[llvm] r321058 - [X86] Use a specific list of MVTs in combineShiftRightArithmetic instead of iterating over every integer VT and checking their size.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Mon Dec 18 22:29:00 2017
New Revision: 321058

URL: http://llvm.org/viewvc/llvm-project?rev=321058&view=rev
Log:
[X86] Use a specific list of MVTs in combineShiftRightArithmetic instead of iterating over every integer VT and checking their size.

Previously, we were checking for MVTs with sizes betwen 8 and 64 which only includes i8, i16, i32, and i64 today. But I don't think we should assume that and should list the types that are legal for x86. I also don't think we need i64 since type legalization is guaranteed to split those up.

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

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=321058&r1=321057&r2=321058&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Dec 18 22:29:00 2017
@@ -32565,11 +32565,11 @@ static SDValue combineShiftRightArithmet
   if (SarConst.isNegative())
     return SDValue();
 
-  for (MVT SVT : MVT::integer_valuetypes()) {
+  for (MVT SVT : { MVT::i8, MVT::i16, MVT::i32 }) {
     unsigned ShiftSize = SVT.getSizeInBits();
     // skipping types without corresponding sext/zext and
     // ShlConst that is not one of [56,48,32,24,16]
-    if (ShiftSize < 8 || ShiftSize > 64 || ShlConst != Size - ShiftSize)
+    if (ShiftSize >= Size || ShlConst != Size - ShiftSize)
       continue;
     SDLoc DL(N);
     SDValue NN =