMain -stage compute -target spirv
+
+// CHECK: error 38041: cannot cast non-integer specialization
+// CHECK-NEXT: const float X
+
+[[SpecializationConstant]]
+const float X = 10.0;
+
+[shader("compute")]
+[numthreads(32, 1, 1)]
+void computeMain() : SV_Target
+{
+    float arr[int(X)];
+    float a = arr[0];
+}
diff --git a/tests/spirv/spec-constant-operations.slang b/tests/spirv/spec-constant-operations.slang
new file mode 100644
index 000000000..86d16ef34
--- /dev/null
+++ b/tests/spirv/spec-constant-operations.slang
@@ -0,0 +1,84 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv
+//TEST(compute, vulkan):COMPARE_COMPUTE(filecheck-buffer=BUF):-vk -output-using-type -emit-spirv-directly
+
+//TEST_INPUT:ubuffer(data=[0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+// `OpSpecConstantOp` can only contain integer operations when targeting Vulkan SPIRV, not floating-point operations.
+// This test checks that floating-point operations that strictly contain specialization constant variables are not declared with `OpSpecContantOp`,
+// while integer operations that strictly contain specializaton constant operands are declared as `OpSpecConstantOp`.
+
+// CHECK-DAG: OpSpecConstant %float 1
+// CHECK-DAG: OpSpecConstant %ulong 256
+// CHECK-DAG: OpSpecConstant %float 100
+// CHECK-DAG: OpSpecConstantOp %half FConvert
+// CHECK-DAG: OpSpecConstantOp %int UConvert
+
+// CHECK-NOT: OpSpecConstantOp {{.*}} FAdd
+// CHECK-NOT: OpSpecConstantOp {{.*}} FSub
+// CHECK-NOT: OpSpecConstantOp {{.*}} FMul
+// CHECK-NOT: OpSpecConstantOp {{.*}} FDiv
+// CHECK-NOT: OpSpecConstantOp {{.*}} SpvOpConvertUToF
+// CHECK-NOT: OpSpecConstantOp {{.*}} SpvOpConvertFToU
+
+[[SpecializationConstant]]
+const float X = 1.0;
+[[SpecializationConstant]]
+const uint64_t Y = 256;
+[[SpecializationConstant]]
+const float Z = 100.0;
+
+int func1()
+{
+    // Test float-to-float and int-to-int conversions.
+    int a = int(Y);
+    half b = half(X);
+    int16_t c = int16_t(Y);
+
+    // Test comparisons.
+    if (X < 2.0)
+    {
+        a = 3;
+    }
+    else if (X > 5.0)
+    {
+        a = 5;
+    }
+
+    if (Y < 200)
+    {
+        b = 2.0h;
+    }
+    else if (Y > 500)
+    {
+        b = 5.0h;
+    }
+
+    return a + int(b) + int(c);
+}
+
+float func2()
+{
+    // Test floating-point arithmetic.
+    float a = X + Z;
+    a += (X - Z);
+    a += (X * Z);
+    a += (X / Z);
+
+    return a;
+}
+
+float func3()
+{
+    // Test float-to-int and int-to-float conversions.
+    int a = int(Z) * 2;
+    return float(Y) + float(a);
+}
+
+[shader("compute")]
+[numthreads(1, 1, 1)]
+void computeMain()
+{
+    // BUF: 818.01
+    outputBuffer[0] = float(func1()) + func2() + func3();
+}