[PATCH] D38065: [instCombine] Handle (X & C2) < C1 --> (X & C2) == 0

[Phabricator via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL313819: [InstCombine] Handle (X & C2) < C1 --> (X & C2) == 0 (authored by ctopper).

Changed prior to commit:
  https://reviews.llvm.org/D38065?vs=115937&id=116071#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D38065

Files:
  llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/trunk/test/Transforms/InstCombine/icmp.ll


Index: llvm/trunk/test/Transforms/InstCombine/icmp.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp.ll
+++ llvm/trunk/test/Transforms/InstCombine/icmp.ll
@@ -1141,7 +1141,7 @@
 define i1 @test67inverse(i32 %x) {
 ; CHECK-LABEL: @test67inverse(
 ; CHECK-NEXT:    [[AND:%.*]] = and i32 [[X:%.*]], 96
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[AND]], 32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[AND]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %and = and i32 %x, 127
@@ -1178,7 +1178,7 @@
 define <2 x i1> @test67vecinverse(<2 x i32> %x) {
 ; CHECK-LABEL: @test67vecinverse(
 ; CHECK-NEXT:    [[AND:%.*]] = and <2 x i32> [[X:%.*]], <i32 96, i32 96>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult <2 x i32> [[AND]], <i32 32, i32 32>
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i32> [[AND]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %and = and <2 x i32> %x, <i32 96, i32 96>
Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1715,12 +1715,19 @@
   }
 
   // (X & C2) > C1 --> (X & C2) != 0, if any bit set in (X & C2) will produce a
-  // result greater than C1.
-  unsigned NumTZ = C2->countTrailingZeros();
-  if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && NumTZ < C2->getBitWidth() &&
-      NumTZ >= C1->getActiveBits()) {
-    Constant *Zero = Constant::getNullValue(And->getType());
-    return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
+ // result greater than C1. Also handle (X & C2) < C1 --> (X & C2) == 0.
+  if (!C2->isNullValue()) {
+    unsigned NumTZ = C2->countTrailingZeros();
+    if (Cmp.getPredicate() == ICmpInst::ICMP_UGT &&
+        NumTZ >= C1->getActiveBits()) {
+      Constant *Zero = Constant::getNullValue(And->getType());
+      return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
+    }
+    if (Cmp.getPredicate() == ICmpInst::ICMP_ULT &&
+        NumTZ >= C1->ceilLogBase2()) {
+      Constant *Zero = Constant::getNullValue(And->getType());
+      return new ICmpInst(ICmpInst::ICMP_EQ, And, Zero);
+    }
   }
 
   return nullptr;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D38065.116071.patch
Type: text/x-patch
Size: 2279 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170920/03f617c1/attachment.bin>