[llvm] 721d57f - [X86] Return from SimplifyDemandedBitsForTargetNode after calculating known bits for VSHLI/VSRAI/VSRLI.

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2020-09-18T23:57:01-07:00
New Revision: 721d57f952ba0dbe02908fc897374dd6324668b9

URL: https://github.com/llvm/llvm-project/commit/721d57f952ba0dbe02908fc897374dd6324668b9
DIFF: https://github.com/llvm/llvm-project/commit/721d57f952ba0dbe02908fc897374dd6324668b9.diff

LOG: [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.

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 2070517f1e85..9ff0f511e07e 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/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: {