support multiple phis and undef

Author: alexbaden

test/LLVMIR/freeze-masked-div-rem.ll

@@ -15,7 +15,7 @@ if.end:
   ; CHECK: [[F0:%.*]] = freeze i8 %yy
   ; CHECK-NEXT: %z = sdiv i8 %x, [[F0:%.*]]
   %z = sdiv i8 %x, %yy
-  br i1 %cmp, label %if2.then, label %if2.end 
+  br i1 %cmp, label %if2.then, label %if2.end
 
 if2.then:
   store i8 %z, ptr %v, align 8
@@ -46,12 +46,12 @@ if.end:
   ; CHECK: [[F1:%.*]] = freeze i8 %bb
   ; CHECK-NEXT: %zz = sdiv i8 %x, [[F1:%.*]]
   %zz = sdiv i8 %x, %bb
-  br i1 %cmp, label %if2.then, label %if2.end 
+  br i1 %cmp, label %if2.then, label %if2.end
 
 if2.then:
   store i8 %z, ptr %v, align 8
   br label %if2.end
 
 if2.end:
   ret void
-}
+}

third_party/intel/lib/LLVMIR/LLVMIRFreezeMaskedDivRem.cpp

@@ -6,10 +6,10 @@
 
 using namespace llvm;
 
-static bool processBasicBlock(BasicBlock &BB, PHINode *PhiNode) {
+static bool processPhiNode(BasicBlock &BB, PHINode *PhiNode) {
   if (!any_of(PhiNode->incoming_values(), [](Use &U) {
         Constant *C = dyn_cast<Constant>(&U);
-        return C && C->isNullValue();
+        return isa<UndefValue>(U) || C && C->isNullValue();
       })) {
     return false;
   }
@@ -34,12 +34,8 @@ static bool runOnFunction(Function &F) {
   bool Changed = false;
 
   for (BasicBlock &BB : F) {
-    for (Instruction &I : BB) {
-      if (PHINode *PhiNode = dyn_cast<PHINode>(&I)) {
-        Changed |= processBasicBlock(BB, PhiNode);
-        continue;
-      }
-      break;
+    for (PHINode &PhiNode : BB.phis()) {
+      Changed |= processPhiNode(BB, &PhiNode);
     }
   }