[OpaquePointers] Correctly find leader of EC in type scavenger (#2133)

Signed-off-by: Lu, John <john.lu@intel.com>

Author: LU-JOHN

lib/SPIRV/SPIRVTypeScavenger.cpp

@@ -252,7 +252,7 @@ Type *SPIRVTypeScavenger::substituteTypeVariables(Type *T) {
   }
   if (auto Index = isTypeVariable(T)) {
     unsigned TypeVarNum = *Index;
-    TypeVarNum = UnifiedTypeVars.join(TypeVarNum, TypeVarNum);
+    TypeVarNum = UnifiedTypeVars.findLeader(TypeVarNum);
     Type *&SubstTy = TypeVariables[TypeVarNum];
     // A value in TypeVariables may itself contain type variables that need to
     // be substituted. Substitute these as well.
@@ -273,9 +273,7 @@ bool SPIRVTypeScavenger::unifyType(Type *T1, Type *T2) {
     return true;
 
   auto SetTypeVar = [&](unsigned TypeVarNum, Type *ActualTy) {
-    // .findLeader doesn't work in uncompressed mode, so use .join with itself
-    // to find the leader.
-    unsigned Leader = UnifiedTypeVars.join(TypeVarNum, TypeVarNum);
+    unsigned Leader = UnifiedTypeVars.findLeader(TypeVarNum);
 
     // This method might be called with T1 as a concrete type containing
     // pointers, and we want to make sure those don't leak into type variables.
@@ -411,7 +409,7 @@ void SPIRVTypeScavenger::typeModule(Module &M) {
   // them as an i8* type.
   Type *Int8Ty = Type::getInt8Ty(M.getContext());
   for (const auto &[TypeVarNum, TypeVar] : enumerate(TypeVariables)) {
-    unsigned PrimaryVar = UnifiedTypeVars.join(TypeVarNum, TypeVarNum);
+    unsigned PrimaryVar = UnifiedTypeVars.findLeader(TypeVarNum);
     Type *LeaderTy = TypeVariables[PrimaryVar];
     if (TypeVar)
       TypeVar = substituteTypeVariables(TypeVar);

test/type-scavenger/equivalence.ll

@@ -0,0 +1,79 @@
+; Test if llvm-spirv type scavenging has an assertion 
+; failure due to incorrect lookup of an equivalence class leader.
+
+; RUN: llvm-as < %s | llvm-spirv -o %t.spv
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv %t.spv -o - -to-text | FileCheck %s --check-prefix=CHECK-SPIRV
+; RUN: llvm-spirv %t.spv -o - -r | llvm-dis | FileCheck %s --check-prefix=CHECK-LLVM
+
+; Incorrect lookup of equivalence class leader caused an assertion failure when
+; processing call instruction to this name
+; CHECK-SPIRV: _func0
+; CHECK-LLVM: _func0
+
+target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
+target triple = "spir64-unknown-unknown"
+
+define spir_func void @_func1() {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %call3 = call spir_func ptr addrspace(4) @_func2()
+  %call5 = call spir_func ptr addrspace(4) @_func0(ptr addrspace(4) %call3, i64 0)
+  br label %for.cond
+}
+
+define spir_func void @_func3() {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %call3 = call spir_func ptr @_func4()
+  %call3.ascast = addrspacecast ptr %call3 to ptr addrspace(4)
+  %call5 = call spir_func ptr addrspace(4) @_func0(ptr addrspace(4) %call3.ascast, i64 0)
+  br label %for.cond
+}
+
+declare spir_func ptr addrspace(4) @_func5()
+
+define spir_func void @_func6(ptr addrspace(4) %call3.ascast) {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %call5 = call spir_func ptr addrspace(4) @_func0(ptr addrspace(4) %call3.ascast, i64 0)
+  br label %for.cond
+}
+
+define spir_func void @_func7() {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %call3 = call spir_func ptr addrspace(4) @_func5()
+  %call5 = call spir_func ptr addrspace(4) @_func0(ptr addrspace(4) %call3, i64 0)
+  br label %for.cond
+}
+
+declare spir_func ptr @_func4()
+
+declare spir_func ptr addrspace(4) @_func2()
+
+define spir_func ptr addrspace(4) @_func0(ptr addrspace(4) %this, i64 %index) {
+entry:
+  %arrayidx = getelementptr [5 x i32], ptr addrspace(4) %this, i64 0, i64 %index
+  ret ptr addrspace(4) null
+}
+
+define spir_func void @_func8() {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %call8 = call spir_func ptr addrspace(4) @_func0(ptr addrspace(4) null, i64 0)
+  br label %for.cond
+}
+
+; uselistorder directives
+uselistorder ptr @_func0, { 0, 4, 3, 2, 1 }