Improve removal of dead calls to allocator helpers.

This change improves detection of allocators with side effects.
Allocators can cause side effects if the allocated object may have a finalizer.
This change adds a pHasSideEffects parameter to getNewHelper JitEE interface
method. It's used by the jit to check for allocator side effects instead of
guessing from helper ids.

Fixes #21530.

1 files changed, 8 insertions, 9 deletions

diff --git a/src/jit/compiler.hpp b/src/jit/compiler.hpp
index 29a79f862b..3fceff729a 100644
--- a/src/jit/compiler.hpp
+++ b/src/jit/compiler.hpp
@@ -1157,21 +1157,20 @@ inline GenTreeCall* Compiler::gtNewHelperCallNode(unsigned helper, var_types typ
 // gtNewAllocObjNode: A little helper to create an object allocation node.
 //
 // Arguments:
-//    helper           - Value returned by ICorJitInfo::getNewHelper
-//    clsHnd           - Corresponding class handle
-//    type             - Tree return type (e.g. TYP_REF)
-//    op1              - Node containing an address of VtablePtr
+//    helper               - Value returned by ICorJitInfo::getNewHelper
+//    helperHasSideEffects - True iff allocation helper has side effects
+//    clsHnd               - Corresponding class handle
+//    type                 - Tree return type (e.g. TYP_REF)
+//    op1                  - Node containing an address of VtablePtr
 //
 // Return Value:
 //    Returns GT_ALLOCOBJ node that will be later morphed into an
 //    allocation helper call or local variable allocation on the stack.
 
-inline GenTreeAllocObj* Compiler::gtNewAllocObjNode(unsigned int         helper,
-                                                    CORINFO_CLASS_HANDLE clsHnd,
-                                                    var_types            type,
-                                                    GenTree*             op1)
+inline GenTreeAllocObj* Compiler::gtNewAllocObjNode(
+    unsigned int helper, bool helperHasSideEffects, CORINFO_CLASS_HANDLE clsHnd, var_types type, GenTree* op1)
 {
-    GenTreeAllocObj* node = new (this, GT_ALLOCOBJ) GenTreeAllocObj(type, helper, clsHnd, op1);
+    GenTreeAllocObj* node = new (this, GT_ALLOCOBJ) GenTreeAllocObj(type, helper, helperHasSideEffects, clsHnd, op1);
     return node;
 }