From: Florian Krohm <flo2030@eich-krohm.de>
Date: Wed, 3 Sep 2025 15:07:52 +0000 (+0000)
Subject: ir_opt.c:  Algebraic simplification for Iop_Shl/Shr/Sar.
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=98d3c055b97b980a78c7d18560a11f64aeca981c;p=thirdparty%2Fvalgrind.git

ir_opt.c:  Algebraic simplification for Iop_Shl/Shr/Sar.

The simplification rules for 32-bit and 64-bit operands also apply for
8-bit and 16-bit operands.
---

diff --git a/VEX/priv/ir_opt.c b/VEX/priv/ir_opt.c
index b362be007..f38a7be64 100644
--- a/VEX/priv/ir_opt.c
+++ b/VEX/priv/ir_opt.c
@@ -2571,31 +2571,34 @@ static IRExpr* fold_Expr_WRK ( IRExpr** env, IRExpr* e )
          /* other cases (identities, etc) */
          switch (e->Iex.Binop.op) {
 
+            case Iop_Shl8:
+            case Iop_Shl16:
             case Iop_Shl32:
             case Iop_Shl64:
+            case Iop_Shr8:
+            case Iop_Shr16:
+            case Iop_Shr32:
             case Iop_Shr64:
+            case Iop_Sar8:
+            case Iop_Sar16:
+            case Iop_Sar32:
             case Iop_Sar64:
-               /* Shl32/Shl64/Shr64/Sar64(x,0) ==> x */
+               /* Shl8/Shl16/Shl32/Shl64(x,0) ==> x
+                  Shr8/Shr16/Shr32/Shr64(x,0) ==> x
+                  Sar8/Sar16/Sar32/Sar64(x,0) ==> x */
                if (isZeroU(e->Iex.Binop.arg2)) {
                   e2 = e->Iex.Binop.arg1;
                   break;
                }
-               /* Shl32/Shl64/Shr64(0,x) ==> 0 */
+               /* Shl8/Shl16/Shl32/Shl64(0,x) ==> 0
+                  Shr8/Shr16/Shr32/Shr64(0,x) ==> 0
+                  Sar8/Sar16/Sar32/Sar64(0,x) ==> 0 */
                if (isZeroU(e->Iex.Binop.arg1)) {
                   e2 = e->Iex.Binop.arg1;
                   break;
                }
                break;
 
-            case Iop_Sar32:
-            case Iop_Shr32:
-               /* Shr32/Sar32(x,0) ==> x */
-               if (isZeroU(e->Iex.Binop.arg2)) {
-                  e2 = e->Iex.Binop.arg1;
-                  break;
-               }
-               break;
-
             case Iop_Or8:
             case Iop_Or16:
             case Iop_Or32: