reduce branchless because branchless has more instructions

microsoft · Dec 26, 2024 · 1e4e256 · 1e4e256
1 parent 63e80f8
commit 1e4e256
Show file tree

Hide file tree

Showing 2 changed files with 8 additions and 5 deletions.
diff --git a/libs/server/Storage/Functions/MainStore/RMWMethods.cs b/libs/server/Storage/Functions/MainStore/RMWMethods.cs
@@ -83,13 +83,14 @@ public bool InitialUpdater(ref SpanByte key, ref RawStringInput input, ref SpanB
                 case RespCommand.SET:
                 case RespCommand.SETEXNX:
                     bool withEtag = input.header.CheckWithEtagFlag();
-                    int spaceForEtag = input.header.CheckWithEtagFlagMultiplier * Constants.EtagSize;
-
+                    int spaceForEtag = 0;
                     if (withEtag)
                     {
+                        spaceForEtag = Constants.EtagSize;
                         recordInfo.SetHasETag();
                     }
 
+
                     // Copy input to value
                     var newInputValue = input.parseState.GetArgSliceByRef(0).ReadOnlySpan;
                     var metadataSize = input.arg1 == 0 ? 0 : sizeof(long);

diff --git a/libs/server/Storage/Functions/MainStore/VarLenInputMethods.cs b/libs/server/Storage/Functions/MainStore/VarLenInputMethods.cs
@@ -144,10 +144,12 @@ public int GetRMWModifiedValueLength(ref SpanByte t, ref RawStringInput input, b
             if (input.header.cmd != RespCommand.NONE)
             {
                 var cmd = input.header.cmd;
-                // Branchless OR condition on A && B can be expressed as => 1-(1−A)⋅(1−B)
-                int withEtagOrHasEtag = 1 - (1 - input.header.CheckWithEtagFlagMultiplier) * (1 - Unsafe.As<bool, byte>(ref hasEtag));
 
-                int etagOffset = withEtagOrHasEtag * Constants.EtagSize;
+                int etagOffset = 0;
+                if (hasEtag || input.header.CheckWithEtagFlag())
+                {
+                    etagOffset = Constants.EtagSize;
+                }
 
                 switch (cmd)
                 {