From cba5d6bed85a43f15f10092552431c3000820392 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Fri, 18 Sep 2020 23:37:50 -0700
Subject: [PATCH] [X86] Return from SimplifyDemandedBitsForTargetNode after
 calculating known bits for VSHLI/VSRAI/VSRLI.

We were breaking out of the switch which falls into the default
implementation of SimplifyDemandedBitsForTargetNode which is a
wrapper around computeKnownBits. So we end up doing the recursion
and known bits calculation all over again. Instead we should return
with the known bits we calculated in the switch.
---
 lib/Target/X86/X86ISelLowering.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 2070517f1e8..9ff0f511e07 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -38084,7 +38084,7 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
 
     // Low bits known zero.
     Known.Zero.setLowBits(ShAmt);
-    break;
+    return false;
   }
   case X86ISD::VSRLI: {
     unsigned ShAmt = Op.getConstantOperandVal(1);
@@ -38103,7 +38103,7 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
 
     // High bits known zero.
     Known.Zero.setHighBits(ShAmt);
-    break;
+    return false;
   }
   case X86ISD::VSRAI: {
     SDValue Op0 = Op.getOperand(0);
@@ -38152,7 +38152,7 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
     // High bits are known one.
     if (Known.One[BitWidth - ShAmt - 1])
       Known.One.setHighBits(ShAmt);
-    break;
+    return false;
   }
   case X86ISD::PEXTRB:
   case X86ISD::PEXTRW: {