spirv-opt: Suppress assertion error for 16 bit integer extended instructions in CCP pass (KhronosGroup#6287)

* Suppress assertion error for 16 bit extended instructions in CCP pass

* Update comment

Co-authored-by: Steven Perron <stevenperron@google.com>

---------

Co-authored-by: Steven Perron <stevenperron@google.com>

Author: luciechoi

source/opt/ccp_pass.cpp

@@ -360,6 +360,13 @@ void CCPPass::Initialize() {
     }
   }
 
+  // Mark the extended instruction imports as `kVarying`. We know they
+  // will not be constants, and will be used by `OpExtInst` instructions.
+  // This allows those instructions to be fully processed.
+  for (const auto& inst : get_module()->ext_inst_imports()) {
+    values_[inst.result_id()] = kVaryingSSAId;
+  }
+
   original_id_bound_ = context()->module()->IdBound();
 }
 

test/opt/ccp_test.cpp

@@ -1237,6 +1237,34 @@ TEST_F(CCPTest, CCPNoChangeFailureWithUnfoldableInstr) {
   EXPECT_EQ(std::get<1>(result), Pass::Status::SuccessWithChange);
 }
 
+TEST_F(CCPTest, CCPSuccessWithNoCCPOnExtendedInstruction) {
+  // We don't expect to have Constant Propagation on certain
+  // extended instructions with 16 bit integers. This is to
+  // test that this stage doesn't throw errors. If we add support
+  // for 16 bit integers, this test should change.
+
+  const std::string text = R"(OpCapability Shader
+OpCapability Float16
+%1 = OpExtInstImport "GLSL.std.450"
+OpMemoryModel Logical GLSL450
+OpEntryPoint Fragment %main "main"
+OpExecutionMode %main OriginUpperLeft
+OpSource GLSL 140
+OpName %main "main"
+%void = OpTypeVoid
+%half = OpTypeFloat 16
+%half_0x1p_0 = OpConstant %half 0x1p+0
+%6 = OpTypeFunction %void
+%main = OpFunction %void None %6
+%7 = OpLabel
+%8 = OpExtInst %half %1 Cos %half_0x1p_0
+OpReturn
+OpFunctionEnd
+)";
+
+  SinglePassRunAndCheck<CCPPass>(text, text, false);
+}
+
 TEST_F(CCPTest, FunctionDeclaration) {
   // Make sure the pass works with a function declaration that is called.
   const std::string text = R"(OpCapability Addresses