//
// If the remainder of the struct local is dying, then we expect that this
// entire struct local is now dying, since all field accesses are going to be
-// replaced with other locals. The exception is if there is a queued read
-// back for any of the fields.
+// replaced with other locals.
+//
+// There are two exceptions to the above:
+//
+// 1) If there is a queued readback for any of the fields, then there is
+// live state in the struct local, so it is not dying.
+//
+// 2) If there are further uses of the local in the same statement then we cannot
+// actually act on the last-use information we would provide here. That's because
+// uses of locals occur at the user and we do not model that here. In the real model
+// there are cases where we do not have any place to insert any IR between the two uses.
+// For example, consider:
+//
+// ▌ CALL void Program:Foo(Program+S,Program+S)
+// ├──▌ LCL_VAR struct<Program+S, 4> V01 loc0
+// └──▌ LCL_VAR struct<Program+S, 4> V01 loc0
+//
+// If V01 is promoted fully then both uses of V01 are last uses here; but
+// replacing the IR with
+//
+// ▌ CALL void Program:Foo(Program+S,Program+S)
+// ├──▌ LCL_VAR struct<Program+S, 4> V01 loc0 (last use)
+// └──▌ COMMA struct
+// ├──▌ STORE_LCL_FLD int V01 loc0 [+0]
+// │ └──▌ LCL_VAR int V02 tmp0
+// └──▌ LCL_VAR struct<Program+S, 4> V01 loc0 (last use)
+//
+// would be illegal since the created store overlaps with the first local,
+// and does not take into account that both uses occur simultaneously at
+// the position of the CALL node.
//
bool ReplaceVisitor::IsPromotedStructLocalDying(GenTreeLclVarCommon* lcl)
{
}
}
+ for (GenTree* cur = lcl->gtNext; cur != nullptr; cur = cur->gtNext)
+ {
+ assert(cur->OperIsAnyLocal());
+ if (cur->TypeIs(TYP_STRUCT) && (cur->AsLclVarCommon()->GetLclNum() == lcl->GetLclNum()))
+ {
+ return false;
+ }
+ }
+
return true;
}
GenTree* readBack = Promotion::CreateWriteBack(m_compiler, lcl, rep);
Statement* stmt = m_compiler->fgNewStmtFromTree(readBack);
- JITDUMP("Writing back %s before " FMT_STMT "\n", rep.Description, stmt->GetID());
+ JITDUMP("Writing back %s before " FMT_STMT "\n", rep.Description, m_currentStmt->GetID());
DISPSTMT(stmt);
m_compiler->fgInsertStmtBefore(m_currentBlock, m_currentStmt, stmt);
ClearNeedsWriteBack(rep);
--- /dev/null
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Xunit;
+using System.Runtime.CompilerServices;
+
+public class Runtime_91056
+{
+ [Fact]
+ public static void TestEntryPoint()
+ {
+ S s = default;
+ if (False())
+ {
+ s.A = 1234;
+ }
+
+ Foo(0, 0, s, s);
+ }
+
+ [MethodImpl(MethodImplOptions.NoInlining)]
+ private static bool False() => false;
+
+ [MethodImpl(MethodImplOptions.NoInlining)]
+ private static void Foo(int a, int b, S s1, S s2)
+ {
+ }
+
+ public struct S
+ {
+ public int A;
+ }
+}
\ No newline at end of file
projects / platform / upstream / dotnet / runtime.git / commitdiff