Allow select nodes to constant propagate

src/coreclr/jit/assertionprop.cpp

@@ -5834,7 +5834,8 @@ GenTree* Compiler::optVNConstantPropOnJTrue(BasicBlock* block, GenTree* test)
 Compiler::fgWalkResult Compiler::optVNConstantPropCurStmt(BasicBlock* block, Statement* stmt, GenTree* tree)
 {
     // Don't perform const prop on expressions marked with GTF_DONT_CSE
-    if (!tree->CanCSE())
+
+    if (!tree->CanCSE() && !(tree->gtFlags & GTF_DO_CONST_PROP))
     {
         return WALK_CONTINUE;
     }
@@ -5870,6 +5871,13 @@ Compiler::fgWalkResult Compiler::optVNConstantPropCurStmt(BasicBlock* block, Sta
         case GT_NEG:
         case GT_CAST:
         case GT_INTRINSIC:
+        case GT_SELECT:
+        case GT_CEQ:
+        case GT_CNE:
+        case GT_CLT:
+        case GT_CLE:
+        case GT_CGE:
+        case GT_CGT:
             break;
 
         case GT_JTRUE:

src/coreclr/jit/gentree.h

@@ -426,6 +426,8 @@ enum GenTreeFlags : unsigned int
     GTF_UNSIGNED    = 0x00008000, // With GT_CAST:   the source operand is an unsigned type
                                   // With operators: the specified node is an unsigned operator
     GTF_SPILL       = 0x00020000, // Needs to be spilled here
+    GTF_DO_CONST_PROP = 0x00040000, // Always constant propegate, regardless of GTF_DONT_CSE
+                                    // Ideally replace with GTF_DONT_CONST_PROP
 
 // The extra flag GTF_IS_IN_CSE is used to tell the consumer of the side effect flags
 // that we are calling in the context of performing a CSE, thus we
@@ -436,7 +438,7 @@ enum GenTreeFlags : unsigned int
 
     GTF_IS_IN_CSE   = GTF_BOOLEAN,
 
-    GTF_COMMON_MASK = 0x0003FFFF, // mask of all the flags above
+    GTF_COMMON_MASK = 0x0005FFFF, // mask of all the flags above
 
     GTF_REUSE_REG_VAL = 0x00800000, // This is set by the register allocator on nodes whose value already exists in the
                                     // register assigned to this node, so the code generator does not have to generate

src/coreclr/jit/optimizer.cpp

@@ -4639,7 +4639,8 @@ bool Compiler::optIfConvertSelect(GenTree* original_condition, GenTree* asg_node
 
     // Duplicate the condition and invert it
     GenTree* cond = gtCloneExpr(original_condition);
-    cond->gtFlags |= (GTF_RELOP_JMP_USED | GTF_DONT_CSE);
+    cond->gtFlags |= (GTF_DONT_CSE | GTF_DO_CONST_PROP);
+    cond->gtFlags ^= GTF_RELOP_JMP_USED;
     cond->gtFlags ^= GTF_RELOP_NAN_UN;
     switch (cond->gtOper)
     {