[PATCH] D129103: [InstCombine] [NFC] use C.isNegatedPowerOf2() instead of (~C + 1).isPowerOf2()

[Chenbing.Zheng via Phabricator via llvm-commits]

Chenbing.Zheng created this revision.
Chenbing.Zheng added reviewers: spatel, RKSimon, benshi001.
Chenbing.Zheng added a project: LLVM.
Herald added a subscriber: hiraditya.
Herald added a project: All.
Chenbing.Zheng requested review of this revision.
Herald added subscribers: llvm-commits, jacquesguan.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D129103

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll


Index: llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll
===================================================================
--- llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll
+++ llvm/test/Transforms/InstCombine/lshr-and-negC-icmpeq-zero.ll
@@ -234,3 +234,18 @@
   %r = icmp eq i32 %and, 1  ; should be comparing with 0
   ret i1 %r
 }
+
+; Not NegatedPowerOf2
+
+define i1 @scalar_i8_lshr_and_negC_eq_not_negatedPowerOf2(i8 %x, i8 %y) {
+; CHECK-LABEL: @scalar_i8_lshr_and_negC_eq_not_negatedPowerOf2(
+; CHECK-NEXT:    [[TMP1:%.*]] = shl i8 -3, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = and i8 [[TMP1]], [[X:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp eq i8 [[TMP2]], 0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %lshr = lshr i8 %x, %y
+  %and = and i8 %lshr, 253  ; -3
+  %r = icmp eq i8 %and, 0
+  ret i1 %r
+}
Index: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1779,7 +1779,7 @@
 
     // Restrict this fold only for single-use 'and' (PR10267).
     // ((%x & C) == 0) --> %x u< (-C)  iff (-C) is power of two.
-    if ((~(*C2) + 1).isPowerOf2()) {
+    if (C2->isNegatedPowerOf2()) {
       Constant *NegBOC =
           ConstantExpr::getNeg(cast<Constant>(And->getOperand(1)));
       auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;


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