From a80d1c1615eeed8e82d9a9c5474bfdbf34e346da Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Wed, 21 Aug 2024 13:08:27 -0700
Subject: [PATCH] [release/9.0] Fix Issue #105820 (#106656)

* Check for writing sign flag for skipping test condition in compare to zero

* Only skip test instruction in case Writes_PF, Writes ZF, WritesSF, ResetsCF and ResetsOF are true

---------

Co-authored-by: Khushal Modi <kcmodi@asu.edu>
Co-authored-by: Jeff Schwartz <jeffschw@microsoft.com>
---
 src/coreclr/jit/emitxarch.cpp | 19 ++++++++++++++++++-
 src/coreclr/jit/emitxarch.h   |  1 +
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/coreclr/jit/emitxarch.cpp b/src/coreclr/jit/emitxarch.cpp
index e3561bbff3797..2b98d14183aba 100644
--- a/src/coreclr/jit/emitxarch.cpp
+++ b/src/coreclr/jit/emitxarch.cpp
@@ -355,6 +355,22 @@ bool emitter::DoesWriteZeroFlag(instruction ins)
     return (flags & Writes_ZF) != 0;
 }
 
+//------------------------------------------------------------------------
+// DoesWriteParityFlag: check if the instruction write the
+//     PF flag.
+//
+// Arguments:
+//    ins - instruction to test
+//
+// Return Value:
+//    true if instruction writes the PF flag, false otherwise.
+//
+bool emitter::DoesWriteParityFlag(instruction ins)
+{
+    insFlags flags = CodeGenInterface::instInfo[ins];
+    return (flags & Writes_PF) != 0;
+}
+
 //------------------------------------------------------------------------
 // DoesWriteSignFlag: check if the instruction writes the
 //     SF flag.
@@ -979,7 +995,8 @@ bool emitter::AreFlagsSetToZeroCmp(regNumber reg, emitAttr opSize, GenCondition
     // Certain instruction like and, or and xor modifies exactly same flags
     // as "test" instruction.
     // They reset OF and CF to 0 and modifies SF, ZF and PF.
-    if (DoesResetOverflowAndCarryFlags(lastIns))
+    if (DoesResetOverflowAndCarryFlags(lastIns) && DoesWriteSignFlag(lastIns) && DoesWriteZeroFlag(lastIns) &&
+        DoesWriteParityFlag(lastIns))
     {
         return id->idOpSize() == opSize;
     }
diff --git a/src/coreclr/jit/emitxarch.h b/src/coreclr/jit/emitxarch.h
index d24a697d93c72..7ff6902613d59 100644
--- a/src/coreclr/jit/emitxarch.h
+++ b/src/coreclr/jit/emitxarch.h
@@ -484,6 +484,7 @@ bool        IsThreeOperandAVXInstruction(instruction ins) const;
 static bool HasRegularWideForm(instruction ins);
 static bool HasRegularWideImmediateForm(instruction ins);
 static bool DoesWriteZeroFlag(instruction ins);
+static bool DoesWriteParityFlag(instruction ins);
 static bool DoesWriteSignFlag(instruction ins);
 static bool DoesResetOverflowAndCarryFlags(instruction ins);
 bool        IsFlagsAlwaysModified(instrDesc* id);